HIGHEST AND BEST USE OF URBAN LAND:
ENHANCING ECOSYSTEM SERVICES THROUGH LANDSCAPE TREATMENTS
WAVERLY DE BRUIJN KLAW
B.A., Syracuse University, 2005
A thesis submitted to the
Faculty of the Graduate School of the
University of Colorado in partial fulfillment
of the requirements for the degree of
Master of Urban and Regional Planning
Urban and Regional Planning Program
WAVERLY DE BRUIJN KLAW
ALL RIGHTS RESERVED
This thesis for the Master of Urban and Regional Planning degree by
Waverly de Bruijn Klaw
has been approved for the
Urban and Regional Planning Program
Austin Troy, Chair
Date: April 29, 2016
Klaw, Waverly de Bruijn (MURP, Urban and Regional Planning Program)
Highest and Best Use of Urban Land: Enhancing Ecosystem Services Through Landscape
Thesis directed by Associate Professor Austin Troy
Climate change and population growth is impacting the health of the worlds
ecosystems. This has resulted in a reduction in the ability of ecosystems to provide the
services that humans rely on, including producing food, providing clean water and air,
and moderating climate. A tenet of urban planning is determining the "highest and best
use of real estate to achieve the greatest economic value. This concept can be expanded
to address ecological value if properties also select landscape treatments that promote
resilient and regenerative ecological outcomes.
This paper investigates the impacts that landscape treatments such as grass,
trees, flowering and non-flowering vegetation, mulch, and impervious surfaces have on
the provision of ecosystem services at the community, regional, and global level. Best
practices from communities in the United States that effectively provide regulations or
incentive programs that promote ecosystem services through the application of
landscape treatments are described. This paper concludes by summarizing ecosystem
service-friendly landscape treatment recommendations that can be incorporated into
regulations or programs to promote multifunctional and regenerative landscapes.
The form and content of this abstract are approved. I recommend its publication.
Approved: Austin Troy
To my husband Bruce and our beautiful new baby Isabella.
TABLE OF CONTENTS
I. INTRODUCTION AND STATEMENT OF RESEARCH OBJECTIVES....................1
II. RESEARCH DESIGN AND METHODS.........................................6
III. THEORETICAL FRAMEWORKS: FOLLOWING NATURES PATH....................7
Design with Nature...................................................7
IV. HISTORY OF COMMUNITY LANDSCAPE TREATMENTS.........................11
V. ECOSYSTEM SERVICES.................................................13
Regulating Erosion and Soil Health..............................20
Social Relations and Cultural Identity..........................24
Regional Ecosystem Services.........................................27
Regulating Water Quality........................................30
Regulating Wildfire Hazards.....................................33
Regulating Air Quality.
Regulating Pollinators and Wildlife...............................37
Global Ecosystem Services.............................................41
VI. REGULATORY AND INCENTIVE BEST PRACTICES................................44
Codes and Ordinances..................................................44
Wildlife and Pollinators..............................................54
Erosion and Soil Health...............................................55
Comprehensive Land Use Code Update....................................56
VII. RESULTS: HOLISTIC GUIDELINES FOR ECOSYSTEM SERVICE LANDSCAPE
Water Retention and Detention Features
Impervious and Partially Pervious Areas...............................63
Fruit and Vegetable-Bearing Plants....................................64
Pesticide and Fertilizer Use..........................................65
Preserving Existing Vegetation........................................65
Benefits and Drawbacks of Landscape Treatment by Ecosystem Service....66
LIST OF FIGURES
Figure 1: IPBES Framework on the relationship between nature and human well-
LIST OF TABLES
Table 1: Ecosystem Services Described by the Millennium Ecosystem Assessment.21
Table 2: Ranking of Landscape Treatment by Ecosystem Service.................70
INTRODUCTION AND STATEMENT OF RESEARCH OBJECTIVES
In real estate transactions, the term "highest and best use is used to appraise a
property based on "the reasonable, probable and legal use of vacant land or an
improved property, which is physically possible, appropriately supported, financially
feasible, and that results in the highest value (Duncan and Brown 2009). This "value is
based on the monetary value of the existing improvements and potential uses that a
property could command in a particular real estate market, and is used for purposes of
regulating bank lending.1 However, the opportunity exists to view the value of such
property in alternate ways, such as the social or ecological value of land, both currently
and as future potential. Whether or not the social and economic value of land can be
calculated monetarily does not influence the level of benefit that can be derived, or the
level of importance of the service being provided. Therefore, this paper seeks to
address the question "how can the land itself, rather than its physical improvements, be
put to its highest and best use for society and for the environment?
Desire to determine the highest and best use for land for social and ecological
purposes emerges during a time when natural ecosystems and the human functions
they support are becoming increasingly impaired. Climate change is resulting in
changes to the urban environment, including warmer temperatures and greater
extremes in temperature and precipitation (Hunter 2011). This paper uses ecosystems,
1 The Financial Institutions Reform, Recovery, and Enforcement Act of 1989 put
measures in place to ensure uniform appraisal standards for real estate, based upon the
concept of "highest and best use.
defined as elements in nature (plants, animals, microorganisms, water, air, etc.) the
interactions between them, and the services they provide to humans (drinking water,
clean air, healthy food, and protection against natural hazards) as the framework
through which ecological and social "highest and best uses for land are evaluated
(TEEB The Economics of Ecosystems and Biodiversity 2011,1). The Millennium
Ecosystem Assessment (2005) highlighted four main findings that reveal grave realities
regarding the global status of ecosystems:
From 1955-2005, humans have changed ecosystems more rapidly and
extensively than in any comparable period of time in human history, resulting in
a "substantial and largely irreversible loss in the diversity of life on Earth.
Man-made use of ecosystems has contributed greatly to human well-being and
economic development, but these gains have been achieved at growing costs in
the form of the degradation of many ecosystem services. These problems will
"substantially diminish the benefits that future generations obtain from
The degradation of ecosystem services could grow significantly worse during the
next 50 years.
The challenge of reversing the degradation of ecosystems while meeting
increasing demands for their services involve the need for significant changes in
policies, institutions, and practices. (Millennium Ecosystem Assessment 2005,1).
It is this call for conserving and enhancing ecosystems, even through small actions in
urban environments, that this paper intends to address.
While major strides can be made by preserving large swaths of forestland or
areas with great biodiversity, strengthening the direct link between the procurement
and consumption of ecosystem benefits can help alleviate the strain on the system as a
whole, for several reasons. First, procuring and consuming products in close proximity
reduced transportation costs and associated pollution, as in the case of food production
and the pollinator species that support it. Second, employing practices that address
stormwater runoff at the source reduces costs and infrastructure associated with
processing it further away from its point of origin. Third, the benefits of some services
such as the regulation of microclimate can only be felt locally, and therefore must be
generated locally. Finally, producing ecosystem services on land that would otherwise
not serve such a "high use is efficient in that it makes the greatest use of even small
areas of land in urban settings. While land in urban areas is typically more fragmented
and degraded than larger swaths of land less influenced by humans, "at any given
density, and with appropriate consideration to the proportion and configuration of
green space and tree cover, there is substantial scope for maximising ecological
performance (Tratalos, et al. 2007, 314).
The primary area of inquiry for this paper is land within a human settlement, or
community, whose use is regulated by a governmental body. As granted by the United
States Constitution, states possess police powers to protect the health, safety, morals,
and general welfare of the people (Encyclopaedia Britannica n.d.). In many states, such
as the State of Colorado, the power to regulate land use has been further delegated to
local governments. Colorado passed the Local Government Land Use Control Enabling
Act of 1974 to assign "broad authority to local governments to plan for and regulate the
use of land within their respective jurisdictions (State of Colorado 1974, 2). Local
governments are defined as "a county, home rule or statutory city, town, territorial
charter city, or city and county (State of Colorado 1974, 2). Small towns, large cities,
and suburbs can all be examined for their ecosystem possibilities in order to
recommend improvements to regulations (land use ordinances and codes) and
What can be gained by re-envisioning land in urban and rural communities? An
investment in the design and maintenance of gardens and managed green space could
result in numerous benefits (Hunter 2011). Landscape treatments can address a
number of ecosystem services directly, such as promoting insect and small animal
habitat, reducing air and water pollution, absorbing and sequestering carbon,
regulating microclimates, and supporting soil health. Land and its level of ground
perviousness also impacts levels of stormwater runoff and infiltration, a growing
challenge in urban areas. Landscaped areas can also support recreational activities,
food production, play a role in cultural norms and social cohesion, and offer amenities
that reduce crime and increase property values. Finally, maintenance of landscape
plantings accounts for the majority (70%) of overall residential water use (McCammon
et al., 2009; St. Hilaire et al., 2008; as cited in Hayden et al., 2015), presenting an
opportunity for impactful reduction in water use. Water conservation is particularly
critical for communities in arid regions, and for those experiencing (or prone to)
This paper aims to address the following research questions:
1. What are the most promising landscape treatments that support ecosystem
services within human settlements in the United States?
2. How can landscape treatments that support ecosystem services be incorporated
into U.S. regulatory and incentive-based programs?
RESEARCH DESIGN AND METHODS
This paper aims to identify the multiple, integrated, and regenerative ways in
which landscape treatments can promote or restore ecosystem services. In order to
achieve this, research was conducted to review and analyze existing literature
comprised of scientific research, frameworks, and theoretical approaches in journal
articles and published books; meta-analysis aggregated by international organizations;
and practical reference publications. Information and data derived from this research
forms the literature review of this thesis.
Through best practices derived from the literature, a holistic set of guidelines for
landscape treatments that enhance ecosystem services has been developed that is
intended to contribute new knowledge to the field regarding integrated approaches to
landscaping that restore and enhance ecosystem services.
THEORETICAL FRAMEWORKS: FOLLOWING NATURE'S PATH
"If one accepts the simple proposition that nature is the arena of life and that a
modicum of knowledge of her processes is indispensable for survival and rather more for
existence, health and delight, it is amazing how many apparently difficult problems
present ready solutions" (McHarg 1969, 7).
When looking at ways to enhance the human benefits that ecosystem services
provide, three theoretical frameworks of design can be considered as guiding
principles: designing with nature, striving for regenerative results, and incorporating
multifunctionality to the greatest degree possible.
Design with Nature
Urban infrastructure practices of the past 100 years have relied heavily on
engineered "hard infrastructure solutions in order to enable development to occur in
locations where humans have preferred to settle (Rouse and Bunster-Ossa 2013). An
example includes piping water long distances, sometimes hundreds of miles, to serve
cities, towns, and developments. Another is conveying stormwater away from the
location upon which rain fell, necessitating expensive and energy intensive treatment
requirements in order to reduce water quality degradation in the rivers and streams
into which this water eventually drains.
In 1969, Ian McHarg made a powerful proclamation that the residential
developments sprouting up in urban and suburban areas should be designed with
consideration of natural systems. To "design with nature, he argued, one must broaden
the then-dominant concept that a purely economic cost-benefit analysis would suffice in
the siting and construction of infrastructure. McHarg made the case for identifying,
measuring, and ranking social and natural processes as social values. Natural
characteristics and processes to be valued included slope, surface drainage, soil
drainage, bedrock foundation, soil foundation, susceptibility to erosion, land value,
historic value, scenic value, recreational value, residential value, tidal inundation, water
value, forest value, wildlife value and institutional value (McHarg 1969). By looking at
overlays of these characteristics and processes, one can determine lands most valuable
for preserving and lands most suitable for development. In many ways, the social and
natural processes identified by McHarg are precursors to the identification of
ecosystem services and the definition of multifunctional landscapes as such (Yang, Li
and Li 2013).
The concept of designing systems by working with natural processes has
continued with the development of green infrastructure. Green infrastructure "mimics
natural systems to "manage stormwater runoff in a way that maintains or restores the
sites natural hydrology (U.S. Environmental Protection Agency 2010). At the site level,
green infrastructure can "absorb stormwater back into the ground (infiltration), using
trees and other natural vegetation to convert it to water vapor (evapotranspiration)
and using rain barrels or cisterns to capture and reuse stormwater (U.S.
Environmental Protection Agency 2010). Promoting ecosystem services at the site level
is the subject of this paper, which expands the concepts put forth by green
infrastructure to other ecosystem services.
In addition to working with nature, projects and designs can also seek to develop
positive, regenerative outcomes (e.g. create health and wellbeing, or restore the
capacity of ecosystems to function) rather than operating as a linear system of
resource-intensive inputs and environmentally degrading outputs (Zari 2015). One
term for this is regenerative design. At the municipal level, land use policies, procedures,
and programs can identify opportunities in the built environment to turn linear systems
that generate waste or pollution into positive feedback loops, thereby not only negating
negative effects but also contributing positively to the environmental, social, and
economic wellbeing of the structure as a whole. This can be seen in the development of
composting programs that not only reduce waste but also generate nutrients that will
enrich soil, and urban tree canopies that not only improve the aesthetic quality of urban
life but also reduce the heat island effect and improve air quality. When applied to
landscaping in urban areas, Zari argues the pre-development ecosystem should be
examined and mimicked to the greatest extent possible, while ensuring that
improvements to ecological performance dont negatively impact other ecosystem
services (Zari 2015).
"Simply put, design should let nature perform the maximum amount of work"
(Yang, Li and Li 2013, 5436).
The third theoretical concept used to develop robust and appropriate landscape
options is that of multifunctionality. According to OFarrell and Anderson, "[sjustainable
multifunctional landscapes are landscapes created and managed to integrate human
production and landscape use into the ecological fabric of a landscape maintaining
critical ecosystem function, service flows and biodiversity retention (O'Farrell and
Anderson 2010, 59). Multifunctional landscapes were prevalent in the past, where
Europe cultivated landscapes using traditional cultural practices that supported a
"range of economic, social and environmental services and also fostered a "diversity of
characteristic plants, animals and habitats (Jones-Walters 2008,117).
With global challenges such as climate change and ecosystem degradation, a
sense of urgency surrounds many decisions regarding how cities are designed, built,
and managed. Viewing plots of land for the multiple benefits that can be derived from
them such as food, a source of livelihood, species and ecological function, and cultural
and recreational needs can begin to address current global challenges (O'Farrell and
Anderson 2010). Unfortunately, scientific studies that examine the multifunctionality of
projects have been rare to date (Yang, Li and Li 2013). Both multifunctionality and
regenerative design can be applied to improve ecosystems and the services they
provide in urban areas.
HISTORY OF COMMUNITY LANDSCAPE TREATMENTS
"'Nothing is more pleasan t to the eye than green grass kept finely shorn' (Francis
Bacon 1561-1626)'' (Trudgill, Jeffrey and Parker 2009).
The objectives of designing with nature, establishing regenerative systems, and
integrating multiple functions into a single swath of land can be achieved. However,
contemporary preferences for landscape treatments consisting predominantly of turf
grass means that promoting treatments that enhance ecosystem services requires
challenging the dominant view of what should be planted. The history of turf grass and
its rise in popularity bears examination before alternate landscape treatments that
promote ecosystem services are proposed.
How did the predominant landscape treatment choice become grass? Thomas
Jefferson is credited for creating the first grass front lawn at his Monticello home in
Virginia (Kaufman and Lohr 2002). By the mid-1800s, garden magazines and writers
were encouraging homeowners to cultivate a "living green carpet (Kaufman and Lohr
2002). Andrew Jackson Downing, considered to be the forefather of landscape
architecture, published landscape guidelines that firmly established single family
homes surrounded by lawns and gardens as the dominant residential landscape by the
1840s (Larson, Casagrande, et al. 2009). Subdivisions such as Frederick Law Olmsteads
Riverside community furthered the popularity of this tradition, featuring homes that
were set back from the street and consisted of lawns and trees in order to mimic a
pastoral scene (Kaufman and Lohr 2002).
In the 1950s, authors such as Henry Aul, Assistant Horticultural Editor for The
New York Herald Tribune galvanized cultural norms around grassed front lawns. Ault
called "an open lawn, unencumbered by excess planting...one of the best ways to treat
the area between the front of the house and public sidewalk or street (Aul 1959, 29).
For aesthetic reasons, Ault strongly discouraged the use of other vegetation except in
limited circumstances: "The shrubs and small trees many gardeners are inclined to
scatter about the lawn may be collected into borders along the side lines and front
corners of the property, leaving the open lawn to sweep up to them and to the planting
around the house (Aul 1959, 30).
After decades of promoting the grassy front lawn, turf grass now covers
extensive swaths of land. Residential and commercial turf grasses, when combined, now
constitute "the largest irrigated crop in America, covering over 16 million hectares of
which 10 million hectares is residential lawn (Bormann etal., 2001; The Lawn
Institute, 2010) (Simmons, et al. 2011). But there are other treatment options that offer
greater returns with regard to promoting the ecosystem services upon which humans
rely, and their value can sometimes be overlooked in favor od planting the status quo
turf grass. Vegetative treatments that will be examined in this paper include turf and
native grasses, flowering and non-flowering vegetation, shrubs, trees, fruit and
vegetable-bearing plants, and preserving native vegetation. Recommendations will also
be made for non-vegetative treatments including fencing, water retention and
detention, impervious areas, irrigation, mulch, and pesticides and fertilizers.
"A thing is right when it tends to preserve the integrity, stability, and the beauty of
the biotic community. It is wrong when it does otherwise'' Leopold 1996, p. 262 in
(Kaufman and Lohr 2002).
Ecosystems, defined as "dynamic complexes] of plant, animal, and
microorganism communities and the nonliving environment interacting as a functional
unit, have been studied by scientists for hundreds of years (Millennium Ecosystem
Assessment 2005). In urban and suburban communities in particular, a critical question
is how nature and people are interconnected and interact. In 2015, the
Intergovernmental Platform on Biodiversity and Ecosystem Services (IPBES) developed
a conceptual framework that demonstrates this relationship.
Figure 1: IPBES Framework on relationship between nature & human well-being.
The panel begins with nature, which is defined as the "natural world with an
emphasis on the diversity of living organisms and their interactions among themselves
and with their environment (Intergovernmental Platform on Biodiversity and
Ecosystem Services 2015, 4). Nature's benefit to people consists of ecosystem goods and
services. These benefits influence the establishment of a good quality of life, or human
wellbeing (Intergovernmental Platform on Biodiversity and Ecosystem Services 2015).
Anthropogenic drivers, or the influence of humans, then become a factor influencing
nature once again.
Natures benefit to people is often described as a set of ecosystem services which
are "the benefits that flow from nature to people, e.g., nature's contributions to the
production of food and timber; life-support processes, such as water purification and
coastal protection; and life-fulfilling benefits, such as places to recreate (Donovan,
Goldfuss and Holdren 2015,1). Authors McDonough and Braungart describe their
dislike of the term "services, since "nature does not do any of these things just to serve
people (McDonough and Braungart 2002, 80). Rather, they encourage thinking about
ecosystem processes as part of a "dynamic interdependence, in which many different
organisms and systems support one another in multiple ways (McDonough and
Braungart 2002, 80). Due to the large volume of literature and the prevalence of the
term, this paper will continue to reference natures benefit to people as ecosystem
The full range of ecosystem services is divided into those that play provisioning,
regulating, cultural, and supporting roles. Provisioning services provide human beings
with the essentials of life, which include food, fresh water, wood and fiber, and fuel.
Regulating services contribute to maintaining a balanced ecosystem, and regulate
climate, food, disease, and water. Cultural services provide humans with aesthetic,
spiritual, educational, and recreational benefits. Finally, supporting services ensure that
the most basic components, or building blocks, of ecosystems are managed. Supporting
services are indirect in their benefits, as they support the functioning of the ecosystem
that allow for the other three types of services to directly benefit humans. Supporting
services include nutrient cycling, soil formation, and primary production. Urbanization
has put stress on ecosystems through changes in local land use and surface cover; by
introducing non-native or invasive species; by introducing fertilizer use, pest control,
and irrigation; by harvesting resources; and by contributing to climate change
(Millennium Ecosystem Assessment 2005). The last fifty years have seen a rapid and
extensive change in global ecosystems, which has significantly degraded species
diversity. According to the Millennium Ecosystem Assessment, "approximately 60% (15
out of 24) of the ecosystem services examined during the Millennium Ecosystem
Assessment are being degraded or used unsustainably, including fresh water, capture
fisheries, air and water purification, and the regulation of regional and local climate,
natural hazards, and pests (Millennium Ecosystem Assessment 2005,1).
As urbanization continues, land continues to be developed to serve industrial,
commercial, or residential uses. The landscape treatment choices surrounding these
uses can, with some planning, integrate natural ecosystem preservation and replication
into their design and management. The most effective option in designing and
managing landscapes to support ecosystem services is to retain as much high value pre-
disturbance, natural landscaping as possible (McHarg 1969). Where this is not possible,
landscape designs can utilize elements that are selected based on what they can
provide, be it cooling properties, air filtering, carbon intake, preventing soil erosion,
supporting wildlife, protecting water supply, reducing stormwater runoff, conserving
energy, and providing for the psychological needs of inhabitants (Abbey 1998) (Martz
and Morris 1990). If the built environment can support and provide even a small
portion of its own ecosystem services, pressure is reduced on other ecosystems, which
may allow them to regenerate (Zari 2015).
Ensuring that ecosystem services are being protected and fostered has become a
new arena of research (Elmqvist, et al. 2015) (Intergovernmental Platform on
Biodiversity and Ecosystem Services 2015) (Zari 2015) (TEEB The Economics of
Ecosystems and Biodiversity 2011) (Millennium Ecosystem Assessment 2005). In
October 2015, the United States federal government published a memorandum
directing federal departments and agencies to incorporate ecosystem services into
federal decision-making (Donovan, Goldfuss and Holdren 2015).
The Millennium Ecosystem Assessment has identified thirty-one services
provided by ecosystems. However, not all ecosystem services can be easily integrated
into areas of human settlement. Some provisioning services, such as fiber production
and the development of genetic resources, require large swaths of land, or intensive
uses of land that cannot be achieved on residential or commercial lots. Supporting
services, such as soil formation and photosynthesis, do not directly support humans
and operate at a micro scale that makes it difficult for municipalities to develop
regulations or incentives around them. While some cultural services can be addressed
generally, they also possess an intangible quality that cannot be as easily quantified and
regulated in the same way that air quality, climate, and other regulating services can.
Therefore, many cultural ecosystem services have been combined and are addressed
together, rather than individually. The services addressed this paper are highlighted in
bold in the table below.
Table 1: Ecosystem Services Described by the Millennium Ecosystem Assessment
Provisioning Regulating Cultural Supporting
Food Air quality regulation Cultural diversity Soil formation
Fiber Climate regulation Spiritual and religious values Photosynthesis
Fuel Water regulation Knowledge systems Primary production
Genetic resources Erosion regulation Educational values Nutrient cycling
Biochemicals, natural medicines, pharmaceuticals Water purification and waste treatment Inspiration Water cycling
Ornamental resources Disease regulation Aesthetic values
Fresh water Pest regulation Social relations
Pollination Sense of place
Natural hazard regulation Cultural heritage value
Recreation and ecotourism
The following sections describe the ecosystem services that are most applicable
to land in communities with varying levels of density. Although ecosystem services are
traditionally grouped by their function (provisioning, supporting, regulating, and
cultural), this paper distinguishes between ecosystem services that are consumed
locally in the community, regionally, or globally. Community-level services, consisting of
services that benefit the inhabitants within a particular municipality or county, include
food provision, erosion and soil health, moderating microclimates, and providing
cultural services.. Regional-level services benefit more than one locality, and can benefit
a geographic region of hundreds of miles in diameter, include stormwater
management/water quality, water availability/aquifer recharge, wildfire hazard
reduction, air quality, and pollination and wildlife habitat. Finally, the ecosystem service
of carbon sequestration affects human settlements the world over because it
contributes to the reduction of climate change, and is considered a global service.
The services that ecosystems provide can often be realized at the local level. The
ability of residents to see the effects of ecosystem services in the form of lowered
temperatures, the production of food, the reduction of soil erosion, or the promotion of
aesthetic or cultural values can help justify the installation of landscape treatments that
promote such services.
"Why maintain a large expanse of grass that you just have to mow and water when
you could turn that space into a productive food garden that can feed your family?" (City
of Minneapolis 2015).
The question raised by the City of Minneapolis aptly addresses the opportunity
for assessing the "highest and best use of a landscaped area by replacing turf grass
with agricultural treatments. The concept of "urban agriculture refers broadly to
"growing and raising food crops and animals in an urban setting for the purpose of
feeding local populations (Goldstein, et al. 2011).
This paper focuses primarily on the vegetative aspects of urban agriculture that
are most closely related to landscape regulations or incentives. Urban agriculture
activities involving planted vegetation can include the cultivation of vegetables,
medicinal plants, spices, mushrooms, fruit trees, ornamental plants, and other
productive plants (Lin, Philpott and Jha 2015). Urban gardens can take several forms,
including community gardens, private gardens (using in-ground or raised beds),
greenways (vegetated strips of land between sidewalks and streets), rooftop gardens,
and community orchards (Lin, Philpott and Jha 2015).
Urban agriculture supports many activities, such as promoting health,
supporting economic and community development, producing culturally valuable foods,
reducing the impact of local food deserts, and educating young people about growing
food (Mukherji and Morales 2010). Vegetable gardening, in particular, can also
supplement the lack of global fruit and vegetable supplies. According to a recent study,
"Overall, the global supply...of available [fruits and vegetables] falls 22% short of
populations need according to nutritional recommendations, and as much as 95%
short in some countries.... (Siegel, et al. 2015). Informal farming efforts such as
subsistence farming and urban gardens can help close this gap. How much produce can
urban gardens produce? A study conducted in Guelph, Ontario, determined that
household vegetable gardeners produced an average of 1.43 kilograms of produce per
square meter, and the top 10% yielded an average of 4.18 kilograms of produce per
square meter (CoDyre, Fraser and Landman 2015, 75). To significantly impact food
production in an urban area, both the skill level of gardeners and an increase in farmed
land is necessary (CoDyre, Fraser and Landman 2015). Further, more research at the
local level can help determine which crops are the most beneficial from a human
consumption/value standpoint. In Ontario, Canada, cucumbers were determined to be
more productive in residential gardens than in conventionally-produced vegetable
farms (CoDyre, Fraser and Landman 2015).
The benefits of urban agriculture extend beyond food production to other
ecosystem services. Planting vegetable gardens that "include fruit/seed-bearing plants,
limiting the use of pesticides and herbicides, and constructing compost heaps and bird
tables can foster wildlife by increasing bird and vertebrate abundance and diversity
(Lin, Philpott and Jha 2015,194). Pollination is supported through flowering plants and
climate regulation can be a result of the vegetative cover that edible landscapes provide
(Lin, Philpott and Jha 2015).
Challenges to urban agriculture include contaminated soil, which may be
prevalent in urban areas. A solution to this includes raised beds or soil remediation
(Mukherji and Morales 2010). Urban agriculture may also increase invasive weeds,
pathogens, or pests that could be detrimental to native species (Lin, Philpott and Jha
2015). In non-organic vegetable gardens, an increase in the use of herbicides,
pesticides, and fertilizers may reduce water quality.
Regulating Erosion and Soil Health
Preventing soil erosion and promoting soil health are ecosystem services upon
which many aspects of landscaping rely. Globally, agricultural practices are the greatest
contributors to erosion and degraded soil health (Millennium Ecosystem Assessment
2005). In urban areas, however, erosion occurs during the construction of new
development, and when areas of land do not possess vegetative cover or mulch.
As soil erosion leads to degraded water quality, many stormwater management
plans require erosion control measures for new construction. After construction,
vegetating landscapes is an effective approach to prevent erosion (Millennium
Ecosystem Assessment 2005) as trees and other vegetation bind soil particles to their
roots, thereby holding the soil together and in place (Martz and Morris 1990).
The Xeriscape approach to landscaping recognizes that making improvements to
the soil is important for promoting moisture penetration and retention (Ball 1990). One
way to improve soils is to use composted organic material. Allowing and encouraging
on-site composting is an approach that reduces waste that may otherwise end up in
landfills while enabling greater amounts of organic material to be added to a sites soil.
Mulch serves soils in a number of ways, as it not only reduces erosion, but the
decomposition of mulch improves underlying soil as well if organic mulch is used.
Further, mulches reduce weed growth, which can result in reduced use of pesticides
As humans produce more and more carbon, climactic changes are occurring that
can be felt globally. Scientists have determined that "[ejarth's average temperature has
risen by 1.5F over the past century, and is projected to rise another 0.5 to 8.6F over
the next hundred years (U.S. Environmental Protection Agency n.d.). Climate change
affects humans directly through thermal stress that can result in illness or death;
microbial and pathogen proliferation; impaired crop, livestock and fisheries yields that
lead to increased famine; and loss of livelihood leading to increased poverty. Climate
change has also resulted in increased severe weather and natural disasters such as
floods and droughts (U.S. Environmental Protection Agency n.d.).
A changing climate is resulting in warmer average temperatures in cities
(Hunter 2011). Urban areas can also be subject to the heat island effect, where the
amount of asphalt, concrete and built surfaces absorb the heat of the sun and increase
temperatures. Vegetation can play a role in reducing temperatures, which can translate
to a reduction in energy needs for cooling (Elmqvist, et al. 2015).
Trees, for example, can reduce temperatures through transpiration (Erell,
Pearlmutter and Williamson 2011). A study conducted in Manchester, United Kingdom,
show that a 10% increase in tree canopy cover may result in a 3-4 degree Celsius
decrease in ambient temperature (Elmqvist, etal. 2015). However, tree species from
hot or arid habitats or those with smaller leaves may have lower evapo-transpiration
rates than broad-leafed trees (Erell, Pearlmutter and Williamson 2011). Also, most
vapor transfer from leaves occurs at the top of the canopy during photosynthesis (Erell,
Pearlmutter and Williamson 2011). This results in little cooling effect on the air near
ground level. Therefore, the cooling of air under trees is primarily a function of surface
shading, where the tree crown and leaves absorb solar radiation that would otherwise
have been absorbed at ground level (Erell, Pearlmutter and Williamson 2011).
Grass and vegetative ground cover can improve a pedestrians thermal comfort
in a variety of ways. Grass, as compared with concrete, has a low albedo and will reflect
less short-wave radiation on to the pedestrian. A well-watered lawn can produce
evaporative cooling effects, though this can be at odds with water conservation
measures and may only cool three feet or less above the ground. Finally, well-vegetated
ground surface can channel latent heat from its surface into evapotranspiration,
resulting in a lower surface temperature for the vegetation itself (Erell, Pearlmutter and
While not a direct outdoor benefit, vegetation such as trees, shrubs and vines can
also influence indoor climates and therefore contribute to reduced energy consumption
inside buildings themselves. In cold climates, deciduous trees are preferable as they
provide shade in summer and lose foliage in winter, therefore allowing the sun to
penetrate. Foliage that produces a full shade effect can reduce the surface temperature
of a wall by as much as 10 degrees. Some drawbacks to using vegetation to reduce
energy consumption in buildings include: thick foliage that shades the structure during
the day can expose the building to relatively warm foliage at night, which can keep the
structure warmer than if it was exposed to cooler sky temperatures; and plants can
reduce wind speed near buildings which can reduce the potential for ventilation (Erell,
Pearlmutter and Williamson 2011). These considerations should be taken into account
when developing landscaping plans to reduce indoor energy costs for heating and
The first approach to moderate microclimates is to retain as many existing trees
on site as possible. A study that compared The Woodlands, a planned community in
Texas which required preservation of more than 25% of the natural forest stand with
two similar sites determined that although The Woodlands development area and
impervious coverage are much higher than the two similar sites, the preserved forest
mitigated the urban heat island effect to a greater extent (Yang, Li and Li 2013).
In order to remain resilient in the face of increased average temperatures, plants
themselves need to be able to withstand changing temperatures. Hunter (2011)
recommends an adaptive strategy for urban planting design that considers plant
plasticity, or "how well species perform across a range of environmental conditions
(174). A proxy for this is plant hardiness zone, and choosing plants with the greatest
zone range can increase the likelihood that the plant survives in a changing climate
One landscape option to be avoided is "zeroscaping, or rockscaping a property,
in which vegetative cover is replaced with non-organic rocks and other cover. Whether
to reduce maintenance time and costs or outdoor water use, this approach can reduce
property values (Ball 1990). Further, fully graveled landscapes appear "harsh and hot,
decrease noise or wind buffering, and can cause in-house temperatures to increase by
10-15%, leading to increased energy costs (Ball 1990).
Social Relations and Cultural Identity
Many aspects of social relations, creating a sense of place, and cultural identity
are found in our cities residential front yards, parks, and planted boulevards.
Some plant species become a symbol or signature of a particular place, such as
palm trees in warm climates or heather in the Scottish highlands (Hunter 2011). In
some cases, a communitys cultural or historic landscaping "norm has been cultivated
by years of public relations messaging from tourism boards. For example, the City of
Phoenix, Arizona promoted the slogan "do away with the desert in the 1900s and
launched a more recent "desert is a myth campaign to encourage residents and tourists
alike to view Phoenix as an oasis of lush vegetation amidst a desert surrounding
(Larson, Casagrande, et al. 2009). This type of messaging can influence residents
priorities for landscaping.
Planting ornamental, non-native species has its roots in place identity, or
attempting to recreate the familiar landscape from where they migrated (Hunter 2011).
In a study on front yard preferences, residents expressed a desire to replicate
landscapes from when/where they grew up in new locales, regardless of climate
differences (Larson and Brumand 2014).
The presence of vegetation also affects urban crime. A study published in 2012
demonstrated that in the City of Baltimore, a 10% increase in tree canopy was
associated with a roughly 12% decrease in crime (Troy, Grove and O'Neil-Dunne 2012).
The cultural ecosystem services that landscapes provide can sometimes be in
conflict with provisioning and regulating ecosystem services. Examples include the
tension between the aesthetic beauty of turf grass or particular plant species and water
conservation, and between cultural preferences for non-native ornamental species and
the harm caused by said species when they become invasive to the local ecosystem.
Social norms, historical preferences, and cultural identities can, to a large extent,
determine the level of success that can be achieved when attempting to introduce a new
approach to landscaping into a community. To explore the psychology of landscaping,
numerous studies and surveys have been conducted that ask participants to express
their preferences for particular types of residential yards such as traditional mesic
turfgrass, oasis mix, and low-water xeric (Larson and Brumand 2014) (Hayden, et al.
2015). Results demonstrate that residents are concerned about social pressures that
encourage "neatness and conformity to neighborhood style, particularly in front yards
(Larson and Brumand 2014) (Hayden, etal. 2015). In historic neighborhoods, residents
viewed the landscaping to be part of the areas heritage, and were reluctant to make
When balancing multiple desires, aesthetics played a primary role in landscape
decisions while environmental, cost, and maintenance concerns were secondary
(Hayden, et al. 2015). Norms about the rights and responsibilities of property owners
and other stakeholders also comes into play here, with most discussion weighted
towards rights rather than responsibilities.
As social and cultural norms and place-based identity differ greatly among
various geographic locales, it is difficult to analyze and recommend particular landscape
options. Certainly lawns offer recreational opportunities and contribute to
psychological well-being (Kaufman and Lohr 2002). However, due to their negative
impacts on provisioning ecosystem services, they should only be encouraged where
recreational activities will actually occur.
To the extent that particular plant species contribute to a sense of place,
alternative species with a similar aesthetic presence that are more resilient to climate
change should be added to landscape designs (Hunter 2011). For example, American
Basswood, a tree that fosters a sense of place in Southeast Michigan, is likely to
disappear from the area due to climate change. Beginning to plant White Basswood, an
ecologically and aesthetically similar tree that is adapted to a warmer climate, can help
preserve the sense of place in this region (Hunter 2011).
Messaging from water providers, municipal and county governments, and
common interest communities can help establish a new norm regarding socially and
culturally appropriate practices. California, with its ongoing multi-year drought, has
turned to messaging in order to encourage water-conserving landscape choices. A
recent study conducted by the Association of California Water Agencies showed that
California voters preferred the slogans "Stay golden, California and "fade to gold to
"brown is the new green to promote water reductions of lawns and landscapes
(Megerian 2015). On the other end of the spectrum, governments and organizations can
also ascribe negative connotations to undesirable landscaping practices. Rather than
framing landscape decisions as up to the personal preferences of property owners,
using phrases like "inappropriate landscapes, "improper use of plants, "water-hungry
plants, and "artificial landscapes helps convey the intent of local government
regarding landscaping priorities (Ball 1990).
Regional Ecosystem Services
Ecosystem services that are regional in nature benefit a greater geographic area
and typically more than one town or city than those that primarily provide localized
benefits. The ecosystem services described in this section rely on hydrological and
atmospheric processes, and therefore spread outside of community boundaries. They
include stormwater management, water quality and quantity regulation, wildfire
hazard prevention, air quality, and promoting pollinators and wildlife.
Excess water accumulated during heavy or prolonged precipitation events poses
a threat to the health, safety and welfare of our communities. This section describes the
ways in which landscaping can both allow the absorption of stormwater locally and
improve the quality of stormwater runoff.
As urban areas have increased in size and quantity, so too has the amount of
impervious surfaces such as structures, concrete, and asphalt covering the ground. This
leads to increased volumes and rates of stormwater runoff from properties, which
contributes to flooding and degraded water quality. Rather than conveying stormwater
away from a site as quickly as possible, new modes of thinking about stormwater
management has become "the art and science of mimicking nature to counter the effects
of land disturbance and impervious cover by conveying, retaining, infiltrating, and
treating stormwater where the runoff originates, and using vegetation to slow and treat
the water (Randolph 2012). This reduces the need for engineered drainage solutions
(Martz and Morris 1990).
While stormwater is typically addressed at the municipal level in stormwater
management plans, guides, and ordinances; stormwater best management practices can
be incorporated into landscape designs for properties ranging from big box stores to
single family residential. These include rain gardens, bioswales, and pervious
pavement, collectively often referred to as "green infrastructure. Developing green
infrastructure rather than traditional "grey infrastructure (usually heavily engineered
pipes, storage, and treatment facilities) avoids costly, space and energy-intensive
infrastructure such as sewers and stormwater treatment plants by conveying, treating,
and storing the water on site using natural systems.
The New Hampshire Department of Environmental Services (NHDES) developed
a "Homeowners Guide to Stormwater Management: Do-It-Yourself Stormwater
Solutions for Your Home in 2011 that recommends the following Best Management
Practices (BMPs) to reduce stormwater runoff and increase water quality:
Dripline infiltration trenches (a small trench below the roof line of a home to
collect and absorb stormwater);
Driveway infiltration trenches (a trench adjacent to a driveway to collect and
Dry wells (a deep hole filled with gravel to collect and absorb water from
Infiltration steps (steps to slow and infiltrate water on slopes of 45 or less);
Pervious walkways and patios (using brick pavers with a stone reservoir to
allow stormwater infiltration);
Rain gardens (a bowl-shaped garden that uses soil, mulch, and plants to collect
and absorb stormwater);
Vegetated swales (a shallow vegetated channel that slows stormwater runoff
and directs it to an area where it can infiltrate); and
Water bars (intercepts and diverts water traveling down moderately steep
walkways into vegetated areas) (McCarthy 2011).
Of these best management practices, rain gardens and vegetates swales are the most
multifunctional, as they use vegetation, which provides other ecosystem services, to aid
in stormwater management and water filtration.
Notably, the amount of impervious surfaces "continues to be the single most
important variable that defines the amount of urban development and predicts runoff
volume (Yang, Li and Li 2013, 5440). Therefore, initiatives to prevent or reduce
impervious areas or replace them with pervious materials are valuable for reducing
Regulating Water Quality
Ecosystems play a role in providing natural water purification that humans
harness to obtain clean water for drinking or other uses. Many of the stormwater best
management practices above serve a water purification function. This section focuses
on other means of ensuring that water quality is not degraded, namely reducing the
levels of contaminants leaching into groundwater.
The recognition that fertilizer and pesticide use poses a big challenge to water
quality in the watershed is no longer a novel concept (Ball 1990), though pesticides
were not always regarded with this level of caution. In his 1956 book "A Guide to Home
Landscaping, Donald Bushey, Professor in the Department of Floriculture and
Ornamental Horticulture at Cornell University writes that "A few years ago a dramatic
discovery was made, and home gardeners now have at their disposal a chemical that
kills some of the broad-leaved lawn weeds such as dandelion and plantain. It selects
these unwanted lawn weeds as its victim and does not damage the grass. This chemical
is 2,4-dichlorophenoxyacetic acid and is commonly known as 2,4-D (Bushey 1956, 79).
More than 35 years later, communities across the country were experiencing
contaminated groundwater supplies, with tests in over 25 U.S. states indicating that the
contamination resulted at least in part from fertilizers and pesticides (Ball 1990).
The Millennium Ecosystem Assessment has found that "[s]ince 1960, flows of
reactive (biologically available) nitrogen in terrestrial ecosystems have doubled, and
flows of phosphorus have tripled. More than half of all the synthetic nitrogen fertilizer,
which was first manufactured in 1913, ever used on the planet has been used since
1985 (Millennium Ecosystem Assessment 2005, 2). To improve water quality by
reducing inputs to the soil, organic amendments such as compost and organic mulches
can be utilized, and phosphorus-containing fertilizers can be reduced or eliminated.
Lawns can improve water quality through contaminant filtration (Kaufman and
Lohr 2002). However, turf grass also impacts water quality negatively. Lawn chemicals,
which cost Americans over $5.2 million in fossil fuel-derived fertilizers and $700
million of pesticides, contaminate the soil and groundwater (Kaufman and Lohr 2002)
(Simmons, et al. 2011).
Humans require water for both life-sustaining and everyday convenience needs.
We drink water, use water to prepare food, bathe ourselves and wash our clothing,
make products, and so forth. The world has a finite amount of water, and with growing
global population and regional drought, water is becoming more valuable and more
scarce. Treating water to make it potable and convey it to taps also requires chemicals
and energy. It is therefore a major challenge that in the United States, lawns account for
30-60% of municipal potable water use (Simmons, etal. 2011). Reducing a communitys
reliance on clean water by reducing the water use on landscapes can make them more
resilient to a future with fewer water resources.
Landscape treatments that reduce water use include reduction in the use of turf
grass, use of drought-tolerant species (often these are species native to the area),
water-efficient irrigation, the use of mulch, and proper maintenance.
In the past few decades, a program that blends many of these strategies called
Xeriscape was developed to promote landscape options that reduce water use. The
term xeriscape comes from the Greek word "xeros, meaning dry. Denver Water first
coined the term "xeriscape in 1981 with a simple and straightforward slogan: "water
conservation through creative landscaping (Ball 1990, v). The xeriscape process
follows seven steps: planning and design; soil improvements; limited turf areas; use of
mulches; use of low-water-demand plants; efficient irrigation; and appropriate
maintenance (Ball 1990). Benefits of xeriscaping, in particular, extend beyond water
conservation and can include reduced repair needs of asphalt road surfaces adjacent to
xeriscaped landscapes due to reduced water runoff, reduced energy needed to treat and
pump water, and reduced chemical use and costs due to reduced fertilizer application
and reduced water treatment needs (Ball 1990). The costs savings can be significant.
For example, a water utility that reduces its overall water demand by 20% and had used
15 million pounds of chemicals to treat water annually ($800,000) can see a savings of
$160,000 annually due to reduced chemical use (Ball 1990).
Challenges to xeriscaping include: keeping adequate inventories of drought-
tolerant species in stock, which could lead to the "raiding of native plants for use in
urban landscapes, and unintended side effects of particular plants (such as the ice plant
that has caused avalanches on hillsides because of their weight and shallow root
system) (Martz and Morris 1990). It is important to note that in the xeriscape program,
selecting low-water-demand plants does not necessarily mean selecting plant species
native to the geographic region (Ball 1990). Low-water-demand plants can be
regionally adapted but originate from other areas. This distinction may be in conflict
with wildlife habitat needs described earlier.
Some vegetation, such as trees, requires greater amounts of water than other
vegetation. This can lead to questions about the value or importance of trees relative to
the amount of water they require, particularly in drought-prone areas. However,
studies show that the use of shade trees or other shading elements can "significantly
moderate the rate of water loss from the grass to the atmosphere, and the resulting
water savings can far outweigh the irrigation requirements of the trees themselves
(Erell, Pearlmutter and Williamson 2011,183).
Regulating Wildfire Hazards
"Landscaping is pivotal to protecting homes from fire." (National Fire Protection
Association 2016, 3).
Natural hazards pose a great risk to life, property, and wellbeing. The Federal
Emergency Management Agency (FEMA) predicted in 2000 that 1 billion people die
each decade as a result of natural disasters (Randolph 2012). Monetarily, damages to a
community can add up, as it did as a result of Hurricane Katrina, where the total
damages amounted to $81 billion (Randolph 2012). Ecosystems have the ability to
moderate the occurrence, severity, and impact of natural hazards. For the purposes of
this paper, flood hazard mitigation is addressed in the water regulating section that
describes reducing stormwater runoff, and drought hazard regulation is addressed in
the water regulating section concerning reduced water use/availability. This section
focuses primarily on the risk of wildfire and its associated risk reduction strategies.
While wildfires have always been a threat to forests and other ecosystems,
urban sprawl into wildland areas has exacerbated this risk (Randolph 2012). In
California, for example, the annual number of acres burned as a result of wildfires has
increased from an average of 250,000 in 1990 to 1,000,000 in 2008 (Randolph 2012).
Lorraine Carli, Vice President, Outreach and Advocacy, for the National Fire Protection
Association notes that due to climate change, fires are occurring in parts of the country
that have traditionally not been susceptible to wildfire (National Fire Protection
Programs such as FireWise Communities have established guidelines for the
ways in which landscaping choices can reduce the risk of wildfires, including planting
fire-resistant landscaping and maintenance of wild vegetation that can serve as fuel in
the event of a wildfire. Some jurisdictions require defensible space to be established
around homes in the wildland urban interface, which can include areas of short,
herbaceous plants and deciduous trees and guidance on grasses, horizontal and vertical
clearance for shrubs and trees, and canopy pruning (Randolph 2012). The FireWise
Communities program recommends the following landscape treatments and
maintenance practices for Zone 1 (at least a 30 foot diameter around the house) of
properties in high wildfire-risk areas (National Fire Protection Association 2016, 4):
Space plants carefully, and use those that are low-growing and free of resins, oils
and waxes that burn easily.
Space conifer trees 30 feet between crowns.
Create a "fire-free area within five feet of the home, using non-flammable
landscaping materials and/or high moisture-content annuals and perennials.
Mow the lawn regularly.
Prune trees up six to ten feet from the ground.
Trim back trees that overhang the house.
Water plants, trees and mulch regularly.
ZONE 2, within 30-100 feet from the home, should consider the following (National
Fire Protection Association 2016, 4):
Plants in this zone should be low-growing, well irrigated and less flammable.
Leave 30 feet between clusters of two to three trees, or 20 feet between
Encourage a mixture of deciduous and coniferous trees.
Create "fuel breaks, like driveways, gravel walkways and lawns.
Prune trees up six to ten feet from the ground.
Recommendation for Zone 3,100-200 feet from the home, include (National Fire
Protection Association 2016, 4):
Thinning the area, although less space is required than in Zone 2.
Removing smaller conifers that are growing between taller trees.
Removing heavy accumulation of woody debris.
Reducing the density of tall trees so canopies are not touching.
Some of these risk-reduction landscaping strategies can come into direct conflict
with other priorities to enhance and promote ecosystem services through landscape
choices, such as tree planting to aid in microclimate regulation and carbon
sequestration. The National Fire Protection Association, in a 2013 guide, posits the
establishment of a weed ordinance as an alternative approach to defensible space
requirements (National Fire Protection Association 2013). In this strategy, not only
must properties be kept free of weeds, and vegetation determined to be a fire hazard is
required to be removed. Weed ordinances have the capacity to be used to remove
native grasses and vegetable gardens from residential landscaping. Careful
consideration must be placed on local context and the prioritization of community
needs regarding ecosystem services.
Regulating Air Quality
Air pollution, consisting of harmful gases such as nitrogen oxides, ozone, volatile
organic compounds and very small particulate matter (Trvainen, Pauleit, Seeland, & de
Vries, 2005), has harmful effects on human health. The World Health Organization has
determined that "[f]ine particulate matter is associated with a broad spectrum of acute
and chronic illness, such as lung cancer, chronic obstructive pulmonary disease (COPD)
and cardiovascular disease (World Health Organization n.d.).
Lawns can filter dust and pollen from the air (Kaufman and Lohr 2002). A 50 by
50 foot lawn can produce enough oxygen for a family of four (Kaufman and Lohr 2002).
However, the maintenance of turf grass contributes to air and water pollution, as it
usually requires the use of lawn mowers. Gas-powered mowers use 800 million gallons
of gasoline nationally (Simmons, etal. 2011). According to the Automobile Club of
Southern California, "[a] gasoline-powered lawn mower produces as much pollution in
one hour as a new car does in thirty hours (Kaufman and Lohr 2002).
Significant benefits can accrue from employing vegetation to reduce air
pollution. One tree, for example, can absorb 10 pounds of air pollutants a year, and
produce about 260 pounds of oxygen (American Forests n.d.). Fowler etal (2004)
determined that woodlands collect three times as much particulate matter as
grasslands (Forestry Commission n.d.). Coniferous trees have a greater filtering
capacity than deciduous trees, while deciduous trees are better at absorbing gases
(Stolt, 1982). Groups or rows of trees filter more dust than single trees, and trees are
most effective at capturing air pollution when planted closer to the source of pollution
(Tyrvainen, et al. n.d.). Plants with rough leaf surfaces can remove noxious particles
from the air (Martz and Morris 1990).
Regulating Pollinators and Wildlife
The loss of biodiversity globally is a major area of concern: across a range of
taxonomic groups, population size or range or both is in decline for the majority of
species (Millennium Ecosystem Assessment 2005). The distribution of species is
becoming more homogenous, or similar to each other because of the introduction of
non-native species (Millennium Ecosystem Assessment 2005). The species extinction
rate has increased by as much as 1,000 times and 10-30% of mammal, bird, and
amphibian species are currently threatened with extinction (Millennium Ecosystem
Assessment 2005). Genetic diversity, particularly among cultivated species, has
declined (Millennium Ecosystem Assessment 2005). These alarming statistics signal the
need to better consider species protection, which can be accomplished at a local scale
with wildlife habitat protection and restoration.
Protecting and restoring habitat for pollinators is particularly important. In May,
2015, the Presidents Pollinator Health Task Force released its National Strategy to
Promote the Health of Honey Bees and Other Pollinators, recognizing that "[hjoney bee
pollination alone adds more than $15 billion in value to agricultural crops each year,
and provides the backbone to ensuring our diets are plentiful with fruits, nuts, and
vegetables (Pollinator Health Task Force 2015, ii). While the Strategy mainly focuses
on federal actions and does not highlight landscape ordinances as a possible avenue for
strengthening the habitat and food sources of pollinators, it recognizes that "[t]he
actions of a single person can make a differenceevery citizen can contribute to
pollinator conservation and should have the opportunity to become engaged in ways
that are meaningful (Pollinator Health Task Force 2015,19). Some strategies, such as
HUDs commitment to "develop a notice to encourage grantees to incorporate new
pollinator habitats into existing and future projects, and to adjust their landscaping
procedures to reduce mowing, plant native species, and review pesticide usage could
be applied on a state or local level (Pollinator Health Task Force 2015, 41). Pesticide
use pays a major role in the decline of pollinators, and the decline in milkweed, an
essential food for monarch butterflies, is a result. EPA has pledged to take actions, as
part of its regulatory decisions and voluntary programs, to establish practices and
requirements to protect critical milkweed resources (Pollinator Health Task Force
2015, 50). This is another strategy that could be undertaken on the local level.
The Pollinator Partnership, a non-profit organization whose mission is to
promote the health of pollinators through conservation, education, and research,
provides eco-regional guides that assist in the selection of plants beneficial to
pollinators (Plant Pollinators n.d.).
Habitat protection planning has become an important component of community
development as the Endangered Species Act has matured. Community-wide protection
planning looks at land use patterns and develops strategies to preserve sensitive
habitat and promote wildlife corridors across its jurisdiction or region. Principles of
large-scale habitat protection can also be brought to the site level through the control of
pets, buffer requirements, maintenance of native plants in landscaping, and sensitive
lands overlays (Duerkson, etal. 1997).
As native vegetation may provide greater number of insect species for food and a
better breeding habitat for insect-eating songbirds, retaining pre-development plants
and habitat features such as fields and patches of trees and shrubs should be preserved
to the greatest extent possible (Duerkson, et al. 1997).
When plantings do occur, bird species can benefit greatly from landscape
considerations that include an abundance and variety of native ground covers, shrubs,
and trees in vertical and horizontal plant configurations to provide persistent fruits and
seeds for foraging; nesting sites; and cover to reduce the risk of predation (Duerkson, et
al. 1997). Not only should nectar-producing plants be included in landscape decisions,
but the timing of nectar flow should be considered to offer the greatest benefit to
pollinators throughout the season (Hunter 2011).
While bluegrass lawns may provide feeding opportunities to ground-gleaning
omnivores, small mammals prefer concentrated areas of trees, shrubs, and weedy areas
to scattered trees and mowed lawns (Duerkson, et al. 1997).
Whether living in a city, suburb, or rural area, areas designated for landscaping
can be developed in such a way that they promote wildlife. While urban areas will not
likely provide habitat for large animals, smaller wildlife (particularly bees, moths,
wasps, flies, beetles, mammals, birds, reptiles and amphibians) can thrive (National
Wildlife Federation n.d.). The National Wildlife Federation has developed a certification
program that is based on providing a wildlife-friendly garden or yard through the
Provide Food: Plant native forbs, shrubs, and trees in order to provide foliage,
nectar, pollen, berries, seeds, and nuts. For example, Monarch butterflies require
the host plant milkweed in order to eat and reproduce. To become certified, the
yard habitat must incorporate 3 types of plants or supplemental feeders from a
list including berries, nectar, seeds from a plant, foliage/twigs, nuts, fruits, sap,
pollen, suet, bird feeder, squirrel feeder, hummingbird feeder, butterfly feeder.
Supply Water: install bird baths, puddling areas for butterflies, ponds, or rain
gardens. For certification, a yard must include one of the following: birdbath,
lake, stream, seasonal pool, ocean, water garden/pond, river, butterfly puddling
area, rain garden or spring.
Create Cover: use native vegetation, shrubs, thickets, brush piles, or dead trees.
Two places to find shelter must be present for certification, from the following
list: wooded area, bramble patch, ground cover, rock pile or wall, cave, roosting
box, dense shrubs or thicket, evergreens, brush or log pile, burrow, meadow or
prairie, water garden or pond.
Give Wildlife a place to raise their young: wildflower meadows and bushes for
butterflies and moths, caves for bats. Two places must be present for
certification, chosen from categories of mature trees, meadow or prairie, nesting
box, wetland, cave, host plants for caterpillars, dead trees or snags, dense shrubs
or a thicket, water garden or pond, or burrow.
Create a healthy habitat: use native plants, water conservation, and do not use
herbicides or pesticides. The program requires that two steps from following
three categories are needed to satisfy the sustainable gardening practices
section of the certification process For soil and water conservation options
include riparian buffer, capture rain water from roof, xeriscape (water-wise
landscaping), drip or soak hose for irrigation, limit water use, reduce erosion (i.e.
ground cover, terraces), use mulch, rain garden. For controlling exotic species,
practice integrated pest management, remove non-native plants and animals,
use native plants, reduce lawn areas. To promote organic practices eliminate
chemical pesticides, eliminate chemical fertilizers, and compost. (National
Wildlife Federation n.d.).
Global Ecosystem Services
Carbon sequestration, because of its link to climate change, is an ecosystem
service with the potential to affect communities globally.
Greenhouse gas emissions of carbon dioxide (CO2), methane (CH4), nitrous oxide
(N2O) and fluorinated gases contribute to the warming of the earths atmosphere on a
global scale. In 2011, carbon dioxide accounted for 84% of total emissions in the United
States (U.S. Environmental Protection Agency 2 n.d.). Various methods are being
considered to curb and decrease levels of atmospheric carbon (CO2), including the role
of vegetation in natural carbon capture and storage.
Terrestrial sequestration, as defined by the EPA, is "the process through which
carbon dioxide from the atmosphere is absorbed by trees, plants and crops through
photosynthesis, and stored as carbon compounds in biomass (tree trunks, branches,
foliage and roots) and as organic matter in soils (Reed n.d.). Forests have been
recognized as a carbon "sink due to their ability to sequester carbon from the
atmosphere. "Globally, forests contain more than half of all terrestrial carbon, and
account for about 80% of carbon exchange between terrestrial ecosystems and the
atmosphere. Forest ecosystems are estimated to absorb up to 3 Pg (3 billion tons) of
carbon annually (Montagnini and Nair 2004, 282). Montagnini and Nair (2004) define
three forms of activities in which forests manage atmospheric carbon: Carbon
sequestration (afforestation, reforestation, restoration, agroforestry), Carbon
conservation (conservation of existing forests and improved harvesting techniques),
and Carbon substitution (conversion of forest biomass to replace energy-intensive
Does carbon sequestration occur in urban areas? A study of a neighborhood in
Singapore determined that "vegetation captures 8% of the total emitted CO2 in the
residential neighborhood studied, and that "negative daytime CO2 fluxes...have been
observed during the growing season at suburban sites characterized by abundant
vegetation and low population density (Velasco, et al. 2013). In the United Kingdom it
was determined that well-treed areas sequestered more than twice the levels of carbon
as areas with poor provision of vegetation (Whitford, Ennos and Handley 2001).
McPherson, et al. (2005) measured the cost benefits of municipal forests in a selection
of western U.S. cities and determined that annual atmospheric CCh-reduction benefits
and air quality benefits averaged $l-$2 per tree (McPherson, et al. 2005).
Some challenges are involved in utilizing vegetation for carbon sequestration.
First, it is difficult to achieve a volume of vegetation needed to offset the amounts of
carbon released from fossil fuel processing and energy production facilities. For
example, 62 million ten-year-old trees would be necessary to offset 90% of the roughly
3 million tons of CO2 produced per year (U.S. Environmental Protection Agency 2 n.d.).
Second, the United Nations Intergovernmental Panel on Climate Change has
demonstrated the scale of the challenge by stating "it is likely that [Carbon Dioxide
Removal] would have to be deployed at large-scale for at least one century to be able to
significantly reduce atmospheric CO2 (Intergovernmental Panel on Climate Change
While vegetation contributes to carbon sequestration, the type of vegetation
yields different levels of sequestration. "Planting designs that substitute trees and
flowering shrubs in lieu of herbaceous perennials will increase carbon sequestration,
and the transformation of lawns to low-input native species gardens will reduce
greenhouse gas-emissions (Hunter 2011,189).
REGULATORY AND INCENTIVE BEST PRACTICES
Since many benefits of ecosystem services accrue to a community or region at
large and not to the individual property owner, it may be necessary for a local
government to intervene in the decisionmaking process in the public interest (Jack,
Kousky and Sims 2008). Once a local government has information about the landscape
treatments that most effectively promote ecosystem services, the next step becomes
establishing regulatory measures or voluntary programs that most effectively promote
the use of the effective treatments and discourage treatments that are detrimental.
Codifying rules and developing programs that benefit ecosystem health can be
developed in various ways, based on the way that a governments existing regulations
and programs are structured. A single regulation or program is unlikely to provide
guidance on all considerations regarding the most beneficial uses of urban land. Rather,
such guidance may be found in a combination of land use code sections such as a
landscape ordinance, urban agricultural ordinance, or fertilizer ordinance; a monetary
exaction such as stormwater utility fees and water pricing; or voluntary programs such
as rebates or public awareness campaigns.
Codes and Ordinances
Many municipalities and counties have developed ordinances, standards, or guidelines
that can apply to ecosystem services and their required/preferred application.
The earliest known ordinance that addresses landscaping is the Pennsylvania
Shade Tree Law of the eighteenth century, which states that "every owner...of every
house...shall plant one or more trees...before the door of his, her or their house...not
exceeding eight feet from the front of the house...to the end that the said town may be
well shaded from the violence of the sun in the heat of summer and thereby be
rendered more healthy (Abbey 1998, 7). Modern day tree ordinances fall into several
categories: street tree ordinances, which preside over trees within public rights-of-way;
tree protection ordinances, which protect native trees or those with historical
significance from being removed; and view ordinances, which address resolution of
conflicts between property owners regarding trees. Street tree ordinances primarily
cover the planting and removal of trees within public rights-of-way (Swiecki and
Landscape ordinances, which cover landscape treatments beyond trees, became
popularized in the 1970s. Landscape ordinances typically prescribe post-construction
landscaping requirements. They often mandate that certain amounts or areas of land
remain open and be planted with trees, shrubs, and ground cover. Such ordinances can
deal with single issues such as landscaping parking lots or using landscape treatments
to buffer incompatible uses, or can address multiple issues that encompass design,
installation, and maintenance of post-construction landscaping. Design requirements
for fences and walls, earth berms, drainage features, irrigation and maintenance can
also be included (Abbey 1998). A comprehensive land ordinance can prevent site
clearing and habitat destruction (land alteration during construction) in addition to
specifying landscaping, tree removal, stormwater management, erosion control, and
ground water recharge requirements post-construction (Abbey 1998, 3).
Government regulation of landscaping has been legally upheld. In 1949, a court
of law upheld planting requirements that mandated a ten-foot strip along the back of
lots be reserved for planting trees or shrubs to reduce the effects of traffic on the
adjacent boulevard in Ayres v. City of Los Angeles (Abbey 1998).
Submittal requirements for landscape ordinances vary by jurisdiction. Common
1. Location, type, and quality of existing vegetation; what vegetation is to be saved;
and by what methods.
2. Locations and labels for all proposed plants.
3. Plant lists or schedules with plant name, quantity, spacing and size of all
4. Location and description of other non-vegetative landscape improvements.
5. Planting and installation details necessary to fulfilling standards (Martz and
Other types of ordinances have also been adopted to address various aspects of
ecosystem services. These include ordinances prohibiting the use of phosphorus-based
fertilizers, promoting urban agriculture, requiring soil erosion and sedimentation
control, and so forth. These ordinances typically take up only a small number of
ecosystem services, and should therefore be examined as part of a wholesale review of
regulatory measures that influence the selection of treatments for residential and
Exacting a fee for detrimental behavior is another approach to protecting or
enhancing ecosystems in urban areas. Fees are commonly exacted for stormwater
management, in which individual property owners are charged a fee to help pay for the
cost of collecting, conveying, and treating stormwater. These stormwater user fees
(SUFs) also help local governments comply with the Clean Water Acts 1987 Water
Quality Act stormwater provisions and incentivize the reduction of impervious surfaces.
Fees can be collected monthly or annually, and rates can be flat or calculated based on
amount of impervious area on the property or amount of runoff based on a selected
computation method (Kea 2015). When stormwater user fee rates are high enough and
calculated by the amount of impervious surfaces on the property, owners or residents
are incentivized to reduce or refrain from expanding the amount of impervious surfaces
in order to reduce or keep their fees low.
Permit fees for new construction, such as soil erosion control permits, and fines
for non-compliance also help to ensure that activities are being undertaken that reduce
damage to ecosystems.
When local governments seek a non-regulatoiy or fee-based requirement to
promote behaviors that enhance the provision of ecosystem services, they can develop
voluntary incentives or programs to achieve their goals. "Payment for ecosystem
services, or PES, is a strategy that includes incentive-based strategies including charges
(described above), subsidies, tradable permits (such as markets for trading pollution
reduction or development rights), and market friction reduction (educational programs
or modified rules) (Jack, Kousky and Sims 2008). PES can be developed as lump sums to
property owners for carrying out a particular action, can be a set rate for a scalable
action such as the number of trees planted or impervious pavement removed, or by
setting lower tax rates for property owners who carry out land uses that are beneficial
to ecosystem services (Jack, Kousky and Sims 2008).
In many cases, local governments will need to provide supplemental materials
such as design guidelines, manuals, and or other reference documents to strengthen
their regulatory or voluntary-based programs. Design guidelines recommend, but do
not require measures for fulfilling the desired design goals (City of Wheat Ridge 2012).
Communities with ordinances or standards may publish a landscape design manual that
includes plant lists, detailed specifications to accompany general standards, and
aesthetic recommendations to encourage pleasing landscape design applications (Martz
and Morris 1990).
The objective of this paper is not to recommend the specific applications
governments should utilize to implement best practices regarding ecosystem health on
urban land. Rather, it is to analyze and summarize current data on the effects of
common landscape treatments on ecosystem service provision so that governments
may integrate these recommendations into their regulatory and programmatic
framework using an integrated and holistic approach. The sections below describe
some of the more stringent, far-reaching examples of regulatory and incentive-based
programs that contribute to strengthening ecosystem services in urban areas. Notably,
local governments have not yet begun to explicitly address some ecosystem services
with regard to urban landscaping through regulations or incentive programs. These
include addressing air quality, sequestering carbon and moderating microclimates, and
social relations and cultural identity.
Urban gardening began in the United States in the late 1800s on vacant lots and
as school gardens, which led to the "civic improvement gardens inspired by the City
Beautiful movement (Mukherji and Morales 2010). During World War I, the Great
Depression, and World War II, urban food gardens were promoted to reduce food
scarcity (Mukherji and Morales 2010). However, in recent years, regulations have been
enacted that encourage orderly and clean landscapes at the expense of vegetable
gardens and other agricultural activities such as composting and possessing livestock
and bees (Mukherji and Morales 2010).
A number of U.S. cities are now recognizing the value of urban agriculture, and
have sought ways to encourage it through programs and regulations. Some of the most
comprehensive and far-reaching examples are described in detail below.
The City of Seattle, Washington held a "Year of Urban Agriculture in 2010. As a
result of this initiative, Seattle updated its municipal code with Ordinance 123378 to
better support urban agriculture (City of Seattle 2010). The Ordinance establishes that
an urban farm or community garden is permitted outright; sets forth new guidelines for
urban farms in residential zones regarding mechanical equipment, sales, deliveries,
motor vehicles, location, signs, and structures; requires the submission of an urban
farm management plan; enables the outright permitting of small animals, farm animals,
domestic fowl, and bees; sets forth requirements for community garden size and
structure height; and makes allowances for greenhouses (City of Seattle 2010). The
urban farm management plan must include a site plan, equipment, square feet of land-
disturbing activity, and a sediment and erosion control plan. Permit decisions are made
on potential impacts and mitigation of water quality and soils, traffic and parking, visual
impacts and screening, noise and odor, agricultural chemicals, and mechanical
equipment (City of Seattle 2010). As demonstrated by the City of Seattle, when
agricultural uses are regulated in codes, they typically address gardening at the urban
farm scale and do not necessarily include landscaping or gardening that is "incidental to
a residential use or business if plants or their products are not sold (City of Seattle
2010). In the case of residential or business use, vegetable gardening is often
considered to be a permitted use by right.
Municipalities can integrate urban agriculture into Planned Unit Developments
(PUD). Troy Gardens in Madison, Wisconsin is a PUD that has integrated community
gardens, an organic farm, and a Community Supported Agriculture program into its
development (Mukherji and Morales 2010).
In 2012, the City of Minneapolis adopted updates to its zoning code to encourage
urban agriculture. Notably, the City amended its section that required landscaping on
all areas not occupied by buildings, parking and loading facilities or driveways, to be
"covered with turf grass, native grasses or other perennial flowering plants, vines,
mulch, shrubs, trees or edible landscaping (Gordon 2012, emphasis added).
Most requirements for mitigating stormwater runoff are typically included in a
jurisdictions stormwater management plan or ordinance (and typically regulate new
construction and major renovations).
Best practices in encouraging voluntary homeowner landscaping that manages
stormwater also exist. The State of New Hampshire has a "Soak up the Rain program
aimed at residential homeowners. This program provides resources and technical
assistance to help homeowners install stormwater best management practices (BMPs)
on their properties. To complement the program, the New Hampshire Department of
Environmental Services (NHDES) developed a "Homeowners Guide to Stormwater
Management: Do-It-Yourself Stormwater Solutions for Your Home in 2011 that clearly
explains the steps necessary to assess and implement stormwater BMPs.
Developers can also integrate stormwater management into the design of new
subdivisions. In the 1970s, Ian McHarg designed The Woodlands community in Texas
around three stormwater management principles: land with high soil permeability was
preserved for open space and low permeability was used for development; more than
25% of the natural forest pre-development was preserved; and open drainage was used
instead of curb-and-gutter (Yang, Li and Li 2013). A 100-year and a 500-year storm
event demonstrated that the Woodlands received little property damage while Houston
(50km south) was severely flooded both times (Yang, Li and Li 2013).
Stormwater utility fees are another approach that local water utilities can use to
both fund stormwater activities and discourage the use of landscape treatments that
cause impervious surfaces on properties. According to the 2014 Western Kentucky
University Stormwater Utility Survey, of almost 1500 stormwater utilities in the United
States and Canada, the community of Golden Beach, Florida, with a population of about
940, has the highest monthly stormwater fee of $35 for an 8,000 square foot property
(Campbell, et al. 2014, 6). They established their stormwater utility in 1993. The
smallest community with a stormwater utility is Indian Creek Village, Florida with a
population of 88, and the largest was Los Angeles, with a population of over 3 million
(Campbell, etal. 2014,1).
To address the non point sources of pollution, some of the landscape strategies
used to treat stormwater such as rain gardens also serve to improve water quality.
Methods for addressing point sources of pollution in urban landscapes are also
beginning to be encouraged or mandated. In response to elevated levels of nitrogen and
phosphorous contaminating groundwater and surface water, several states,
municipalities, and counties have enacted bans on phosphorous-based fertilizers
Dane County, Wisconsin has a chapter in its code of ordinances that prohibits the
application of fertilizer "containing more than 0% phosphorus or other compound
containing phosphorus, such as phosphate (Dane County, Wisconsin 2011).
While not prohibiting phosphorus fertilizers outright, the State of Florida
developed a Model Ordinance for Florida-Friendly Use of Fertilizer on Urban
Landscapes in 2015 that regulates the proper use of fertilizers; establishes training and
licensing requirements; establishes a "prohibited application period (the rainy
season); and specifies fertilizer application rates and methods, fertilizer-free zones, low
maintenance zones, and exemptions (Florida Department of Environmental Protection
2 Eleven states as of 2012: Illinois, Maine, Maryland, Michigan, Minnesota, New Jersey,
New York, Vermont, Virginia, Washington, and Wisconsin.
The South Florida Water Management District was an early adopter of drought-
tolerant plants, and established a model landscape code in 1987 that promoted
economic and efficient water use, the protection and conservation of water resources
and the use of drought and flood tolerant plants (Schnelle 1987).
The State of California has established a robust approach to address water
conservation. In 2006, the Water Conservation in Landscaping Act (Assembly Bill 1881)
instituted a requirement that cities and counties adopt water conservation ordinances
by 2010. The California Department of Water developed a Model Water Efficient
Landscape Ordinance, adopted in 2009, to assist in the development of such ordinances.
On April 1, 2015, Edmund "Jerry Brown, the Governor of California issued Executive
Order B-29-15, which extended the State of Emergency due to severe drought
conditions and instructed the Department of Water to update the State Model Water
Efficient Landscape Ordinance to "increase water efficiency standards for new and
existing landscapes through more efficient irrigation systems, greywater usage, onsite
storm water capture, and by limiting the portion of landscapes that can be covered in
turf (Executive Department, State of California 2015, 3). The Executive Order also
required reporting on local ordinance implementation by December 31, 2015.
In some cases, the law must be clarified to remove barriers to landscape
treatments that provide ecosystem services. T o address concerns that Common
Interest Communities3 were restricting landscaping practices that promoted water
3 Common Interest Communities are subdivisions containing common land [often including recreational
amenities] typically owned by a Homeowners Association.
efficiency, the Colorado State Senate passed Bill 183 in 2013. This bill amended current
law to make clear that the covenants or declarations, bylaws, and rules and regulations
of common interest communities may not prohibit or limit xeriscape or drought-
tolerant vegetation or require ground covering vegetation to consist of any amount of
turf grass. Any attempts to do so are contrary to public policy and unenforceable. The
bill also adds a definition of "xeriscape" to the Colorado Common Interest Ownership
Act. According to the Bill, an Homeowners Association (HOA) may not prohibit the use
of xeriscape or other drought-tolerant vegetative landscapes to provide ground
covering and may not fine unit owners for violations of rules and regulations of the
association for failure to adequately water when water restrictions are in place and the
unit owner waters in compliance with those restrictions (State of Colorado Senate
2013). HOAs can, however, adopt and enforce design or aesthetic guidelines that
"require the installation of drought-tolerant vegetative landscapes; regulate the type,
number, and placement of drought-tolerant plantings; and regulate the hardscapes
(such as concrete patios, pavers, stone walls, etc.) that an owner may install
Wildlife and Pollinators
Recognizing the importance of native plants to wildlife habitat among other
things, the City of Scottsdale, Arizona adopted a Native Plant Ordinance. Adopted in
1981and revised several times since,4 the Ordinance ensures the protection of native
plants that already exist on land that is being developed. Any project that affects native
plants (trees with a 4 inch caliper or greater and cacti three feet or taller) from a list
4 Most recently in 2000.
specified in the code must submit a native plant program that describes how each
impacted plant will be addressed. Plants are intended to remain in place and if they are
unable to do so, must be salvaged and replanted within the project, barring special
circumstances (City of Scottsdale n.d.). As of November 2010, "over 8,000 native plant
permits have been issued, amounting to an estimated 350,000 protected plants
salvaged since the implementation of the ordinance (Planning and Development
Services, City of Scottsdale 2010, 3).
Larimer County, Colorado, recognizing the importance of wildlife in their region,
adopted wildlife protection regulations that require developments of less than two
acres to minimize adverse impacts to areas defined as important wildlife habitat.
Minimum requirements include a setback of at least 100 feet between development and
wildlife habitat areas, native vegetation only, minimal disturbance to existing natural
vegetation, wildlife-proof trash receptacles, wildlife-friendly fencing, control of
domestic animals, and exterior lighting (SCOTie n.d.).
Erosion and Soil Health
Soil testing programs can assist property owners in properly amending their
soils. Some jurisdictions require soil testing. In the State of Californias Model Water
Efficient Landscape Ordinance (MWELO), a soil sample must be submitted for analysis
(State of California 2015). Others encourage it, such as the City of Seattle, where the
King Conservation District provides has a program that provides free soil nutrient
testing to residents (City of Seattle Department of Planning and Development 2010).
Composting in urban areas has been met with some challenges, with some
considering composting to be a "nuisance. Cities such as Chicago allow composting
while using nuisance control provisions or development standards to ensure that
composting does not become a public health risk (Mukherji and Morales 2010, 6).
Comprehensive Land Use Code Update
While many of the aforementioned case studies highlight emerging practices
regarding a single ecosystem benefit, few cases exist in which the majority (or all) of the
landscape-related ecosystem services are addressed. However, the City of Indianapolis,
Indiana recently adopted a major overhaul to its zoning code to take effect on April 1,
2016. Titled "Indy Rezone, the ordinance revision process "starts with the premise that
the built environment impacts a wide variety of issues and behaviors. Currently, the
development regulations and zoning ordinances that govern Indianapolis yield a result
that the community, in general, is unsatisfied with and the city can no longer sustain
(City of Indianapolis, Indiana n.d.). Fourteen separate ordinances were rewritten into a
single ordinance with five parts in order to make the code more sustainable and more
livable (City of Indianapolis, Indiana n.d.). Code changes relating to landscaping include
Impervious pavement: eliminates parking requirements on small lots (under
5000 sq. ft.); establishes maximums and if maximums are exceeded, requires use
of pervious materials;
Stormwater Runoff: Strengthens the provisions needed to mitigate flood impacts
when development occurs in an area that is regularly flooded; mitigation
provisions include required offsets and water storage; Requires LID techniques
be used in new subdivisions (commercial, residential, industrial); coordination
of stormwater management features with landscaping features through the use
of the Green Factor scoring tool.
Trees: Requires frontage trees on private land for new development;
incentivizes the preservation of trees via the Green Factor scoring system;
establishes a preferred tree species list as well as a prohibited list; requires
preservation of Heritage trees (big, native trees).
Urban Agriculture: Allows community gardens in nearly all districts as well as
personal livestock with single family detached homes; establishes safe protocols
for community gardens, and addresses personal livestock (City of Indianapolis,
Notably, Indianapolis acknowledges the importance of landscaping in addressing
multiple objectives. The use of The Green Factor, a system that scores the site design for
achieving multiple objectives, "changes landscaping requirements from simply
placement vegetation on a site to a more integrated functional landscape (City of
Indianapolis, Indiana n.d.).
Unfortunately, the rewritten section of the landscaping code is still weak or
silent on some strategies that would benefit ecosystems. First, the code only requires
60% vegetative cover in landscaping (more progressive codes require 100% coverage).
While the section encourages drought-tolerant plans ("shall), prohibits invasive
species ("shall not), it merely allows and does not explicitly encourage the selection of
native species ("permitted). It also does not make mention of plants suited to
pollinators and wildlife habitat, and fencing requirements do not take into account
RESULTS: HOLISTIC GUIDELINES FOR ECOSYSTEM SERVICE LANDSCAPE TREATMENTS
This paper researched landscape treatments commonly used in human
settlements that can promote food production, soil health, microclimate, social relations
and cultural identity, stormwater and water quality management, water availability,
wildfire hazard reduction, air quality, wildlife and pollinators, and carbon
sequestration. This information has been compiled into a set of guidelines, listed per
treatment, that local governments can utilize when evaluating and updating their land
use codes and developing programs that encourage ecosystem-friendly landscaping on
their residential, commercial, and public property.
Developing a plant database or pointing to a reputable existing list of acceptable
or prohibited plant species is vital to the implementation of the regulations or
programs. As an example in the guidelines below, additional guidance regarding these
landscaping considerations have been inserted for the Colorado Front Range region of
the United States. Similar resources should be sought out in the geographical region in
which these recommendations are to be used, and such resources should consider
characteristics such as plasticity to ensure the greatest opportunity for resilience while
encouraging the greatest opportunity for plant diversity (Hunter 2011).
Turf grass should be minimized on site and be used only for areas of heavy
pedestrian traffic and physical recreation, as it requires heavy water, fertilizer, and
pesticide use. Shade trees should be planted in conjunction with turf grass to moderate
the levels of water evaporation from turf grass.
Native grasses can offer an alternative to turf grass, as they are more tolerant to
the local climate, are often more drought tolerant, and therefore require less water.
Landscape ordinances should not restrict the use of native grasses. A native plants list
should be made available to the public for details on geographically appropriate
grasses. For the Colorado Front Range, see the Colorado State University Extensions
Fact Sheet on Native Grasses For Use In Colorado Landscapes (Schonle 2009).
Mowing equipment should be electrically powered to reduce air pollution and
greenhouse gas emissions. Lawn clippings should remain on the grass to promote soil
health and moisture conservation.
The covenants or declarations, bylaws, and rules and regulations of common
interest communities should not require ground-covering vegetation to consist of a
minimum percentage of turf grass.
If in a high wildfire hazard zone, turf grass may be used in the 30-foot defensible
space perimeter around a home, and should be mowed regularly and to a short height.
Native grasses may be used outside of the 30-foot defensible space perimeter around a
home, and should be a maximum height of eight inches (Dennis 2012).
Flowering vegetation such as milkweed should be planted that provides nectar
for critical pollinators such as honeybees and monarch butterflies, as well as other
wildlife (National Wildlife Federation n.d.). Milkweed should be avoided in areas with
livestock. A variety of flowering plants should be planted with varied timing of nectar
flow, extending the season as far as possible (Hunter 2011). Native flowers are
encouraged and invasive species are prohibited. Consult Ecoregional Planting Guides
put forth by the Pollinator Partnership for details on species and geographically
appropriate flowering vegetation (Pollinator Partnership n.d.).
Native species should be selected for landscapes to the greatest extent possible.
A native plants list should be made available to the public for details on species-and
geographically-appropriate plants. For the Colorado Front Range, see the Colorado
Native Plant Societys list of Suggested Native Plants for Gardening and Landscape Use
on the Front Range of Colorado (Colorado Native Plant Society 2008).
Drought-tolerant and fire-resistant species should be selected for land located in
drought or wildfire-prone areas, or areas that may become drought or wildfire-prone in
the future due to climate change. Consult the Firewise Landscaping and Plant List for
details on geographically appropriate plants (Firewise Communities n.d.). For the
Colorado Front Range, see Colorado State University Extensions FireWise Plant
Materials Fact Sheet (Dennis 2012).
Plants should be selected for their plasticity, or how well they perform in a range
of conditions in order to prepare for changing temperatures as a result of climate
change. This can be achieved by selecting plants that have the greatest plant hardiness
zone range (Hunter 2011). Consult the United States Department of Agricultures Plant
Hardiness Zone Map as well as the American Horticultural Societys Plant Heat Zone
Map to determine the ranges within which plant varietals will thrive (United States
Department of Agriculture n.d.) (American Horticultural Society n.d.).
Plants selected for their rough leaf surfaces and trees planted in groups or rows
can most effectively filter dust and remove particles from the air.
The covenants or declarations, bylaws, and rules and regulations of common
interest communities should not prohibit or limit xeriscape or drought-tolerant
vegetation. Common interest communities can, however, adopt and enforce design or
aesthetic guidelines that require the installation of drought-tolerant vegetative
landscapes and regulate the type, number, and placement of drought-tolerant plantings
that an owner may install.
Botanic gardens and public institutions who possess plants for educational,
scientific, historic or collection purposes and take precautions to prevent non-native
species from going to seed or spreading beyond the existing planting may be exempt
from these recommendations (The New York City Council 2013).
Landscape ordinances should be amended to clarify that native plant and
flowering plant species are not considered to be weeds (Sample Amending Ordinance
Native shrubs that provide food and habitat to wildlife should be planted in
landscapes. A native plants list should be made available to the public for details on
species-and geographically-appropriate shrubs. For the Colorado Front Range, consult
Colorado State University Extensions Fact Sheet on Native Shrubs for Colorado
Landscapes (Klett, Fahey and Cox 2008).
Variation in species promotes biodiversity. Therefore, no one species of shrub
should make up more than 30% of the total number of shrubs in the landscape (City of
Indianapolis, Indiana n.d.).
For new developments, a minimum of X trees per X feet should be required.
Native tree species are encouraged and invasive species should be prohibited. Trees
(specifically deciduous trees for cold climates) should be planted against the wall of a
home to reduce interior heating and cooling costs. A native plants list should be made
available to the public for details on species-and geographically-appropriate trees. For
the Colorado Front Range, consult Colorado State University Extensions Fact Sheet on
Native Trees for Colorado Landscapes (Klett, Fahey and Cox 2008).
Where possible, fruit trees tolerant to the climate should be planted if the
property owners or the community at large can harvest the fruit.
Variation in species promotes biodiversity. No one species of tree should make
up more than 30% of the total number of trees in the landscape (City of Indianapolis,
If in a high wildfire hazard zone, trees should be planted 30 feet between
clusters of two to three trees, or 20 feet between individual trees. Deciduous trees are
more fire-resistant than conifer trees, and are therefore preferred. If conifer trees are
selected for use, they should possess a thick bark, long needles, and be self-pruning. All
trees should be pruned up six to ten feet off the ground, and should not overhang a
Fencing is encouraged as an aesthetic screen between disparate uses. In critical
wildlife habitat areas, fencing should be a maximum of four feet tall, and the type of
fencing allowed must be appropriate to the species of wildlife, to be determined by the
authorized wildlife authority. Wildlife-friendly fencing is typically highly visible to
mammals and birds, allows wildlife to jump over or crawl under, and provides wildlife
access to important habitats and travel corridors. For the Colorado Front Range, see the
Colorado Parks and Wildlife publication "Fencing with Wildlife in Mind (Hanophy
Water Retention and Detention Features
A bird bath, puddling area, pond, or rain garden is encouraged to promote
wildlife. Water features should use recycled water. Integration of Stormwater Best
Management Practices (BMPs) should be required for new development and
encouraged for existing development. Water features may be suspended during periods
of drought if deemed a burden on water resources.
Impervious and Partially Pervious Areas
Rockscaping should be discouraged. Impervious pavement should occupy as
little as possible, and no more than X% of the total area of the property. Pervious
pavement strategy such as gravel, pervious interlocking concrete pavers, or concrete
should be substituted for impervious asphalt and cement. If in a high wildfire hazard
zone, paved driveways and gravel walkways can be strategically positioned as "fuel
Plant vegetation in appropriate water zones, and tailor irrigation to water zone
needs. Employ drip irrigation and low-volume spray or bubbler systems.
Organic mulch should cover the soil under plants and all non-vegetated areas of
the landscape. If in a high wildfire hazard zone, mulch should be encouraged to
conserve moisture. Pine bark, thick layers of pine needles, or other mulches that readily
carry fire should be prohibited. Vegetable gardens should be exempted from mulching
Fruit and Vegetable-Bearing Plants
Vegetable gardens consisting of fruit and vegetable-bearing plants should be
permitted and encouraged in residential areas, and encouraged in commercial and
industrial areas with a permit. A soil sample should be required in commercial and
industrial areas and encouraged in residential areas prior to planting in order to
determine that the existing soil is free of harmful contaminants and doesnt require any
additional treatment. Vegetable planter boxes used with purchased soil should be
encouraged as an alternative to ground beds on contaminated land and do not require a
A residential property owner adjacent to a vacant lot should be able to apply to
plant a vegetable garden or community garden on the adjacent vacant lot. Greenhouses
for the growth of vegetables should be permitted in residential areas and allowable in
commercial and industrial areas with a permit.
Pesticide and Fertilizer Use
Use of fertilizers containing phosphorus or other compound containing
phosphorus (such as phosphate) should be prohibited. Application of fertilizers should
be prohibited during a formally established "restricted season (rainy season).
Application of fertilizers should be prohibited in designated fertilizer-free zones, on
impervious, frozen, or saturated surfaces, and within 15 feet of water bodies.
Application of fertilizer should be restricted in designated "low maintenance zones
(Dane County, Wisconsin 2011).
Exceptions in which phosphorus-based fertilizer may be used could include
curing a lack of phosphorus in the soil as determined by a soil analysis, establishing new
turf grass, or repairing turf grass. Golf courses, sod farms, and agricultural uses may be
exempted from the prohibition of phosphorus-based fertilizers (Dane County,
Preserving Existing Vegetation
For new construction or substantial renovation that includes modification to the
landscape, protected native plants should not be destroyed, mutilated, or removed
from, or relocated on the premises except in accordance with an approved native plant
program required in conjunction with the issuance of a native plant permit (City of
Scottsdale, Arizona n.d.) Removal of any historic tree should be prohibited unless
specific criteria are met (City of Indianapolis 2015).
Benefits and Drawbacks of Landscape Treatment by Ecosystem Service
When viewed holistically and summarized in table form, it is easier to see which
landscape treatments offer the greatest number of benefits to ecosystem services. See
Table 3 below for a ranking of "valuable, "can be valuable, "can be problematic,
"problematic and not applicable ("n/a) for each landscape treatments contribution to
the ecosystem services examined in this paper. While an examination of the full table
may yield the richest information, assigning a numerical value to each ranking (2 points
for "valuable, 1 point for "can be valuable, 0 points and removal from denominator for
"n/a, -1 point for "can be problematic, and -2 points for "problematic) also
demonstrates which treatments can yield the most benefit across multiple services and
which may pose the greatest harm.
Table 2: Ranking of Landscape Treatment by Ecosystem Service
LOCAL REGIONAL GLOBAL
Landscape Element Food Erosion & Soil Health Microclimate Cultural Services Stormwater Management Water Quality Water Avail. Wildfire Reduction Air Quality Pollinators & Wildlife Carbon Sequestration Score
Mulch CBV V V N/A N/A V V CBV V V N/A 1.75
Flowering vegetation V V V V V V CBV CBP V V V 1.64
Non-flowering vegetation N/A V V V V V CBV CBP V V V 1.60
Shrubs N/A V V N/A V V CBV CBP V V V 1.56
Native grasses N/A V V V V V CBV CBP V CBV V 1.50
Irrigation V V V N/A N/A N/A CBP V V N/A N/A 1.50
Trees CBV V V V V V CBP CBP V V V 1.36
Water features N/A CBV V V CBV CBV P V N/A V N/A 1.13
Fruit and vegetable- bearing plants V CBV V V V CBP P CBP V V V 1.00
Turf grass N/A CBP V V V CBV P CBV P CBP P 0.00
Pesticides & fertilizers CBV P N/A V N/A P N/A N/A N/A P N/A -0.60
Fencing CBV N/A N/A CBP N/A N/A N/A N/A N/A P N/A -0.67
Impervious & partially pervious areas N/A P P N/A P P N/A V CBP P P -1.38
Based on this calculation, the treatments ranked in the following order from
highest to lowest score for all eleven ecosystem services: mulch (1.75), flowering
vegetation (1.64), non-flowering vegetation (1.60), shrubs (1.56), native grasses (1.50),
and irrigation (1.5), trees (1.36), water features (1.13), fruit and vegetable-bearing
plants (1.00), turf grass (0.00), pesticides and fertilizers (-.60), fencing (-.67), and
impervious and partially pervious areas (-1.38). This information may enable local
governments to promote multifunctionality when designing landscapes, while paying
special attention to particular landscape treatments that provide the greatest value or
are most problematic to ecosystem services.
As numerous studies have pointed out (Intergovernmental Panel on Climate
Change 2013) (Intergovernmental Platform on Biodiversity and Ecosystem Services
2015) (Millennium Ecosystem Assessment 2005) (TEEB The Economics of Ecosystems
and Biodiversity 2011), anthropogenic changes to the earths climate and air, water,
and land quality and availability have caused distress and decline in ecosystems
globally. Because humans rely on the many services that ecosystems provide, it is
valuable to investigate opportunities for preserving and regenerating ecosystems.
While the preservation of large swaths of land must be pursued, local governments of
the worlds human settlements -whether densely populated cities or small rural towns
- can enact policies and programs that seek to enhance, rather than hinder, the services
that natural ecosystems provide. This approach can elevate land associated with
residential, commercial, or public property to an ecological "highest and best use
alongside the intended economic use of the propertys structures.
Such holistic thinking can promote landscape uses and treatments that are meet
multiple needs, promote regenerative rather than linear systems, and optimize the
relationship with natural processes. This paper has identified ecosystem services that
can be generated or enhanced through the selection of appropriate landscape
treatments on land in urban, suburban, and rural areas. By compiling scientific
literature and case studies, a set of guidelines for landscape treatments that view the
promotion of ecosystem services in a comprehensive way was put forth in this paper.
Analysis of the landscape treatment options by ecosystem benefit yielded information
about which treatments served the greatest functions across services, and which were
the most detrimental. Case studies that highlighted approaches that other
municipalities, counties, and states have taken to support ecosystem services at the site
level provide a jumping off point to local governments regarding regulatory, fee-based,
and voluntary programs that can achieve ecosystem benefits.
Every landscape recommendation cannot be implemented by a single program
or ordinance. Local governments can make great strides in incorporating these
recommendations throughout their codes, permitting processes, regulatory fees, and
incentive programs by assessing all processes together for their effects on ecosystems.
This sentiment is supported by experts who point out that tree protection must be
achieved through a community forest management strategy, rather than a tree
ordinance alone (Swiecki and Bernhardt 2001); and water quality must be achieved
through assessment of regulations and procedures across departments (U.S.
Environmental Protection Agency 2009). Experts from numerous related fields should
be called upon during the development of local regulations or programs in order to
achieve true multifunctionality. Landscape architects, planners, and ecologists could be
brought together to conduct "designed experiments that test concepts and ensure a
balance between ecological, aesthetic, and urban functional goals is met (Hunter 2011).
If these strategies are pursued, local governments can participate in the
protection of ecosystems in their communities, thereby contributing to the global effort
needed to ensure that the human species can continue to receive critical life-sustaining
services from natures ecosystems.
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