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Seed dispersal and stand structure in southwestern white pine (pinus strobiformis engelmann)

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Title:
Seed dispersal and stand structure in southwestern white pine (pinus strobiformis engelmann)
Creator:
Riser, James P
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English
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63 leaves : ; 28 cm

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Subjects / Keywords:
Southwestern white pine -- Seeds ( lcsh )
Southwestern white pine -- Ecology ( lcsh )
Seeds -- Dispersal ( lcsh )
Animal-plant relationships ( lcsh )
Corvidae ( lcsh )
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bibliography ( marcgt )
theses ( marcgt )
non-fiction ( marcgt )

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Bibliography:
Includes bibliographical references (leaves 50-59).
General Note:
Department of Integrative Biology
Statement of Responsibility:
by James O. Riser.

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|University of Colorado Denver
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|Auraria Library
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All applicable rights reserved by the source institution and holding location.
Resource Identifier:
53887022 ( OCLC )
ocm53887022
Classification:
LD1190.L45 2003m R57 ( lcc )

Full Text
SEED DISPERSAL AND STAND STRUCTURE
IN SOUTHWESTERN WHITE PINE
(PINUS STROBIFORMIS ENGELMANN)
by
James P. Riser II
B.S., Northern Arizona University, 1995
A thesis submitted to the
University of Colorado at Denver
in partial fulfillment
of the requirements for the degree of
Master of Arts
Biology
2003


!
This thesis for the Master of Arts
degree by
James P. Riser II
has been approved by
Leo P. Bruederle


Riser II, James P. (M.A., Department of Biology)
Seed Dispersal and Stand Structure in Southwestern White Pine (Pinus strobiformis
Engelmann)
Thesis directed by Associate Professor Leo P. Bruederle
ABSTRACT
Southwestern white pine (Pinus strobiformis Engelmann, Pinaceae) has been
reported to have its seeds dispersed by the Clark's nutcracker (Nucifraga Columbiana,
Corvidae) where the two species are sympatric in the northern portion of the pines
range. Clark's nutcrackers store widely dispersed caches of pine seeds in the ground
for subsequent use. Forgotten or unutilized seeds are able to germinate, often
forming a tree cluster comprised of more than one genotype. Ecological pressures
and damage may also cause individual trees to resemble tree clusters, but in these
cases, the trunks are of one genotype, and are referred to as multi-trunked trees. In
this thesis research, I examined the impact of Clarks nutcracker on southwestern
white pine stand structure. Populations of southwestern white pine inside and outside
of the Clark's nutcracker's (the presumed major seed disperser) range were surveyed
for stand structure and the presence of tree clumps. Allozyme analysis was used to
distinguish multi-trunked individuals from tree clusters, and thereby test for evidence
of vertebrate seed dispersal. Forest structure differed considerably among the four
forests sampled, although southwestern white pine was co-dominant in each.
m


Structure of the southwestern white pine stands also differed considerably; however,
all four were variously all-aged stands. Variation at seven polymorphic loci revealed
multi-genet clusters throughout the sampled range of southwestern white pine, with
25 of the 35 tree clumps sampled comprising clusters of genetically different
individuals. Relatedness of individuals within clusters ranged from -1.0619 (highly
unrelated) to 0.8133 (highly related). Average relatedness within the range of Clarks
nutcracker was 0.0561 (0.5429), while outside of the birds range relatedness
averaged 0.5974 (0.2086). While there were fewer clusters encountered outside of
the nutcrackers range; the experimental design (e.g., few sites) makes comparisons
difficult. Overall low levels of relatedness differ from that reported in previous
studies. Differences between sites and the impact of other seed-caching vertebrates
confound interpretations. While I found evidence of vertebrate seed dispersal in
southwestern white pine, the role of rodents and other corvids needs to be more
closely examined.
This abstract accurately represents the content of the candidates thesis. I recommend
its publication.
Signed
Leo P. Bruederle
IV


DEDICATION
I dedicate this thesis to my parents, Jim and Joyce Riser, for all of their love and
support for my research, and throughout my life.


ACKNOWLEDGEMENT
My thanks to my advisor, Dr. Leo P. Bruederle, for his guidance throughout this
project, instruction in the laboratory and helping with field collecting.
Dr. John Hubbard provided valuable help regarding Clarks nutcracker locations and
distributions. Ian McCune assisted with the Relatedness calculations and provided
direction in the laboratory. Kathy Honda and the inter library loan staff at the Auraria
Campus Library provided invaluable assistance in tracking down hard to find
references. Carolyne Janssen at the Auraria Media Center provided technical
assistance with Figure 1.1. Special thanks go to the following for taking time out of
their busy schedules to help with field collecting: Jorge Alzaga, Peter Brown, George
Ferguson, Sarah Gallup, Jim Riser, and Ros Wu. I would also like to thank the San
Juan National Forest and the Coronado National Forest for allowing me to conduct
this research on their land.


CONTENTS
Figures.........................................................................ix
Tables...........................................................................x
Chapter
1. Introduction..................................................................1
1.1 Other seed dispersers........................................................7
1.2 Hypotheses..................................................................8
2. Taxonomic history...........................................................10
3. Methodology.................................................................13
3.1 Study Sites................................................................13
3.1.2 Stand Characterization Transects.........................................15
3.2. Extraction............................................................... 16
3.2.2 Electrophoresis..........................................................16
3.3 Statistical Analysis........................................................18
3.3.1 Forest Structure..........................................................18
3.3.2 Genetic Relatedness.......................................................18
4. Results.....................................................................20
4.1 Forest Structure...........................................................20
4.2 Southwestern White Pine Stand Structure....................................27
vii


4.3 Southwestern White Pine Population Genetic Structure....................33
4.3.1 Genotypes..............................................................33
4.3.2 Allozyme Analysis of Tree Clumps.......................................33
4.3.3 Relatedness Analyses...................................................36
5. Discussion................................................................39
References...................................................................50
Appendix
1. Tree species encountered in the stand characterization transects in each of four
Pinus strobiformis Engelmann (Pinaceae) study sites in Arizona and Colorado..60
2. Electrophoretic phenotypes for ten allozyme loci examined in Pinus strobiformis
Engelmann (Pinaceae) at four study sites in Arizona and Colorado.............61
3. Relatedness values for all Pinus strobiformis Engelmann (Pinaceae) clumps
sampled at four study sites in Arizona and Colorado..........................63
viii


FIGURES
Figure
1.1 Location of Pinus strobiformis Engelmann (Pinaceae) study sites relative to the
distribution of southwestern white pine, P. flexilis James, and Clarks nutcracker in
the southwestern USA..............................................................6
4.1 Density of southwestern white pines (Pinus strobiformis Engelmann, Pinaceae)
across three growth classes (seedlings < 1.5 m tall; saplings > 1.5 m tall, but < 9 cm
dbh; trees > 9 cm dbh) at four southwestern white pine sites in Colorado and Arizona
28
4.2 Distribution of southwestern white pine {Pinus strobiformis Engelmann,
Pinaceae) trees by diameter, in 5 cm diameter classes, at four southwestern white pine
sites in Colorado and Arizona....................................................29
4.3 Diagram of AAT-2, ACPH, IDH, SDH-1, and PGD-2 electrophoretic phenotypes
observed from southwestern white pine {Pinus strobiformis Engelmann, Pinaceae) at
four sites in Colorado and Arizona...............................................34
4.4 Diagram of PER-1 and PER-2 electrophoretic phenotypes observed from
southwestern white pine {Pinus strobiformis Engelmann, Pinaceae) at four sites in
Colorado and Arizona.............................................................35
ix


TABLES
Table
3.1 Land ownership, elevation, aspect, general slope, and area for four Pinus
strobiformis Engelmann (Pinaceae) study sites in Arizona and Colorado..........14
4.1 Total trees encountered, basal area, absolute density, relative density, absolute
dominance, relative dominance, and importance value for all tree species at the
Williams Creek site in the San Juan Mountains of Colorado.....................21
4.2 Total trees encountered, basal area, absolute density, relative density, absolute
dominance, relative dominance, and importance value for all tree species at the Wolf
Creek Pass site in the San Juan Mountains of Colorado..........................23
4.3 Total trees encountered, basal area, absolute density, relative density, absolute
dominance, relative dominance, and importance value for all tree species at the Onion
Saddle site in the Chiricahua Mountains of Arizona.............................24
4.4 Total trees encountered, basal area, absolute density, relative density, absolute
dominance, relative dominance, and importance value for all tree species at the
Madera Canyon site in the Santa Rita Mountains of Arizona......................26
4.5 Total trees, absolute density and absolute dominance for each of four Pinus
strobiformis Engelmann (Pinaceae) stands in Colorado and Arizona..............31
4.6 Tree sites, number of seedlings, number of clumps by growth class, and frequency
of clumps in Pinus strobiformis Engelmann (Pinaceae) at four study sites in Colorado
and Arizona....................................................................32
4.7 Range and average relatedness (r) among individual trees comprising clusters at
four Pinus strobiformis Engelmann (Pinaceae) sites, within the range of Clarks
nutcracker in Colorado, outside of the range of Clarks nutcracker in Arizona, and
overall........................................................................37
I
X


1. Introduction
A plants population genetic structure, and therefore its evolutionary potential,
can be influenced by life history traits (e.g., Hamrick and Godt 1989, 1997). Seed
dispersal, in particular, can impact the evolutionary potential of a species as
determined by the amount of genetic variation and manner in which that variation is
organized (e.g., Hamrick et al. 1979; Levin 1981; Loveless and Hamrick 1984;
Hamrick et al. 1991; Hamrick et al. 1992; Hamrick et al. 1993).
Pine (Pinus L.) seeds are an important food source for many forest animals.
Furthermore, interactions among seed predators and pines have important impacts on
the ecology and evolution of pines (e.g. Elliott 1974; Smith and Baida 1979; Tombaclc
1983; Vander Wall 1992a, 1992b; Benkman 1995; Martinez-Delgado et al. 1996;
Coffey et al. 1999) While caching seeds for subsequent use, many of these seed
predators inadvertently fill the role of seed disperser for the pines (e.g. Tomback 1982;
Hayashida 1989; Vander Wall 1992a, 1992b, 1994; Hutchins et al. 1996). One group
of pines in particular, the white pines (subgenus Strobus), has responded evolutionary
to take advantage of these seed predators and their caching behavior (e.g., Vander
Wall and Baida 1977, 1981; Baida 1980; Lanner 1980; Tomback and Linhart 1990;
Tomback et al. 1990).
Several species of white pines rely on seed caching members of the Corvidae
1


for seed dissemination. The interaction of the Clarks nutcracker (Nucifraga
columbiana), a member of the corvid family, and several white pine species is well-
documented (Vander Wall and Baida 1977, 1981; Tomback 1978, 1981, 1982, 2001;
Lanner and Vander Wall 1980; Hutchins and Lanner 1982; Lanner 1980, 1996;
Tomback and Linhart 1990; Tomback et al. 1990). The significance of these
associations may be illustrated by the Clark's Nutcracker-limber pine (P.flexilis
James) mutualism (Lanner 1980; Lanner and Vander Wall 1980; Benkman et al. 1984;
Tomback and Linhart 1990). In this system, limber pine has evolved a suite of
characters (presumably due to selective pressures exerted by the nutcracker, in part) to
facilitate bird dispersal (Lanner 1980, 1998). These characters include sessile cones,
upswept branches, and large wingless seeds. Winged seeds are dispersed by wind, the
usual and presumably ancestral condition in pines (Lanner 1980; Critchfield 1986).
The evolution of these characters is driven by the nutcrackers pine seed harvesting
and caching behavior.
The nutcracker has evolved a sublingual pouch for seed storage and transport,
in addition to well-developed spatial memory skills for relocating buried seed caches
(Tomback 1980, 2001; Vander Wall and Baida 1981; Vander Wall 1982). Still, some
seed caches are not utilized. As a result of unutilized caches and a preference for open
cache sites, the nutcracker inadvertently plants pine seeds in new areas. The birds
preferentially select areas that have steep slopes and are free of vegetation, with
~>


exposed mineral soil ideal conditions for seedling establishment (Lanner and Vander
Wall 1980; Vander Wall and Baida 1981; Tomback 1986; Tomback and Linhart
1990). Often, this coincides with a recent forest fire or other disturbance (Tomback et
al. 2001). Additionally, by caching several seeds at a site and often using the same
general location for multiple caches (e.g., hillside), the Clarks nutcracker can effect
the colonization of new areas by these pines (Tomback 1990).
Wind-dispersed pines typically exhibit a population structure characterized by
decreasing genetic relatedness with increasing distance from the seed source (Linhart
et al. 1981; Knowles 1984). Vertebrate, especially avian, seed dispersal may alter this
family structure (although short dispersal distances characteristic of rodents may
not). The caching activities of Clarks nutcracker have been shown to influence the
population genetic structure of several species of white pines (e.g., Carsey and
Tomback 1994; Tomback and Schuster 1994; Bruederle et al. 2001). The nutcracker
buries from one to 30 seeds at each cache location (Tomback 1998; Vander Wall and
Baida 1981). if more than one of these seeds germinates, they can result in a cluster
of trees within which stems may fuse as they increase in diameter (Linhart and
Tomback 1985; Weaver and Jacobs 1990; Carsey and Tomback 1994; Tomback and
Schuster 1994). Tomback et al. (1990) and Carsey and Tomback (1994) standardized
the use of the terms clump and cluster to differentiate between multi-trunked trees
of undetermined genetic structure (clump) and multi-trunked trees comprising more
3


than one genet (cluster). Trees composed of a single genotype with several stems are
simply referred to as multi-trunked trees.
The tree-cluster growth form of bird-dispersed pines reveals a strong family
structure spatial patterning of related individuals (Fumier et al. 1987) within a
cluster, while comparisons with surrounding stems show little family structure (Fumier
et al. 1987; Rogers et al. 1999). Because the seeds of any one pouchload are often
collected from the same tree (or even the same cone), there is a high probability that
the seeds comprising a cache are related as half- or full-siblings, sharing a maternal
parent (Tomback 1988, 1998; Carsey and Tomback 1994). In fact, Carsey and
Tomback (1994) showed that, on average, stems within clusters of limber pine were
related as slightly less than full-sibs. Caching activity of the Clarks nutcracker can
thus lead to strong genetic structuring at the fine-scale level involving tree clusters,
while contributing to randomization of the populations genetic variation on larger
scales across a population and across a landscape (Rogers et al. 1999). Multiple
trunks in pines can be due to other causes, such as porcupine damage, insect damage
(e.g., Chamberlin and Aarssen 1996), unstable soil, death of the terminal leader
(Schuster and Mitton 1991), and polyembryony (e.g., Krutovskii and Politov 1995).
Alternatively, it may also occur spontaneously, with no obvious cause (Dvorak et al.
2000). Using genetic tools (e.g., allozymes) one can elucidate whether a clump is
composed of one individual or several, genetically distinct individuals (Linhart and
4


Tomback 1985; Carsey and Tomback 1994).
While the relationship of corvids and some white pines is well studied, the
interaction between vertebrate seed dispersers and southwestern white pine (Pinus
strobiformis Engelmann) is not. First described in 1848 by Engelmann, P.
strobiformis has been a source of taxonomic confusion ever since. Additionally, the
northern limit of southwestern white pine has been in dispute, much of it related to
whether one treats the trees as P. strobiformis or a variety of P.flexilis James. In
Flora of North America, Krai (1993) considered the northern portion of southwestern
white pines range as P. flexilis, but this is in contrast to Critchfield and Little (1966),
local floras (e.g., Weber 1987; Douglas 1992; Komarek 1994; Michener-Foote and
Hogan 1999), and the authors experience (J. Riser pers. obs.)
Southwestern white pine is distributed throughout the southwestern United
States and northern Mexico (Fig. 1.1, see also Critchfield and Little 1966).
Throughout most of its distribution in the southern Basin and Range province of
western North America, southwestern white pine is found in somewhat isolated stands
or forests occupying the middle and upper altitudes of characteristically discontinuous
mountain ranges separated by dry desert valleys (Critchfield and Little 1966; Little
1971; Farjon and Styles 1997; J. Riser pers. obs.).
Southwestern white pines large, wingless seeds imply that vertebrate seed
dispersal is important to this tree. However, only the northern portion of its
5


Figure 1.1. Location of Pinus strobiformis Engelmann (Pinaceae) study sites ()
relative to the distribution of southwestern white pine (red), P.flexilis James (green),
and Clarks nutcracker (blue) in the southwestern USA. Modified from Critchfield
and Little (1966) and Tomback (1998).
6


distribution is sympatric with Clarks nutcracker. Therefore, other seed dispersers,
such as some rodents and other corvid species, must be important in dispersing
southwestern white pines seeds in the majority of its range.
1.1 Other Seed Dispersers
The range of Clarks nutcracker overlaps several other corvids [e.g., Stellers
jay (Cyanocitta stelleri), scrub jay (Aphelocoma coerulescens), Mexican jay
{Aphelocoma ultramarina), and pinon jay (Gymnorhinus cyanocephalus)] that are
known to cache pine seeds (Benkman et al. 1984; Vander Wall and Baida 1981). The
ranges of several of these corvids extend considerably further south than that of the
Clarks nutcracker (National Geographic Society 1987). Several rodents, such as red
squirrels (Tamiasciurus hudsonicus), ground squirrels (Spermophilus sp.), grey
squirrels (Sciurus sp.), chipmunks (Eutamias sp.), and deer mice (Peromyscus
maniculatus) are also sympatric with southwestern white pine (Hall and Kelson 1959)
and utilize pine seeds (e.g., Finley 1969; Smith 1970; Martinez-Delgado et al. 1996;
Samano and Tomback 2003). These rodents are also known to cache pine seeds
(Benkman et al. 1984; Vander Wall 1992a, 1992b, 1993, 1994, 1997).
These other corvids and mammals are sympatric with, and utilize, southwestern
white pine in much of the southern portion of its range (Samano and Tomback 2003).
While Stellers jays will remove seeds from cones (e.g., Samano and Tomback 2003),
many of these other seed predators (e.g., mice and chipmunks) are more precisely
7


secondary seed dispersers, as they horde seeds that have already fallen to the ground
via wind dispersal from cones (Vander Wall 1992a). Seed caching by secondary seed
dispersers could result in some multi-genet tree clusters occurring outside of the range
of Clarks nutcracker. While squirrels will remove and cache entire cones in their
middens (Finley 1969; Samano and Tomback 2003), they also will collect individual
seeds and cache these in small, dispersed caches, as well. These cone middens are
unsuitable for seedling establishment due to factors such as a lack of mineral soil,
excessive moisture, and low sunlight availability (Finley 1969; Hutchins and Lanner
1982; Samano and Tomback 2003). However, the small, dispersed caches are suitable
for seed germination if the rodents do not consume the seeds (e.g., Vander Wall
1992b, 1994).
1.2 Hypotheses
Because large portions of southwestern white pines range fall outside that of
Clarks nutcrackers (Tomback 1998; Fig. 1), three hypotheses are proposed. First,
populations of P. strobiformis are dispersed (primarily and secondarily) by vertebrates
throughout the range of this pine, as predicted by its wingless seed morphology.
Whereas Lanner (1980, 1996, 1998) and Tomback (1998) have postulated the use of
P. strobiformis seeds by Clarks nutcrackers, Benkman et al. (1984) and Samano and
Tomback (2003) have documented this from the San Francisco Peaks in northern
Arizona and at W'illiams Creek in the San Juan Mountains in southern Colorado,
8


respectively. Lanner (1980) reported the formation of clumps in southwestern white
pine and McCune (2001) demonstrated the occurrence of clusters at one location in
central New Mexico. Assuming Clarks nutcrackers are the main seed dispersers, it is
expected that southwestern white pine tree clumps will occur at a higher density within
the range of Clarks nutcrackers, than outside. This also assumes that other multi-
trunked tree causal agents (e.g., porcupines, erosion, or even other vertebrate seed
cachers) are equally prevalent across the range of southwestern white pine. The third
hypothesis suggests that fewer of the tree clumps encountered outside of the
nutcrackers range will be multi-genet clusters. Sampling stands from both inside and
outside of the nutcrackers range allows for comparison of the impact and degree to
which avian seed dispersal, specifically by Clarks nutcrackers, has on population
genetic structure and stand structure in southwestern white pine.
9


2. Taxonomic History
George Engelmann (1848) first described P. strobiformis Engelmann from
material collected in northern Chihuahua, Mexico. He never mentioned this taxon
again in his later works (Engelmann 1878; 1882), but named samples from just
northwest of Chihuahua, in Arizona, as varieties of Pinus flexilis James (all these
varieties have been synonymized under P. flexilis var. reflcxa Engelmann or P. reflexa
Engelmann which, in turn, is often synonymized under P. strobiformis).
Foreshadowing future confusion, Parry and Engelmann (1862) described P. flexilis
growing near Santa Fe, NM, with characters that would now be considered indicative
of P. strobiformis. In 1909, Shaw reduced P. strobiformis to a variety of Mexican
white pine: P. ayacahuite Ehrenberg ex Schlechtendal var. brachyptera Shaw.
Unfortunately, this name has frequently been used incorrectly in conjunction with P.
strobiformis, for which it is a synonym (e.g., Lanner 1980; Perry 1991). Also treating
southwestern white pine as a variety of Mexican white pine, Lemmon (1895) published
the name P. ayacahuite Ehrenberg ex Schlechtendal var. strobiformis (Engelmann)
Lemmon, an invalid combination (he should have used P. ayacahuite var.
brachyptera) that was also used by Price et al. (1998) for southwestern white pine.
However, the latter also mentioned that southwestern white pine probably deserves
recognition at the species level as P. strobiformis. Andresen and Steinhoff(1971)
10


reviewed the taxonomy of P. strobiformis but, in this authors opinion, their account is
plagued by inaccuracies and errors; furthermore, their morphometric study (SteinhofF
and Andresen 1971) suffered from extremely low sample numbers and incomplete
samples in the critical areas of sympatry. Farjon and Styles (1997) recognized both P.
strobiformis and P.flexilis var. reflexa in their treatment of Mexican pines, and
provided a useful discussion of the taxonomy and proliferation of names pertaining to
these taxa.
This nomenclatural history has led to considerable confusion regarding the
taxonomy of southwestern white pine as it is currently recognized in the northern
portions of its range. Is it P. strobiformis, P. reflexa, a variety of P.flexilis, or some
combination of these? Additionally, the northern limit of southwestern white pine has
been in dispute, much of it related to whether one treats the trees as P. strobiformis or
a variety of P.flexilis. Little (1971) in his Atlas of United States Trees and Krai
(1993) in Flora of North America, considered the northern portion of southwestern
white pines range as P.flexilis, but this is in contrast to Critchfield and Little (1966),
local floras (e.g., Weber 1987; Douglas 1992; Komarek 1994; Michener-Foote and
Hogan 1999), and the authors experience (J. Riser pers. obs.) The taxonomic status
of southwestern white pine is further confused by its variable morphology and close
resemblance to limber pine in one to several traits, including growth form. A seemingly
useful character for discriminating limber pine from southwestern white pine is the
11


presence of a well-defined, and often tall trunk in the latter (e.g., Weber 1987).
However, on environmentally stressful sites, southwestern white pine may exhibit a
stunted and much branched habit that can make it difficult to differentiate from limber
pine (J. Riser pers. obs.).
12


3. Methodology
3.1 Study Sites
I identified four southwestern white pine study sites from the southwestern
United States (Tab. 3.1; Fig. 1.1)- two inside the year-round or reliable range of the
Clarks nutcracker and two outside this range. I used ornithological records and
observations (Willard 1916, Marshall 1957; Phillips et al. 1964; Westcott 1964;
Fischer 1994; Tomback 1998; Dr. John Hubbard, pers. comm.) to help determine the
two sites outside the nutcrackers range.
Site 1 was located along a slope beside the Williams Creek trail above
Williams Creek Reservoir in the San Juan Mountains of Colorado. Site 2 was located
adjacent to the Wolf Creek Pass overlook, along Colorado Highway 160, also in the
San Juan Mountains. Site 3 was located in Madera Canyon, near the Old Baldy Trail
on the slopes of Mt. Wrightson in the Santa Rita Mountains of southern Arizona. Site
4 was located near Onion Saddle in the Chiricahua Mountains in southern Arizona.
The San Juan and Coronado National Forests issued sampling permits for this work.
13


Table 3.1. Land ownership, elevation, aspect, general slope, and area for four Pinus
strobiformis Engelmann (Pinaceae) study sites in Arizona and Colorado.____________
Study Site Land ownership Elevation Aspect Slope Area
Williams Creek San Juan N. F., Pagosa Ranger District, CO 2658 m 136 34 0.250 ha
Wolf Creek Pass San Juan N. F., Pagosa Ranger District, CO 2670 m 191 21 0.528 ha
Onion Saddle Coronado N. F., Douglas Ranger District, AZ 2377 m 104 18 0.315 ha
Madera Canyon Coronado N. F., Nogales Ranger District, AZ 2256 m 004 34 0.074 ha
I collected needle tissue from an exhaustive sample of approximately 100
individual stems at each site to capture the genetic and structural diversity of the
southwestern white pine stands. Previous studies have shown that a large sample (>
50) is needed in order to resolve relationships when tree clumps are uncommon
(McCune 2001). To obtain the appropriate sample number, the area of the plot varied
with local tree densities.
I recorded individual stems, whether in clumps or not, as seedlings, saplings or
trees. Seedlings were any tree less than 1.5 m tall; saplings equaled or exceeded 1.5
m, but were less than 9 cm diameter at breast height (dbh); and trees equaled or
exceeded 9cm dbh. Diameter at breast height of stems over 9.0 cm diameter (trees) or
diameter at root collar on stems less than 9.0 dbh and/or under 1.5 m tall (seedlings
and saplings) was recorded for each tree species, as well. Single trunked trees and
clumps were treated as tree sites and numbered. Stems within clumps were
14


designated with letters (e.g, a, b, c, etc.) Each stems precise location within the plot
was recorded on an x-y grid using measuring tapes. I sampled individual stems from
all single- and multi-trunked southwestern white pine tree sites found within the plot to
determine whether clumps were multi-genet clusters or multi-ramet individuals. A
sample consisting of two to five branch tips (10-50 fascicles) was collected from each
individual stem. Newly germinated seedlings were recorded but, to prevent damaging
them, they were not sampled. I placed samples into numbered plastic sandwich bags,
which were kept cool in an ice-filled cooler for transport back to the Plant Systematics
Lab at the University of Colorado at Denver.
3.1.2 Stand Characterization Transects
Three belt transects five m wide and 50 m long were surveyed at each study
site to characterize forest structure and determine the relative density of southwestern
white pine clumps in these stands. I established transects adjacent to the study sites,
about five meters apart, except at Wolf Creek Pass and Onion Saddle where, due to
the small size of the southwestern white pine stands, the transects were superimposed
on the plots described in the previous section. Diameter at breast height for all trees,
or diameter at root collar for all seedlings and saplings was recorded for all tree
species. I tallied all southwestern white pines as individual trees or tree clumps.
Needle tissue was collected for genetic analysis from all southwestern white pine
clumps within the transects in order to supplement the samples collected for genetic
15


analysis in the aforementioned plots.
3.2 Extraction
I extracted soluble enzymatic proteins in a 0.16 M phosphate buffer solution,
pH 7.0 (0.093 g germanium oxide, 0.3 g diethyldithiocarbamic acid, 4.4 g
polyvinylpyrrolidone [molecular weight 40,000], 1.21g sodium metaborate, 0.33 g
sodium metabisulfite, 4.4 g ascorbic acid [sodium salt], 8.8 ml dimethyl sulfoxide, 0.6
ml 2-phenoxyethanol, and 0.18 ml P-mercaptoethanol [modified from Mitton et al.
1979]). Needle samples were ground to a powder under liquid nitrogen with a mortar
and pestle. As the liquid nitrogen evaporated off, I added the extraction buffer to
make a slurry (Mitton et al. 1979). Enzymes were then absorbed into filter paper
wicks (Whatmans Chromotography Paper 17 Chr) of approximately 14 mm x 3 mm
placed into the slurry mixture. Wicks were stored at -70 C until electrophoresis.
3.2.2 Electrophoresis
Four gel-electrode buffer systems were used to resolve ten genetic loci
previously demonstrated to be polymorphic for southwestern white pine (McCune
2001): sodium-borate pH 7.5/7.6, lithium-borate pH 8.1/8.5, tris-citrate pH 6.7/6.3,
and morpholine-citrate pH 6.1 (Poulik 1957; Selander et al. 1971; Cheliak and Pitel
1984; Conkle et al. 1982; Rogers et al. 1999; McCune 2001.) The sodium-borate
system was run at a constant current of 45 mA until the voltage reached 300 V, at
which point the power supply was adjusted to produce a constant voltage (300V) for
16


the remaining nine hours. The remaining three systems were run at constant current:
the lithium-borate system for approximately eight hours at 50 mA, the tris-citrate
system at 60 mA for ten hours, and the morpholine-citrate system for ten hours at 55
mA. Substrate specific histochemical staining was used to resolve enzymes in four
combinations sodium-borate: aspartate aminotransferase (AAT), peroxidase (PER),
phosphoglucomutase (PGM), shikimate dehydrogenase (SDH); lithium-borate:
aspartate aminotransferase (AAT), glutamate dehydrogenase (GDH),
phosphoglucomutase (PGM), triosephophate isomerase (TPI); tris-citrate:
glyceraldehyde-3-phosphate (G3PDH), malate dehydrogenase (MDH); morpholine-
citrate: acid phosphatase (ACPH), isocitrate dehydrogenase (IDH), malate
dehydrogenase (MDH), and 6-phosphogluconate dehydrogenase (PGD) (Bruederle et
al. 1998; McCune 2001).
I scored allozyme data as individual genotypes for each putative locus. The
most rapidly migrating allele at a locus was designated a, with more slowly
migrating alleles labeled b, c... etc. Isozymes were numbered with the fastest
migrating isozyme locus being 1, the next fastest 2, and so on.
17


3.3 Statistical Analyses
3.3.1 Forest Structure
Absolute density and absolute dominance were calculated for each seedling,
sapling, and tree species based upon the aforementioned transect data and are reported
as stems/ha and m2/ha, respectively. Relative density and relative dominance, reported
as percentages, were then recalculated for each species based upon their relative
contribution to a size class, e.g., seedling. Finally, I calculated an importance value for
all species in each class by summing the relative density and relative dominance and
halving this value for a maximum value of 100.
The southwestern white pine stands were further described by calculating
relative densities from the plot data separately for seedling, sapling, and tree classes.
Additionally, the tree class was further subdivided into the following diameter classes
based upon dbh: 9.0-14.9 cm. 15.0-19.9, 20.0-24.9, 25.0-29.9, and >30.0. These data
represented detailed stand structure for each study site.
3.3.2 Genetic Relatedness
Relatedness 5.0 (Goodnight 2002) was used to evaluate relatedness (r) among
individuals within each multi-stemmed tree site for all ten loci. Relatedness was
determined as follows:
r = IxLkI,(Py-P*)/IxIkX,(Px-P*);
18


where Py is the frequency of the allele in locus k for individual y, Px is the frequency of
the allele in locus k for individual x, and P* is the frequency of the allele in the
population (Queller and Goodnight 1989). Relatedness was calculated as an average
of all loci for all individuals within each tree cluster. Loci were considered
polymorphic if there was at least one alternate allele present, regardless of frequency.
Clumps were considered multi-genet if the individuals comprising them varied at one
or more loci.
19


4. Results
The results of this study are organized in the following manner: forest structure
of the stands; southwestern white pine stand structure, specifically; and, genetic
analysis of southwestern white pine clumps.
4.1 Forest Structure
The transect data revealed the four sites to differ considerably, both with
respect to species composition and forest structure. Typically, southwestern white
pine was co-dominant in the canopy with several other species. However, importance
values varied for each tree species and for each growth class (Appendix 1; Tables 4.1-
4).
Of the six tree species at Williams Creek, four occupied the canopy, which
was dominated by white fir [Abies concolor (Gord. & Glend.) Hildebr]. Although
white fir, southwestern white pine, and Douglas-fir [Pseudotsuga menziesii (Mirb.)
Franco] exhibited similar densities (Table 4.1); the white firs were significantly larger
resulting in an importance value of 43.2, in comparison to 29.1 and 23.7 for
southwestern white pine and Douglas-fir, respectively. While there was an increased
diversity in the sapling class, Douglas-fir, southwestern white pine, and white fir were
co-dominant, having similar importance values (33.2, 29.1, and 28.7, respectively).
With an importance value of 34.7, southwestern white pine dominated the seedling
20


Table 4.1. Total trees encountered, basal area, absolute density, relative density, absolute dominance, relative
dominance, and importance value for all tree species at the William's Creek site in the San Juan Mountains of
Colorado.
Total Basal Area Absolute Relative Absolute Relative Importance
Trees (m2)1 Density2 Density3 (%) Dominance4 Dominance5 (%) Value6
Trees
Abies concolor 17 1111 68.0 33.3 444.2 53.1 43.2
Pinus strobiformis 17 52.0 68.0 33.3 207.8 24.8 29.1
Pseudotsuga menziesii 15 37.6 60.0 29.4 150.2 17.9 23.7
Pinus ponderosa 2 8.7 8.0 3.9 34.9 4.2 4.0
51 209.3 204.0 100.0 837.1 100.0 100.0
Saplings
Pseudotsuga menziesii 20 4.1 80.0 35.7 16.4 30.6 33.2
Pinus strobiformis 17 3.7 68.0 30.4 14.9 27.8 29.1
Abies concolor 14 4.3 56.0 25.0 17.3 32.3 28.7
Pinus ponderosa 2 1.0 8.0 3.6 3.9 7.3 5.4
Picea engelmannii 2 0.2 8.0 3.6 1.0 1.8 2.7
Populus tremuloides 1 <0.1 4.0 1.8 0.1 0.2 1.0
56 13.4 224.0 100.0 53.6 100.0 100.0
Seedlings
Pinus strobiformis 24 0.3 96.0 42.9 1.1 26.5 34.7
Pinus ponderosa 6 0.3 24.0 10.7 1.3 32.5 21.6
Pseudotsuga menziesii 10 0.2 40.0 17.9 1.0 23.7 20.8
Abies concolor 12 0.2 48.0 21.4 0.6 15.3 18.4
Populus tremuloides 4 <0.1 16.0 7.1 0.1 2.0 4.6
56 1.0 224.0 100.0 4.1 100.0 100.0
I yi I I III. Ml. Mil l| I .1^
(/2 diameter) x n, n/ha, absolute density/total density x 100, m /ha, absolute dominance/total dominance x 100,
6 calculated as: (relative density + relative dominance)/2


class due to its high relative density. However, ponderosa pine (Pinus ponderosa
Dougl. ex Laws.), Douglas-fir, and white fir seedlings were important components of
the seedling class, as well, with importance values of 21.6, 20.8, and 18.4,
respectively.
White fir dominated the canopy at Wolf Creek Pass, with an importance value
of 40.1, due to a high density of relatively small trees (Table 4.2). Southwestern white
pine and Douglas-fir had the second and third highest importance values, 28.9 and
28.6, respectively, due to a lower density of larger trees. White fir also dominated the
sapling and seedling classes. A high density of white fir saplings resulted in an
importance value of 72.0, almost seven times greater than aspen (Populus tremuloides
Michx.) and southwestern white pine. Douglas-fir was second in importance to white
fir in the seedling class, these two species having importance values of 28.1 and 67.1,
respectively. Southwestern white pine exhibited little reproduction at this site, being
poorly represented in the seedling class.
Of the nine species represented in the canopy at the Onion Saddle site, silver
leaf oak ( Q. hypoluecoides A. Camus), southwestern white pine, and Douglas-fir were
co-dominant, with importance values of 28.9, 21.6, and 18.5, respectively (Table 4.3).
Whereas silver leaf oak was represented by a high density of relatively smaller trees,
southwestern white pine and Douglas-fir were represented by larger trees, occurring at
relatively lower densities. Due to their larger sizes, southwestern white pine and
22


Table 4.2. Total trees encountered, basal area, absolute density, relative density, absolute dominance, relative
dominance, and importance value for all tree species at the Wolf Creek Pass site in the San Juan Mountains of
Colorado.
Total Trees Basal Area (m2)1 Absolute Density2 Relative Density3 (%) Absolute Dominance4 Relative Dominance5 (%) Importance Value6
Trees
Abies concolor 45 103.8 85.2 54.2 196.5 26.0 40.1
Pinus strobiformis 13 168.0 24.6 15.7 318.1 42.0 28.9
Pseudotsuga menziesii 22 122.9 41.7 26.5 232.7 30.8 28.6
Populus tremuloides 3 4.9 5.7 3.6 9.3 1.2 2.4
Saplings 83 399.5 157.2 100.0 756.6 100.0 100.0
Abies concolor 37 7.2 70.1 69.8 13.6 74.2 72.0
Populus tremuloides 8 0.9 15.2 15.1 1.6 8.8 11.9
Pinus strobiformis 6 0.9 11.4 11.3 1.7 9.5 10.4
Pseudotsuga menziesii 2 0.7 3.8 3.8 1.4 7.5 5.7
Seedlings 53 9.7 100.4 100.0 18.4 100.0 100.0
Abies concolor 14 0.3 26.5 63.6 0.5 70.6 67.1
Pseudotsuga menziesii 6 0.1 11.4 27.3 0.2 29.0 28.1
Populus tremuloides 1 <0.1 1.9 4.5 <0.1 0.3 2.4
Pinus strobiformis 1 <0.1 1.9 4.5 <0.1 0.1 2.3
22 0.4 41.7 100.0 0.7 100.0 100.0
1 ('A diameter)2 x n,2 n/ha,3 absolute density/total density * 100,4 nr2/ha, * absolute dominance/total dominance X 100,
6 calculated as: (relative density + relative dominance)/2


Table 4.3. Total trees encountered, basal area, absolute density, relative density, absolute dominance, relative
dominance, and importance value for all tree species at the Onion Saddle site in the Chiricahua Mountains of Arizona.
Total Absolute Relative Absolute Relative Importance
Trees Basal Area Density Density (%) Dominance Dominance (%) Value
Trees
Quercus hypoleucoides 36 74.6 114.3 40.9 236.8 16.9 28.9
Pinus strobiformis 20 90.0 63.5 22.7 285.8 20.4 21.6
Pseudotsuga menziesii 14 92.6 44.4 15.9 294.1 21.0 18.5
Pinus engelmannii 3 70.8 9.5 3.4 224.8 16.1 9.7
Pinus arizonica 4 44.9 12.7 4.5 142.6 10.2 7.4
Quercus arizonica 6 25.4 19.0 6.8 80.7 5.8 6.3
Juniperus deppeana 1 32.1 3.2 1.1 101.8 7.3 4.2
Pinus discolor 3 4.6 9.5 3.4 14.6 1.0 2.2
Quercus gambelii 1 5.9 3.2 1.1 18.9 1.3 1.2
88 441.0 279.4 100.0 1400.1 100.0 100.0
Saplings
Pinus discolor 53 4.7 168.3 54.1 15.0 35.0 44.5
Pseudotsuga menziesii 23 4.6 73.0 23.5 14.7 34.3 28.9
Quercus hypoleucoides 15 2.5 47.6 15.3 8.0 18.6 17.0
Pinus strobiformis 6 1.1 19.0 6.1 3.6 8.4 7.3
Quercus arizonica 1 0.5 3.2 1.0 1.6 3.7 2.4
98 13.5 311.1 100.0 43.0 100.0 100.0
Seedlings
Pinus strobiformis 4 0.1 12.7 4.5 0.2 89.3 46.9
Pinus discolor 66 <0.1 209.5 75.0 <0.1 9.7 42.4
Pseudotsuga menziesii 10 <0.1 31.7 11.4 <0.1 0.7 6.0
Juniperus deppeana 5 <0.1 15.9 5.7 <0.1 0.1 2.9
Quercus gambelii 2 <0.1 6.3 2.3 <0.1 <0.1 1.1
Pinus engelmannii 1 <0.1 3.2 1.1 <0.1 0.1 0.6
88 0.1 279.4 100.0 0.2 100.0 100.0


Douglas-fir had the largest absolute dominance values. 285.8 and 294.1, respectively.
However, silver leaf oaks higher density gave it the largest importance value at the
site. Border pinon (Pinus discolor D. K. Bailey & Hawksw.) was poorly represented
in the canopy, but dominated the sapling class with an importance value of 44.5. This
species was second in importance in the seedling class, following southwestern white
pine. Douglas fir and silver leaf oak were also important in the sapling class with
importance values of 28.9 and 17.0, respectively. Although southwestern white pine
was not an important component of the sapling class, it was co-dominant with border
pinon in the seedling class due to a low density of large seedlings; importance values
for these two species were 46.9 and 42.4, respectively.
At Madera Canyon, four of the six tree species encountered occurred in the
canopy. Southwestern white pine dominated all three size classes, with importance
values of 53.6, 70.4, and 46.7 for trees, saplings, and seedlings, respectively (Table
4.4). While Arizona pine (Pinus arizonica Engelm.) was second in importance in the
tree and sapling classes, with values of 26.0 and 29.5, respectively, it did not appear in
the seedling class. Gambel oak (Quercus gambelii Nutt.) had an importance value of
14.9 in the tree class, but was absent from both the sapling and seedling classes.
Neither alligator juniper (Juniperus deppeana Steud.) nor net leaf oak (Quercus
rugosa Nee) were present in the tree and sapling classes, but were both well
represented as seedlings, with importance values of 33.2 and 11.8, respectively.
25


Table 4.4. Total trees encountered, basal area, absolute density, relative density, absolute dominance, relative
dominance, and importance value for all tree species at the Madera Canyon site in the Santa Rita Mountains of
Arizona.
Total Trees Basal Area (m2)1 Absolute Density2 Relative Density1 (%) Absolute Dominance4 Relative Dominance5 (%) Importance Value6
Trees
Pinus strobiformis 31 177.2 418.9 58.5 2394.4 48.7 53.6
Pinus arizonica 14 92.9 189.2 26.4 1255.6 25.6 26.0
Quercus gambelii 4 81.0 54.1 7.5 1094.2 22.3 14.9
Quercus hypoleucoides 4 12.6 54.1 7.5 169.8 3.5 5.5
Saplings 53 363.6 716.2 100.0 4914.0 100.0 100.0
Pinus strobiformis 33 6.8 445.9 78.6 92.6 62.3 70.4
Pinus arizonica 9 4.1 121.6 21.4 55.9 37.6 29.5
Seedlings 42 11.0 567.6 100.0 148.5 100.0 100.0
Pinus strobiformis 51 0.3 689.2 62.2 4.1 31.3 46.7
Juniperus deppeana 1 0.6 13.5 1.2 8.6 65.2 33.2
Quercus rugosa 18 <0.1 243.2 22.0 0.2 1.6 11.8
Quercus hypoleucoides 12 <0.1 162.2 14.6 0.3 1.9 8.3
82 1.0 1108.1 100.0 13.2 100.0 100.0
1 (V2 diameter)2 x it,2 n/ha,3 absolute density/total density x 100,4 m2/ha,5 absolute dominance/total dominance x 100,
6 calculated as: (relative density + relative dominance)/2


4.2 Southwestern White Pine Stand Structure
Southwestern white pine stand structure varied considerably among sites (Fig.
4.1). All four stands were more or less all-aged. This indicates that recruitment has
been somewhat continuous, but at varying levels at each site. Trees dominated the
Onion Saddle site (58.5%), while the majority of southwestern white pine occurred as
seedlings at Madera Canyon (59.6%) and Williams Creek (49.5%). Wolf Creek Pass
had a more even distribution of seedlings (31.1%) and saplings (22.6%), with a
somewhat higher frequency of trees (46.2%), closely approximating an all-aged forest.
With respect to the 20.8% of individuals representing the tree class at
Williams Creek, most were distributed somewhat evenly in the three smallest diameter
classes, 28.6%, 23.8%, and 33.3%, respectively. The two largest classes comprised
only 9.5% and 4.8% of the trees. At Wolf Creek Pass. 46.2% of the individuals were
in the canopy, of which most were either in the smallest diameter class, 42.9%, or the
largest, 34.7%. At the Onion Saddle site, there was a decreasing frequency of trees
with increasing diameter. However, the smallest diameter class was the largest,
comprising 32.4% of the trees. Of the 18.2% of individuals representing the tree class
at Madera Canyon, 55.0% were in the smallest diameter class (Figs. 4.1, 4.2).
While each of these stands may be described as all-aged, reproduction by
southwestern white pine varied considerably from site to site. Williams Creek and
27


William's Creek
0.6
0.4
w
c
Q 0.2
0.4950
0.2970'
0.2079
Seedlings
Saplings
Growth class
Trees
0.8
0.6
c
CD
Q
Onion Saddle
0.5847
0.0847 1 1 0.3305 P_ _J
Seedlings
Saplings
Growth class
Trees
Wolf Creek Pass
Growth class
Madera Canyon
Growth class
Figure 4.1. Density of southwestern white pines (Pinus strobiformis Engelmann, Pinaceae) across three growth classes
(seedlings < 1.5 m tall; saplings >1.5 m tall, but < 9 cm dbh; trees >9 cm dbh) at four southwestern white pine sites in
Colorado and Arizona.


to
SO
William's Creek
Diameter classes (cm)
Onion Saddle
Diameter classes (cm)
Wolf Creek Pass
Madera Canyon
Diameter classes (cm)
Figure 4.2. Distribution of southwestern white pine (Pinus strobiformis Engelmann, Pinaceae) trees by diameter, in 5
cm diameter classes, at four southwestern white pine sites in Colorado and Arizona.


Madera Canyon exhibited high to extremely high levels of reproduction, as reflected
by seedling densities of 196.0 and 878.4 seedlings per hectare, respectively (Table
4.5). In contrast, Wolf Creek Pass and Onion Saddle had much lower levels of
southwestern white pine recruitment, with seedling densities of 62.5 and 31.7 per
hectare, respectively. Recruitment, and therefore regeneration, of southwestern white
pine was not directly correlated with importance (density and dominance) in the
canopy. Whereas Madera Canyon, which had the highest density and dominance of
southwestern white pine, also exhibited the greatest reproduction; Williams Creek had
the lowest density and dominance for southwestern white pine, but the second greatest
amount of regeneration. While Onion Saddle had the second highest density and
dominance of trees, it had the lowest density of seedlings, indicating poor
reproduction. Wolf Creek Pass had the lowest seedling density overall. (Table 4.5)
The frequency of clumps also varied among study sites, with Williams Creek
having the highest frequency 23.8% of all tree sites comprised clumps. In contrast,
Madera Canyon, Wolf Creek Pass, and Onion Saddle had considerably fewer clumps,
which occurred at similar frequencies, 4.5%, 4.7% and 3.4% of tree sites, respectively
(Table 4.6). The mean number of stems per clump across all four study sites,
including the transects, was 2.3 ( 0.50). Of the 38 clumps encountered, the majority
(30 clumps, 78.9%) comprised two stems, seven clumps (18.4%) comprised three
stems, and one clump (2.6%), at Wolf Creek Pass, comprised four stems
30


Table 4.5. Total trees, absolute density and absolute dominance for each of four Pinus
strobiformis Engelmann (Pinaceae) stands in Colorado and Arizona.
Study Site Total Trees (n) Absolute Density1 Absolute Dominance"
Williams Creek, CO
Trees 20 80.0 279.9
Saplings 29 116.0 18.6
Seedlings 49 196.0 4.2
Wolf Creek Pass, CO
Trees 49 92.8 763.8
Saplings 24 45.5 16.1
Seedlings 33 62.5 0.6
Onion Saddle, AZ
Trees 68 215.9 876.3
Saplings 40 127.0 29.0
Seedlings 10 31.7 0.8
Madera Canyon. AZ
Trees 19 256.8 1088.5
Saplings 25 337.8 81.3
Seedlings 65 878.4 6.7
, T "
n/ha, m"/ha
31


Table 4.6. Tree sites, number of seedlings, number of clumps by growth class, and frequency of clumps in Pinus
strobiformis Engelmann (Pinaceae) at four study sites in Colorado and Arizona.__________________________________
Study Site Number Number of Number of clumps Total clumps1 Frequency
of tree sites seedlings Seedlings Saplings Trees Mixed2 of clumps
Williams Creek 101 50 10 9 4 1 (sa/tr) 24 23.8 %
Wolf Creek Pass 106 33 2 1 1 1 (sa/tr) 5 4.7 %
Onion Saddle 118 10 0 0 3 1 (sa/tr) 4 3.4%
Madera Canyon 110 65 1 1 1 1 (sa/tr) 1 (se/sa) 5 4.5 %
138 clumps were encountered, of which 35 were sampled for genetic analyses (see text).
2 Mixed clumps were composed of either saplings and trees (sa/tr) or seedlings and saplings (se/sa).


4.3 Southwestern White Pine Population Genetic Structure
4.3.1 Genotypes
Of the ten loci examined, seven were polymorphic: AAT-2, ACPH, IDH,
PGD-2, PER-1, PER-2, and SDH-1 (Appendix 2). AAT-2, IDH, and PGD-2, were
resolved as dimers, with no more than two alleles at a locus. ACPH and SDH-1 were
resolved as monomers, with two and three alleles per locus, respectively (Fig. 4.3).
PER-1 and PER-2 were also resolved as monomers, but harbored four alleles each and
exhibited a complicated banding pattern often involving overlapping bands (Fig. 4.4).
Three loci were monomorphic: AAT-1, MDH-2, and PGM-1.
4.3.2 Allozyme Analysis of Tree Clumps
Of the 35 clumps sampled across the sites (including those clumps encountered
in the transects), allozyme analysis revealed that 25 (71.4%) were clusters of
genetically different individuals. At the Williams Creek site, 17 of the 21 clumps
sampled (80.9%) were revealed to be clusters. (Two clumps found at the Williams
Creek site were not sampled one was too small to safely remove tissue without
harming the individuals, while the lowest branches of the second were out of reach.
Additionally, one clump failed to resolve on any of the gel systems.) Of the five
clumps encountered at both Wolf Creek Pass and Madera Canyon, four (80%) were
33


1 III
bb ab ac cc
ACPH AAT-2

II 1 1
ab bb be ab bb
SDH-1 IDH
aa ab
PGD-2
Figure 4.3. Diagram of AAT-2, ACPH, IDH, SDH-1, and PGD-2 electrophoretic
phenotypes observed from southwestern white pine (Pinus strobiformis Engelmann,
Pinaceae) at four sites in Colorado and Arizona. AAT-2, IDH, and PGD-2, were
resolved as dimers, with no more than two alleles at a locus. ACPH and SDH-1 were
resolved as monomers, with two and three alleles per locus, respectively.
34


Figure 4.4 Diagram of PER-1 and PER-2 electrophoretic phenotypes observed from
southwestern white pine (Pinus strobiformis Engelmann, Pinaceae) at four sites in
Colorado and Arizona. PER-1 and PER-2 were resolved as monomers, but harbored
four alleles and exhibited a complicated banding pattern often involving overlapping
bands.
35


multi-genet clusters. In contrast, only one (25%) of the four clumps at Onion Saddle
was revealed to be multi-genet.
4.3.3 Relatedness Analyses
Relatedness values among individuals comprising the clumps sampled ranged
from 1.0000 to -1.0619 (Appendix 3). Values of 1.0000 may reflect trees that are
genetically identical or those indistinguishable based upon this sample of ten allozyme
loci; smaller values indicate decreasing relationship. I treated these stems as being
genetically indistinct ramets or multi-trunked trees for the purpose of this study, and
omitted them from the following calculations.
Overall relatedness among individual stems within tree clusters varied from
-1.0619 to 0.8133, averaging 0.1602 ( 0.5386) across the four sampled southwestern
white pine sites (Table 4.7). Average relatedness for the two northern stands within
the Clarks nutcrackers range was 0.0561 ( 0.5429), while the average relatedness of
clusters outside the nutcracker's range was 0.5974 ( 0.2086).
Average relatedness at the Williams Creek site was low (0.1359 0.5557),
with one of the 17 clusters being highly unrelated (-1.0619). The Wolf Creek Pass site
had an average relatedness of -0.2829 ( 0.3592), indicating very low relatedness
among stems within the four clusters. The Onion Saddle site had only one cluster, for
which there was a very high degree of relatedness among stems (0.7711). The four
36


Table 4.7. Range and average relatedness (/) among individual trees comprising clusters at four Pinus strobiformis
Engelmann (Pinaceae) sites, within the range of Clarks nutcracker in Colorado, outside of the range of Clarks
nutcracker in Arizona, and overall._____________________________
Study Site Range of r Mean r
Williams Creek -1.0619-0.7397 0.1359 ( 0.5557) (n = 17 )
Wolf Creek Pass -0.7039 0.0677 -0.2829 ( 0.3592) (n = 4)
Onion Saddle - 0.77111 (n=l)
Madera Canyon 0.3615-0.8133 0.5539 ( 0.2132) (n = 4)

>
J
\
>
J
Clarks
Nutcrackers
range
inside
outside
Range
of r
-1.0619
0.7397
0.3615-
0.8133
Mean r
Overall Overall
Range of r Mean r
0.0561
( 0.5429)
(n= 21)
V -1.0619
/ 0.8133
0.1602
( 0.5386)
(n = 26)
0.5974
( 0.2086)
(n = 5)
1 One cluster was encountered at Onion Saddle; therefore, no mean or standard deviation is available.


clusters encountered in the Madera Canyon transects had an average relatedness of
0.5539 ( 0.2132), indicating that individuals comprising the clusters were also highly
related, at the level of full-sibs.
38


5. Discussion
While detailed studies of the relationship between corvids and pines have been
undertaken for numerous white pine species (Pinus subgenus Strobus), at least 13
white pines have characteristics of vertebrate seed dispersal for which the nature of
this relationship is either uncertain or anecdotal (see Bruederle et al. 2001, Table 1).
Southwestern white pine exhibits the large wingless seeds of bird-dispersed pines.
However, the majority of its distribution falls outside the range of the Clarks
nutcracker, a species implicated in the seed dispersal of many bird-dispersed pines in
North America north of Mexico.
Multi-genet clusters were found at each of four study sites, representing a
sample through a significant portion of the range of P. strobiformis in North America,
north of Mexico (Figure 1.1). Even stands outside of the Clarks nutcrackers reliable
range had some tree clusters derived, presumably, from seed caches. Although
caching and multi-genet clusters have previously been documented in southwestern
white pine (Samano and Tomback 2003; McCune 2001), this study expands on this
earlier work and represents the first published report of this phenomenon across a
significant portion of the species range.
While a greater disparity with respect to clump frequency was expected,
southern sites did exhibit fewer clumps, on average (Tab. 4.6). Williams Creek and
39


Onion Saddle exhibited the highest and lowest number of clumps, respectively.
However, Wolf Creek Pass and Madera Canyon had similar frequencies, only slightly
higher than that at Onion Saddle. Whereas I expected a higher frequency of multi-
genet clusters within the range of Clarks nutcracker, this was not strictly the case.
Williams Creek and Wolf Creek Pass had similar frequencies (clusters relative to
clumps), 80.9% and 80.0%, respectively. However, Madera Canyon had essentially
the same frequency of clusters when compared to the two sites within the nutcrackers
range (80.0%). Only Onion Saddle differed, with 25% of the clumps being resolved as
clusters.
Age structure provides insight into the colonization history and successional
status of a stand. While southwestern white pine stands might be expected to be even-
aged due to the manner in which colonization occurs following a forest disturbance, all
four stands were variously all-aged. Furthermore, all four of the stands were
comprised of predominantly young trees, with only Wolf Creek Pass having a large
proportion of large, and presumably older, trees. However, it is important to reiterate
that the study sites varied considerably among each other, with respect to both forest
and stand structure, thereby making generalizations difficult (Appendix 1; Figs. 4.1,
4.2). It is doubtful that my growth classes reflect disturbance histories the use of
only three classes obscures much of the size/age variation between individuals.
The Williams Creek stand of southwestern white pine is a relatively young
40


forest that is still in the early stages of colonization. The site is relatively open, south-
southeast facing, with few shrubs an ideal site in which Clarks nutcrackers were
recently documented caching seeds (Samano and Tomback 2003). Not surprisingly,
this site had the highest frequency of clumps, most of which were composed of
seedlings and saplings. Of these clumps, 80.9% were clusters.
The Wolf Creek Pass site was dominated by white fir and Douglas-fir both
shade tolerant, late-successional species with an admixture of southwestern white
pine. The southwestern white pine stand was essentially all-aged with a
preponderance of relatively large trees. However, recruitment into the site by
southwestern white pine was relatively low, with succession progressing to a white
fir/Douglas-fir dominated mixed-conifer forest. Even though the site faces nearly
south, it may no longer be attractive for caching by Clarks nutcrackers due to the high
density of white fir and Douglas-fir. Only five clumps where found here, two
comprised of seedlings, one of saplings, and one sapling-tree combination. The
majority of these were multi-genet clusters.
The Onion Saddle site was the most speciose of the sites, with southwestern
white pine being second in importance. Over half of the southwestern white pines
encountered were trees; these were distributed across the diameter classes, but skewed
toward the smallest size class. The low number of seedlings, low density of clumps,
advanced age of the clumps (five of the six clumps were composed solely of trees),
41


and low frequency of clusters at this site suggests that colonization by southwestern
white pine took place in the recent past, probably less than fifty years ago. It also
appears not to have been initiated by Clarks nutcrackers. Other corvids (e.g.,
Stellers jay) present in the Chiricahua Mountains may be responsible for transporting
southwestern white pine seed to this site. Current low seedling densities indicate that
the stand is not replacing itself.
Southwestern white pine seedlings and saplings, as well as trees, dominated
the Madera Canyon site. However, the majority of individuals were seedlings and, of
the trees, over half were in the smallest diameter class. This extremely young stand is
regenerating vigorously at this site. However, Clarks nutcracker is unlikely the agent
of seed dispersal. I recorded only five clumps, of which one was comprised of
seedlings, three comprised saplings, and one comprised a sapling-tree combination.
However, other vertebrate seed dispersers with differing caching behaviors (e.g.,
rodents) may be important at this site.
Several sources of error may cause over- or under-estimates of the actual
number of clusters derived from vertebrate seed caches at each site. Competition
between cache-mates could result in only one individual surviving to reproduce. This
would cause me to underestimate the number of clusters found at the sites. However,
these data do not indicate this, as I encountered clusters in all growth classes (albeit at
varying frequencies) indicating low competition between seedlings. With competition
42


between cache-mates one would expect to find many clusters in the seedling growth
class, fewer clusters in the sapling class, and very few in the tree growth class. In fact,
several clusters were comprised of individuals from more than one growth class.
Allozyme analysis provides a minimum estimate of the genetic differences
present in each clump. These seven polymorphic loci represent only a small portion of
the potential genetic diversity present in any individuals genome and it is expected
that allozyme analysis will fail to resolve some clumps as clusters. Of the 35 clumps
sampled from the plots and transects (two clumps encountered were not sampled and
one sampled clump tailed to resolve on any of the buffer systems), nine were
unresolved as clusters based upon allozyme analysis. Of these, four were distinct
groups of seedlings clearly arising from multi-seeded caches. One of the five clumps
encountered at Madera Canyon was composed of two spatially distinct, albeit
genetically indistinguishable, seedlings, revealing an unresolved cluster. Similarly,
each of two clumps from Williams Creek and one from Wolf Creek Pass were
composed of two separate seedlings, indicating they are unresolved clusters. The one
clump from Williams Creek that was not resolved on any of the buffer systems (low
enzymatic activity precluded inclusion in the genetic analysis ) was composed of three
distinct seedlings suggesting that it, too, was a cluster. Observations reveal that the
genetic data underestimate the actual number of clusters and that there may be more
clusters at the sites than was revealed by the genetic analysis.
43


The presence of two or more seedlings arising from a common point is
suggestive of caching by nutcrackers (or other vertebrates), but may also be explained
by polyembryony-the formation of more than one embryo per seed. Due to multiple
fertilization events and/or subsequent cleavage of the resulting embryos, several
embryos may be initiated by a single megagametophyte (Krutovskii and Politov 1995).
Clusters formed by polyembryony may be indistinguishable from those derived from
Clarks nutcracker caches (especially in the case of polyzygotic polyembryony).
However, competition between embryos typically results in only one embryo per
megagametophyte surviving to germinate, making polyembryony somewhat rare,
occurring at a frequency of <1-3% (Mirov 1967, Ledig 1998, Krutovskii and Politov
1995). At the Williams Creek site, for example, 0.11 to 0.33 clusters could be
expected to be the result of polyembryony, not vertebrate caching activities. At the
scale of this project, polyembryony probably has very little impact; regionally, it could
account for clusters outside of the nutcrackers reliable range.
Additionally, it is possible that two or more seeds could fall from the dehiscent
cones and be washed by rainwater into a suitable site. In three species of wind-
dispersed pines, Torick et al (1996) showed that tree clumps occurred at frequencies
of 12-40% and that 20-80% of clumps were in fact clusters. However, it was unclear
weather these caches were collections of wind blown seeds or vertebrate caches.
WTiile plausible, this is unlikely and probably not important with respect to the genetic
44


landscape.
Somatic mutations among the branches of multi-trunked individuals may
suggest a multi-genet cluster when, in fact, they are not. It is doubtful that allozyme
analysis would detect this and as such, somatic mutations are probably not important
within the scope of this study.
Overall relatedness (0.1602) across the sampled populations of southwestern
white pine reveals a relatively low level of family structure within clusters, particularly
in comparison to previous studies of bird dispersed pines (e.g., Carsey and Tomback
1994; Fumier et al. 1987). However, Schuster and Mitton (1991) found a similar level
of relatedness (0.19) for limber pine at Pawnee Buttes in eastern Colorado.
Additionally, relatedness averaged across the two sites within the nutcrackers range
was much lower than that obtained outside the birds range (Tab. 4.7).
Average relatedness among stems within clusters between the four sites varied
far more that expected, and is difficult to interpret. Both Williams Creek and Wolf
Creek Pass had lower than expected relatedness values, 0.1359 and -0.2829,
respectively. These values are unexpected for stands suspected of being derived from
Clarks nutcracker caching activities and reflect a low amount of family structuring,
even below that expected for half-sibs (0.25) and below expectations for avian seed
dispersal. Generally, relatedness among cache mates with dispersal by nutcrackers is
fairly high, as seeds are often derived from the same tree or even the same cone and
45


should share approximately 50% of their genetic material. However, due to potential
mixing of seeds in the birds sublingual pouch (Tomback 1988) or reburying of caches
by nutcrackers (Tomback 1978), it is possible for highly unrelated seeds to be placed
in the same cache. Episodic cone production in southwestern white pine (Krugman
and Jenkinson 1974) could also contribute to the low levels of relatedness observed;
cache-mates would have a higher probability of being derived from different trees.
Conversely, relatedness at Onion Saddle and Madera Canyon was much higher
than expected, 0.7711 and 0.5539, respectively. These values are similar or greater
than would be expected for full-sibs (50%). This indicates that clusters outside the
birds range were predominantly derived from seeds sharing a parent. This high
relatedness may also be due to seeds falling and becoming established directly under
the parent trees. .Alternatively, it may reflect the low dispersal distances found with
rodent dispersal of seeds. With respect to Onion Saddle and especially Madera
Canyon, where there is a lot of regeneration, but few clumps or clusters, dispersal is
apparently being effected primarily by a vertebrate that predominantly caches single
seeds, such as the Stellers jay.
Ecological and historical differences between the study sites clearly confound
any interpretation of the data, with respect to seed dispersers. Samano and Tomback
(2003) documented the use of southwestern white pine by Clarks nutcracker at the
Williams Creek site, the impacts of which are further revealed here. However, the
46


low relatedness among stems within clusters was not expected, and is not entirely
consistent with the harvesting and caching behavior of Clarks nutcracker, which
typically involves caching several to many seeds from one cone or tree. While I
expected Wolf Creek Pass to have a similarly high frequency of clusters, this was also
not the case due, in part, to low levels of recruitment. The nutcracker may utilize
open sites following a forest disturbance (i.e., fire) for many years; however, Wolf
Creek Pass appears to have fallen out of favor as a caching location with its succession
to a mixed-conifer forest.
Fluctuations in the nutcrackers range (Westscott 1964) may result in relictual
clusters outside of the birds reliable range. Northern areas of southwestern white
pines range may see heavy nutcracker caching activities in irruption years, then little
or no activity in intervening years. However, Clarks nutcrackers may not cache as
frequently, or at all, during these irruption events. Even with caching, the number of
multi-genet clusters is still expected to be lower in frequency than within the birds
primary range. This was the pattern expected at both Onion Saddle and Madera
Canyon, both of which showed little to no evidence of seed dispersal by Clarks
nutcracker. However, other corvid birds, such as Stellers jays, are known to cache
pine seeds, although generally in single (occasionally two or three) seed caches
(Vander Wall and Baida 1981). Rodents can also be effective seed cachers and seed
dispersers, albeit over much smaller distances (Vander Wall 1992a, 1992b, 1994). In
47


fact, recent work has revealed the importance of rodents in dispersing limber pine
seeds outside the range of Clarks nutcracker (Tomback et al., in prep). Caching by
other corvids or rodents could account for the few clumps at Onion Saddle and
Madera Canyon. However, these single seed caches are expected to affect a stands
genetic structure less.
Corvid seed caching activities can have important ecological and evolutionary
impacts on pine species. While the mutualistic relationships between Clarks
nutcrackers and many white pines (e.g., limber and whitebark pine) are well
established, the nature of this relationship for southwestern white pine is not. In the
case of southwestern white pine, a known food source for Clarks nutcracker where
the two are sympatric, the mutualism may not be as tight as has been shown for
limber pine and whitebark pine. Southwestern white pine differs from other
nutcracker-dependent pines with respect to most characters, excepting its large
wingless seeds. Furthermore, a large part of southwestern white pines distribution is
outside that of the Clarks nutcracker. Nonetheless, its wingless seed morphology
indicates a reliance on vertebrate seed dispersal.
While this study shows that tree clumps and clusters do occur in southwestern
white pine outside of the range of Clarks nutcrackers, the relationships between avian
seed caching and the population genetics of southwestern white pine are complicated
and not easily elucidated. The interpretation of these data may be confounded by
48


substantial dissimilarities between the four study sites (e.g., disturbance history, local
conditions, etc.) Additionally, it is probable that corvids other than Clarks nutcracker
play an important role in southwestern white pine seed dissemination; however, their
tendency to cache single seeds may obscure their impact on this species population
genetics. Seed caching by rodents may also be an important means of seed
dissemination for southwestern white pine, as has been shown for the Williams Creek
stand in southern Colorado. Detailed examination of the spatial genetic relationships
among all tree sites within a plot may provide further insight into what animals are
dispersing southwestern white pine seeds. Additional fieldwork increasing the
number of study sites, both within and outside of the Clarks nutcrackers range,
should help to clarify the nutcrackers role in southwestern white pine seed dispersal.
Sites that are well outside of the nutcrackers range would be particularly useful for
comparisons between nutcrackers and other vertebrate seed dispersers impacts on
the population genetics of southwestern white pine.
49


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58


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59


Appendix 1. Tree species encountered in transects through each of four Pinus strobiformis Engelmann (Pinaceae)
study sites in Arizona and Colorado.____________________________________________________________________________
Williams Creek, Colorado Wolf Creek Pass, Colorado Madera Canyon, Arizona Onion Saddle, Arizona
Abies concolor (Gord. & Glend.) Hildebr. Abies concolor (Gord. & Glend.) Hildebr. Juniperus deppeana Steud. Juniperus deppeana Steud.
Picea engelmannii Parry ex Engelm. Pinus strobiformis Engelm. Pinus arizonica Engelm. Pinus arizonica Engelm.
Pinus ponderosa Dougl. ex Laws. Populus tremuloides Michx. Pinus strobiformis Engelm. Pinus discolor D. K. Bailey & Hawksw.
Pinus strobiformis Engelm. Pseudotsuga menziesii (Mirb.) Franco Quercus gambelii Nutt. Pinus engelmannii Parry ex Engelm.
Populus tremuloides Michx. Quercus hypoleucoides A. Camus Pinus strobiformis Engelm.
Pseudotsuga menziesii (Mirb.) Franco Quercus rugosa Nee Pseudotsuga menziesii (Mirb.) Franco Quercus arizonica Sarg. Quercus gambelii Nutt. Quercus hypoleucoides A. Camus


Appendix 2. Electrophoretic phenotypes for ten allozyme loci examined in Pinus
strobiformis Engelmann (Pinaceae) at four study sites in Arizona and Colorado.
Individual clump ______________________________________Loci______________________
ID number AAT1 AAT2 ACPH IDH MDH2 PER1 PER2 PGD2 PGM1 SDH1
William's Creek
4a clump4 a/a c/c b/b a/b a/a a/a b/b a/a a/a b/b
4b clump4 a/a c/c b/b b/b a/a a/a b/b a/b a/a b/b
9a clump9 a/a c/c b/b b/b a/a a/a b/b a/b a/a b/b
9b clump9 a/a c/c b/b b/b a/a b/b c/c a/a a/a b/b
10a clumpIO a/a c/c b/b b/b a/a b/b c/c a/b a/a b/b
10b clumpIO a/a c/c b/b b/b a/a b/c b/c a/a a/a b/b
15a clump15 a/a a/c b/b b/b a/a a/a a/b a/a a/a b/b
15b clump15 a/a c/c b/b b/b a/a a/a b/b a/a a/a b/b
15c clump15 a/a c/c b/b b/b a/a a/d a/b a/a a/a b/b
16a clump16 a/a c/c b/b b/b a/a a/a b/b a/a a/a b/b
16b clump16 a/a c/c b/b b/b a/a a/a b/b a/a a/a b/b
18a clump18 a/a c/c b/b b/b a/a a/c b/b a/a a/a b/b
18b clump18 a/a c/c b/b b/b a/a a/c b/b a/a a/a b/b
28a clump28 a/a c/c b/b a/b a/a a/b b/b a/b a/a b/b
28b clump28 a/a c/c b/b b/b a/a b/b b/b a/b a/a b/b
36a clump36 a/a c/c b/b b/b a/a a/c b/b a/a a/a b/b
36b clump36 a/a c/c b/b b/b a/a a/c b/b a/a a/a b/b
36c clump36 a/a c/c b/b b/b a/a a/c b/b a/a a/a b/b
39a clump39 a/a c/c b/b b/b a/a b/c b/b a/b a/a b/b
39b clump39 a/a c/c b/b b/b a/a c/c b/b a/a a/a b/c
40a clump40 a/a c/c b/b b/b a/a a/c b/b a/a a/a b/b
40b clump40 a/a c/c b/b b/b a/a c/c b/b a/a a/a b/b
41a clump41 a/a c/c b/b b/b a/a a/a b/b a/a a/a b/b
41b clump41 a/a c/c b/b b/b a/a a/a a'/b a/a a/a b/b
42a clump42 a/a c/c b/b b/b a/a a/c b/b a/a a/a b/b
42b clump42 a/a c/c b/b b/b a/a c/c b/b a/a a/a b/b
54a clump54 a/a c/c b/b b/b a/a a/c b/b a/a a/a b/b
54b clump54 a/a c/c b/b b/b a/a a/d b/b a/b a/a b/b
58a clump58 a/a c/c b/b a/b a/a a/c b/b a/a a/a b/b
58b clump58 a/a c/c b/b b/b a/a b/d b/c a/a a/a b/c
70a clump70 a/a c/c b/b b/b a/a a/b b/c a/b a/a b/b
70b clump70 a/a c/c b/b b/b a/a a/a b/b a/a a/a b/c
78a clump78 a/a c/c b/b b/b a/a a/c b/b a/a a/a b/b
78b clump78 a/a c/c b/b b/b a/a a/c b/b a/a a/a b/b
Williams Creek (transects)
1a clumpl a/a c/c b/b a/b a/a a/a b/b a/a a/a b/b
1b clumpl a/a c/c b/b b/b a/a a/a b/b a/a a/a b/b
2a clump2 a/a c/c b/b b/b a/a b/c b/c a/a a/a b/b
2b clump2 a/a c/c a/b b/b a/a a/d a/b a/a a/a b/b
2c clump2 a/a c/c b/b b/b a/a c/c b/b a/a a/a b/b
61


Individual clump Loci
ID number AAT1 AAT2 ACPH IDH MDH2 PER1 PER2 PGD2 PGM1 SDH1
3a clump3 a/a c/c b/b b/b a/a a/c b/b a/b a/a b/b
3b clump3 a/a c/c b/b b/b a/a b/d a/a a/a a/a b/c
3c clump3 a/a c/c b/b b/b a/a a/c b/b a/b a/a b/b
4a clump13 a/a c/c b/b b/b a/a a/d b/b a/a a/a b/b
4b clump13 a/a c/c b/b b/b a/a c/d b/b a/b a/a b/b
5a clump14 a/a c/c b/b b/b a/a a/d a/b a/a a/a b/b
5b clump14 a/a c/c b/b b/b a/a a/a b/b a/a a/a b/b
Madera Canyon
22a clump22 a/a c/c b/b b/b a/a a/a b/b a/a a/a a/b
22b clump22 a/a c/c b/b b/b a/a a/a b/b a/a a/a a/b
Madera Canyon (transects)
1a clump5 a/a c/c b/b b/b a/a a/a b/b a/a a/a b/b
1b clump5 a/a c/c b/b b/b a/a a/a b/b a/a a/a a/b
1c clump5 a/a c/c b/b b/b a/a a/a b/b a/a a/a b/b
2a clump6 a/a c/c b/b b/b a/a a/a b/b a/a a/a b/b
2b clump6 a/a c/c b/b b/b a/a a/a b/b a/b a/a a/b
3a clump7 a/a c/c b/b b/b a/a a/a a/b a/b a/a b/b
3b clump7 a/a c/c b/b b/b a/a a/a b/b a/a a/a b/b
4a clump8 a/a c/c b/b b/b a/a a/a a/b a/a a/a a/b
4b clump8 a/a c/c b/b b/b a/a a/a a/b a/a a/a b/b
Onion Saddle
11a clurnpH a/a c/c b/b b/b a/a b/b a'/b a/a a/a a/b
11b clumpH a/a c/c b/b b/b a/a b/b a'/b a/a a/a a/b
57a clump57 a/a c/c b/b b/b a/a b/b a'/b a/a a/a a/b
57b clump57 a/a c/c b/b b/b a/a b/b a'/b a/a a/a b/b
77a clump77 a/a c/c b/b b/b a/a b/b a/b a/a a/a b/b
77b clump77 a/a c/c b/b b/b a/a b/b a'/b a/a a/a b/b
109a clump109 a/a c/c b/b b/b a/a a/a b/b a/a a/a b/b
109b clump109 a/a c/c b/b b/b a/a a/a b/b a/a a/a b/b
Wolf Creek
11a clump12 a/a c/c b/b b/b a/a a/a b/b a/a a/a b/b
11b clump12 a/a c/c b/b b/b a/a a/a a/a a/a a/a a/b
20a clump20 a/a c/c b/b b/b a/a a/b b/b a/a a/a b/b
20b clump20 a/a c/c b/b b/b a/a a/c a/a a/b a/a b/b
24a clump24 a/a c/c b/b b/b a/a a/d a/a a/a a/a b/b
24b clump24 a/a c/c b/b b/b a/a a/d a/a a/a a/a b/b
80a clump80 a/b c/c b/b b/b a/a a/b a'/b a/a a/a b/b
80b clump80 a/a c/c b/b b/b a/a a/a b/b a/a a/a a/b
80c clump80 a/a c/c b/b b/b a/a a/d a/a a/a a/a b/b
95a c)ump95 a/a c/c b/b b/b a/a d/d b/b a/a a/a a/b
95b clump95 a/a c/c b/b b/b a/a a/d b/b a/a a/a b/b
95c clump95 a/a a/c b/b b/b a/a d/d a/b a/a a/a b/b
95d clump95 a/a c/c b/b b/b a/a b/b a'/b a/a a/a b/b
62


Appendix 3. Relatedness values for all Pinus strobiformis
Engelmann (Pinaceae) clumps sampled at four study sites in
Arizona and Colorado.
Relatedness by clump#
Value: R: Nx,Ny: J/loci: C.I.: Pseud.:
clump4 0.4175 2,2 0.7322 1.6562 10
clump9 -0.5983 2,2 0.1802 0.4077 10
clumpIO 0.4104 2,2 0.2198 0.4972 10
clump15 0.2949 3,3 0.3753 0.8490 10
clump16 1.0000 2,2 0.0000 0.0000 10
clump18 1.0000 2.2 0.0000 0.0000 10
clump28 0.3985 2,2 0.3748 0.8477 10
clump36 1.0000 3,3 0.0000 0.0000 10
clump39 0.2287 2,2 0.5964 1.3490 10
clump40 0.7397 2,2 0.2608 0.5899 10
clump41 0.7047 2,2 0.4210 0.9524 10
clump42 0.7397 2,2 0.2608 0.5899 10
clump54 0.1468 2,2 0.7224 1.6341 10
clump58 -1.0619 2,2 0.5782 1.3078 10
clump70 -0.6406 2,2 0.7517 1.7003 10
clump78 1.0000 2,2 0.0000 0.0000 10
clump22 1.0000 2,2 0.0000 0.0000 10
clump11 1.0000 2,2 0.0000 0.0000 10
clump57 0.7711 2,2 0.6371 1.4411 10
clump77 1.0000 2,2 0.0000 0.0000 10
clump109 1.0000 2,2 0.0000 0.0000 10
clump12 -0.0422 2,2 0.8722 1.9729 10
clump20 -0.7039 2,2 0.3208 0.7257 10
clump24 1.0000 2,2 0.0000 0.0000 10
clump80 -0.4530 3,3 0.3645 0.8245 10
clump95 0.0677 4,4 0.3297 0.7457 10
clumpl 0.7240 2,2 0.3759 0.8503 10
clump2 -0.1337 3,3 0.3195 0.7227 10
clump3 -0.6319 3,3 0.2354 0.5325 10
clump13 0.2884 2,2 0.4901 1.1086 10
clump14 0.2830 2,2 0.3011 0.6810 10
clump5 0.8133 3,3 0.2578 0.5832 10
clump6 0.3983 2,2 0.7861 1.7782 10
clump7 0.3615 2,2 0.8782 1.9866 10
clump8 0.6426 2,2 0.6810 1.5403 10
Settings for R calculation:
Px Setting: Use All Weighted by clump#.
Py Setting: (K-clump# = X) Frequency bias uncorrected.
63