A STUDY ON THE EFFECTIVENESS OF TRANSPLANTING VS. SEEDING OF LUPINUS PERENNIS IN AN OAK SAVANNA REGENERATION SITE
Mark K. St. Mary
A Thesis
Submitted to the Graduate College of Bowling Green State University in partial fulfillment of the requirements for the degree of
MASTER OF SCIENCE
August 2007
Committee:
Helen J.Michaels, Advisor
Jeffery G. Miner
Daniel M. Pavuk
ii
ABSTRACT
Helen J. Michaels, Advisor
Lupinus perennis (Fabaceae) is an indicator species for savanna and barrens habitat throughout the Great Lakes region and northeastern United States. It is also the sole larval food source for the federally endangered Karner blue butterfly (Lycaeides melissa samuelis) and an important food source for other threatened butterfly species. Although butterfly recovery programs include restoration of existing lupine populations and establishment of new ones, the determination of the optimum conditions and method of lupine repopulation has received little attention. This study compared the survival, growth and reproduction of L. perennis for two growing seasons after planting. Seed and greenhouse grown transplants from four population sources were planted across naturally occurring gradients of light, soil moisture, pH, phosphorous, and soil surface materials along field transects in a savanna restoration. Estimates of labor required in the production, planting and aftercare of both greenhouse plants and seeds were also compared. Both population source and substrate type significantly influenced seedling emergence, while survival decreased with increased light levels, herbivory, and disturbance. As expected, transplants had significantly greater survival than seedlings, but were also affected by initial size, population source, herbivory and disturbance. Seedling size was influenced by population source, light, and soil pH, while transplant size varied only with population and light.
Only 1% of seedlings flowered in the second season, compared to 25% of transplants. Only population source had a significant effect on seed production by the transplants. Although approximately 9.5 times more labor was required for transplants, they outperformed the seedlings in survival, size and potential fecundity in the first two seasons. Optimal planting iii
locations and the relative merits of establishing populations of L. perennis within butterfly habitat regeneration projects are discussed.
KEY WORDS: Lupinus perennis; savanna restoration; seeding; transplants; Lycaeides melissa samuelis; butterfly habitat iv
ACKNOWLEDGEMENTS
I would like to thank Helen Michaels for the knowledge, time and advice she was able to
give me as my advisor. In addition, I would like to thank Jeff Miner and Dan Pavuk for their
advice and support as committee members.
Special thanks go to my wife and partner, Marcia Hunt, without whose love,
understanding and encouragement I would not have been able to complete this project.
Marcia Hunt assisted me in the greenhouse planting and data collection. Marcia Hunt
and Chris Tracey provided their time and labor in the field planting. Chris Tracey, Scott
Hevner, and Chris Davis provided input in designing the study. Heather Strohschein assisted
with the soil testing and data entry. Dan Wiegmann and Nancy Boudreau provided valuable insight and advice on the statistics.
Access to the field site was provided by The Metropolitan Park District of the Toledo
Area. Materials were courtesy of the Ohio Chapter of The Nature Conservancy, the Ohio
Department of Natural Resources, and the Michigan Department of Natural Resources. Special thanks to John Jaeger, Jerry Jankowski, and Bob Jacksy of The Metropolitan Park District of the
Toledo Area for their support and encouragement.
v
TABLE OF CONTENTS
Page
ABSTRACT…………………………………………………………………………… ii
ACKNOWLEDGEMENTS…………………………………………………………… iv
TABLE OF CONTENTS……………………………………………………………... v
LIST OF FIGURES…………………………………………………………………… vi
LIST OF TABLES……………………………………………………………………. vii
INTRODUCTION……………………………………………………………………. 1
METHODS……………………………………………………………………………. 5
Materials………………………………………………………………………. 5
Greenhouse Production………………...…………………………………….... 5
Site Selection…………………………..………………………………………. 6
Data Collection…………………………………..…………………………….. 9
Data Analysis………………………………………………………………….. 12
RESULTS……………………………………………………………………………… 14
DISCUSSION…………………………………………………………………………. 29
LITERATURE CITED………………………………………………………………... 37
vi
LIST OF FIGURES
Figure Page
1 The spacing of plants and seeds at transect points in the field………………. 8
2 ANOVA means of the log of number of days to seedling emergence by planting substrate……………………………………………………...... 16
3 Survival of seedlings and transplants through June of each year………….… 17
4 Seedling survival at three points in time by population…………………….. 19
5 Transplant survival through late June of each year by population………….. 20
6 Mean size of seedlings by population source in June of each year…………. 23
7 Mean size of seedlings by planting substrate in June of each year…………. 23
8 Mean size of transplants, at three points in time, by population source……. 25
9 Mean size of transplants, at three points in time, by planting substrate……. 26
10 Mean number of seeds produced by transplants in 2002 and 2003 and by seedlings in 2003……………………………………………………….. 28
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LIST OF TABLES
Table Page
1 Source of seeds by their populations………………………………………… 5
2 Deviations from the average for rainfall and temperature for Toledo, OH in 2002 and 2003……………………………………………….. 14
3 Environmental variables measured…………………………………………... 14
4 Correlations of environmental variables……………………………………... 15
5 Logistic regression on seedling survival through June, 2002………………... 18
6 Logistic regression on seedling survival from June, 2002 to June, 2003……. 18
7 Logistic regression on transplant survival through June, 2002……………… 20
8 Logistic regression on transplant survival from June, 2002 to June, 2003….. 20
9 Deviations from the average for rainfall and temperature for Toledo, OH in 2002 and 2003……………………………………………….. 21
10 GLM of the log of size of seedlings in June, 2002…………....……………. 22
11 GLM of the log of size of seedlings in June, 2003……………….………… 22
12 GLM of square root of size of transplants in June, 2002…………………… 24
13 GLM of square root of size of transplants in late June, 2003………………. 25
14 Logistic regression on the probability of flowering in 2002………………... 27
15 Logistic regression on the probability of flowering in 2003………………... 27
16 Logistic regression on the probability of seeding in 2002………………….. 27
17 Logistic regression on the probability of seeding in 2003………………….. 27
18 GLM of the log of number of seeds produced in 2003…………….. ……… 28
1
INTRODUCTION
Perennial blue lupine, Lupinus perennis L.(Fabaceae), is one of the plant species regarded as an indicator species for savanna and barrens habitat (Voss 1985) and has been shown to be an integral part of the biota of many savanna, prairie and barrens habitats across the northeastern parts of the United States and southeastern Canada (Smallidge et al. 1996). Savannas and barrens containing L. perennis are found in Ontario, Canada and across the Great Lakes region from Minnesota to New York and in parts of New Jersey and southern New England (Anderson,
Fralish, & Baskin 1999, Mitchell 2001). Colonies are found in areas of well-drained, sandy soils with little to no competition from surrounding vegetative cover, and in light levels from full sun to partial shade (Mackay et al. 1996). L. perennis plants are often found in association with other savanna plants such as little bluestem (Schizachryium scoparium)(Poaceae), lyre-leaf rock cress (Arabis lyrata)(Brassicaceae), butterfly milkweed (Asclepias tuberosa)(Asclepiadaceae),
and white flowering spurge (Euphorbia corollata)(Euphorbiaceae)(Swink 1974).
Lupinus perennis is considered a pivotal plant because of its relationship with a number
of important insects. It has been identified as the sole larval food source for the Karner blue
butterfly (Lycaeides melissa samuelis), a federally endangered species (Grundel et. al. 1998a),
and is a primary larval food source and adult nectar source for two other butterflies, the Persius
duskywing (Erynnis persius) and the frosted elfin (Callophrys irus) (Iftner 1992; Opler 1995).
The Persius duskywing is endangered in the states of Connecticut, Massachusetts, Minnesota,
New Hampshire, New York and Ohio, and is threatened in Michigan (Sheperd, Vaughan, and
Black, 2005). The frosted elfin is endangered in Delaware, Maryland, New Hampshire and Ohio 2
and threatened in Connecticut, Michigan, New Jersey, New York and Wisconsin (Sheperd,
Vaughan, and Black 2005).
Because of its importance in the life cycle of these rare butterflies, the repopulation of L.
perennis in restored savannas, barrens, and prairies is critical for sustaining the biotic diversity
that such habitats are capable of supporting and for the preservation of the Karner blue butterfly
(WDNR 2001) as well. However, throughout the midwestern region of the United States, oak
barrens and savanna have declined by 98% from pre-settlement acreage (Nuzzo 1986). Within
the Oak Openings region of northwest Ohio, less than 1% of the original oak savanna habitat
exists (Brewer and Vankat 2004). The regeneration and maintenance of L. perennis habitats are
the primary methods by which federal, state, and local conservation agencies and groups plan to
save this species of butterfly (Tolson 1998: WDNR 2001).
Lupinus perennis is listed as a species of concern in the states of Iowa, Maine, Maryland,
New Hampshire, New Jersey, Ohio, Pennsylvania and Vermont (USDA 2007). Within the state of Ohio, L. perennis is primarily limited to the Oak Openings region in northwest Ohio, which spans Lucas, Fulton, and Henry counties. It has been extirpated from four Ohio counties since
1970 (ODNR 2001). Habitat loss from overgrowth of successional woody species due to fire suppression has been cited as the main reason for the decline in population levels of this species
(ODNR 2001). Agencies such as the Metropolitan Park District of the Toledo Area, The Nature
Conservancy, and the Ohio Department of Natural Resources have attempted to regenerate the prairie and savanna habitats of the Oak Openings Region primarily by mechanical thinning, mowing, and the controlled burning of natural areas, preserves, and right-of-ways (Smallidge &
Leopold 1997: Abella 2001). In many cases, the reopening of the canopy is enough for the remnant grasses and forbs to spread and reestablish themselves (Abella 2001). However, in sites 3
where some of the former resident plant species have been extirpated, new colonies of plants
may have to be reintroduced through the planting of seeds or nursery grown plants.
Studies have found that a need exists for the reestablishment of large populations of L. perennis as a means of preserving habitat for the aforementioned butterflies, yet the determination of the optimum location and method of L. perennis reintroduction has received little attention. To date, most research on this species has focused on the plant as a food source for the larvae of the Karner blue butterfly (Grundel et al. 1998a, Grundel et al. 2000: Mackay et al. 1996), effects of fire (Grigore & Tramer 1996), and general environmental preferences of the
plant (Boyonoski 1992, Kelly 1998).
Although these facts are important in our growing understanding of L. perennis
reestablishment, a comprehensive literature search indicates a gap in our knowledge concerning
practical aspects of restoring lupine to habitats. Specifically, it is not known whether perennial
blue lupine fares better if reintroduced into a landscape through the planting of seeds or from nursery grown potted plants. Additionally, it is important to determine if this species will better establish itself in areas of bare soil or soils with other surface coverings, such as organic matter, moss, or a cryptogrammic crust.
These types of questions are important not only to expand the knowledge base on this species, but for practical applications as well. As the remaining populations of L. perennis for
many savanna regeneration projects, if they exist, are relatively small, the availability of native
seed is limited and thus it is important to make the most of each seed. Knowing when, where,
and how lupine should be reintroduced will help to conserve resources and more rapidly restore
or establish self-sustaining populations of this species. 4
This study was designed to compare the survival and growth of L. perennis introduced as
plants and as seed across a natural, heterogeneous gradient of light levels and soil surface materials at the site of an ongoing savanna regeneration project. The study investigated differences in initial survivorship, growth rates, and potential fecundity between plants resulting from direct seeding and those of nursery-grown plants that were transplanted to the site.
It was expected that due to transplant shock and damage by animals, the initial recruitment of plants from the planting of pot grown plants would be lower than that of the seeds, but the surviving transplants would have a greater chance of blooming and producing seed in the first year due to a three-month “head start” in growth. However, it was also expected that the size of surviving seedlings would equal the size of the nursery-grown transplants by the second season.
5
METHODS
Materials
The material for this study was seed of L. perennis that were collected in July, 1998 for use in genetic studies of lupine as described in Shi (2004). The four source populations were
from the Oak Openings region: a prairie regeneration site in the Petersburg State Game Area
(Michigan), a sand dune blowout at the Mielke Rd. Savanna, the Nature Conservancy’s South
Piel site at Kitty Todd Preserve and the Lou Campbell State Nature Preserve “central” site. The
source location and sample sizes for seeds and transplants are shown in Table 1.
Population Latitude Longitude # of Seeds # of Plants # of Seeds Source planted in transplanted planted on greenhouse to the site site
Blowout 41.6398 -83.7655 107 58 103 Piel 41.6182 -83.7852 235 127 221 Petersburg 41.8746 -83.6945 279 131 282 Central 41.5918 -83.7776 279 132 290
Total 900 448 896
Table 1. Source of seeds by their populations, with the location coordinates of the source population and sample sizes of lupine plants and seeds.
Greenhouse Production
To produce transplants for this field study, seeds from the four populations were planted in a research greenhouse on February 2, 2002. To maximize germination, seeds were mechanically scarified by nicking the seed coat with a razor (Mackay et al. 1996), a typical method used for seeds with a hard seed coat. They were then placed in 10 cm petri dishes with sterilized sand, moistened with deionized water and refrigerated overnight for a short cold moist treatment (Kelly 1998). The seeds were planted in Fafard # 52 potting mix in tree-band pots (7 cm on a side x 14 cm high for a total soil volume of 686 cm3) and placed on benches, in a 6
random order, in a climate-controlled greenhouse (approximately 22°C day/14°C night).
Because L. perennis is a legume capable of fixing nitrogen through a mutualism with bacteria of
the genus Rhizobium (Alexander 1984), the seeds were inoculated at planting time with Type H
Rhizobium sp. (LiphaTech, Milwaukee, WI) to promote root nodule development. High intensity lighting, using 1000 watt metal halide lamps, supplemented the relatively low available light of the winter days (producing an average of 647 µE m -2 s-1, measured approximately 10 cm above the plants on an overcast day, with a 14 hour day length). During their three month stay in the
greenhouse, the trays of seedlings were twice moved to other benches to reduce potential micro-
climatic variation within the greenhouse. The seedlings were checked daily and watered as
needed.
In order to produce seedlings of sufficient size to transplant to the study site by the first
of May, they were given supplemental fertilization. After 75% of the seedlings had developed a
second true leaf, beginning on March 3, the plants were fertilized once a week for three weeks
with a 1:1 blend of two water soluble fertilizers (Miracle-Gro®, 15-30-15 and Miracid®, 30-10-
10) at a rate of 3.94 ml /L (1 tablespoon per gallon of water). To reduce the chance of the plants
being too succulent when planted, fertilization was discontinued after March 22, five weeks
before the intended planting time. The plants were moved outside on April 14 for hardening off,
acclimating to the colder outdoor temperatures before being planted in the field. Upon leaving
the greenhouse, the leaves were counted and the largest leaf was measured across the widest
point on each plant.
Site Selection
The location selected for this study was in the Reed Road Dunes area in the Oak
Openings Preserve Metropark in western Lucas County, Ohio. This area, historically a savanna 7
site, had been the subject of limited regeneration work during the three years prior to the study
and had approximately two dozen extant L. perennis plants from a trial planting the previous summer. There were several areas within the site that were considered good candidates for the re-introduction of perennial lupine. As this study was intended to increase the knowledge of the planning and implementation of the re-establishment of L. perennis for savanna regeneration programs, planting plot transects were selected to mimic the sites where L. perennis were currently found growing in the Oak Openings region. These are usually relatively open areas with well-drained, sandy soil with little competition from established grasses or forbs. Six transects, from 48 to 84 m long, crossed a variety of microhabitats, from partial shade to full sun and from bare sand to a layer of decomposing organic matter on the surface of the soil. The plants and seeds were planted along a series of transects through areas of this site with a sporadic cover of savanna species that were devoid of L. perennis.
Planting occurred in two rows of three on both sides of each transect point (Figure 1),
where each group of six planting points included two plants and four seeds with a minimum of
0.5 m spacing between each point (Powell 1995). There was a 1.5 m space between each
planting group to provide access to the experimental plants for monitoring purposes and
minimize impact to neighboring test plants. Before the field study began, the planting points
along all transects were numbered sequentially and a random selection method (blind drawing of marked coins) was used to decide what would be planted at each point. First drawn was the determination of transplant or seed, then the source population. With the exception of the limited numbers of plants and seeds from the Blowout population, there was one plant and two
seeds from each population at each transect point. Each plant or seed was planted at least 10 cm
from any existing plants. At the time of planting, each transect was carefully mapped with the 8 location of each plant and seed. The ends of each transect were marked with re-bar to facilitate relocation of the materials for data collection during the study.
0.5m 1.5 m S X S S P X S S .5 m P S X P P SX S
1.0 m
P X S S SX P P S P X S S SX S
Figure 1. The spacing of L. perennis plants (P) and seeds (S) on either side of two points of a transect. Four possible arrangements of seed and plant positions are shown. The location of environmental sampling points is indicated by (X). There were seven transects and 112 transect points.
The field-planted seeds were scarified and Rhizobium inoculated in the same manner as the seeds used in the greenhouse transplant production to allow for roughly equivalent starting conditions as it was not known whether the bacteria occurred naturally in the native soil of the study site. However, in order to reduce the possibility of inducing germination during unfavorable weather conditions, the field planted seed were not given an overnight cold moist treatment.
The field planting for the study occurred on April 30, May 1 and 2, 2002. When the greenhouse transplants were planted (4/30-5/1), any surface layer of loose, decomposing organic matter was temporarily moved aside, and each plant was removed from its pot and placed in a hole that was slightly larger than the tree-band pot. Soil that had been removed was then replaced so that the top of the root ball of the plant was even with the surrounding soil grade, and the surface organic material that had been removed was then replaced around the newly planted 9
plant. Care was taken not to smother the plant with the replacement of an excessive amount of this material (i.e. more than two centimeters). Any excess organic matter was lightly scattered around the planting site.
All seeds were planted on May 2. Initially the surface layer of loose, decomposing
organic material was removed to create a 15 cm diameter exposed area of soil. The seeds were
then pressed into the soil to a depth equal to twice their size (~ 1 cm). The surface organic
material that had been removed was replaced in the same manner as with the planting of the
plants. To ensure good soil contact, the plants were watered immediately after planting and again the following day with approximately 500 ml of water per transplant per watering. The seeds were watered once after planting with approximately 250 ml of water per planting point.
As there were frequent light rains in the two weeks following planting, subsequent watering was not needed to establish the transplants or seedlings.
Site Data Collection
A variety of environmental factors were measured for each transect at the outset of the study. During the first week of May, soil cores, to a depth of ten cm, were taken at each planting group, a total of four at each transect point at the positions indicated by the “x” marks in Figure
1. The 448 soil samples were tested for soil moisture gravimetrically and pH with a Corning pH meter (Model 420, 476580 electrode). Phosphorus was extracted from 126 of the samples with a
Mehlich 3 extractant solution and quantified colorimetrically using an ammonium molybdate method for atomic absorption spectrophotometry (CANR 1995). The results were scored to the three planting points nearest to each sampling point. Due to complications with timing, the soil 10
samples were not tested for available nitrogen, but it was assumed to be low throughout the site due to the sandy soil and evidenced by the sparse plant growth.
At the time of planting, the type of soil substrate in which each transplant or seed was planted was scored using five categories (sand, moss/crust, fine organic matter, coarse organic matter, and coniferous organic matter). The sand category was assigned when the planting point was in bare soil. Moss/crust included planting points with a covering of moss or cryptogamic crust. Fine organic matter was defined by coverage of degraded, non-coniferous organic matter with a particle size of four cm or less. Coarse organic matter planting points had whole and partially degraded (>4 cm) leaf litter, while planting sites scored as coniferous were in areas where red pine (Pinus resinosa) trees had been removed the previous year but had retained a cover of degraded needles and bark. Neither the fine nor coniferous organic matter layers exceeded 2 cm in depth and the coarse organic matter was proportionately limited.
Each planting group was also sampled for photosynthetically available light (µE m−2 s−1) using a LI - 190SA quantum sensor (LI-COR Inc, Lincoln, NE) during the last week of May,
2002. Using a clear, one m long Plexiglas extension to avoid observer shadows, the sensor was
held level to the ground at a height of approximately ten cm. Light data were collected on sunny
days between 5/31/02 and 6/8/02. The measurements were made, at the same sampling points as
the soil cores, at three time points: morning (8-10 am), noon (11am-1pm), and afternoon (2-
4pm). Every five minutes, two readings were taken of the available light level by sampling the
light at one meter above the ground and at least ten meters from the nearest shade. At each
sampling point, two light readings were taken at approximately 15 second intervals. To find the
percentage of the relative amount of light that was available to the plants at that point, the
difference between the average of the sample point readings and the averaged available light 11 readings was divided by the available readings. Rainfall and temperature data were collected from the National Weather Service using the monitoring station at Toledo Express Airport, which was within 5 km of the study site.
The plants and seedlings were monitored daily for the first month after planting, after which twice weekly observations were made until mid-July, 2002. In 2003, the site was visited twice per week from mid-May through July. Data collected in 2002 included the number of days to cotyledon emergence (the point where the seed cotyledons had fully emerged from the soil and both had unfolded to lie in the same plane) and the number of days to the first true leaf
(when the leaflets had all fully unfurled and were lying in the same plane).
The size of the transplants at planting, the size of the transplants and seedlings in late
June of 2002 and June of 2003 were also recorded, using the number of fully expanded leaves multiplied by the width of the largest leaf to create a proxy variable for size. Obvious signs of damage from herbivory by insects or mammals, or evidence of root disturbance from surface digging or tunneling were also noted. In both 2002 and 2003, for plants that flowered and set fruit, the flower stalks were enclosed in polyester mesh bags, to protect them from deer browsing, allow the pods to safely mature, and collect seeds. Once mature and expelled from the pods, the seeds were collected and counted as a measure of potential fecundity.
One of the goals of this study was to identify the most efficient method of reintroducing
L. perennis to savanna regeneration projects, which are usually limited by funds available to agencies. Thus, to allow for a form of cost-benefit analysis, estimates of the number of man- hours involved in the production, planting and aftercare of both greenhouse plants and seeds were also noted.
12
Data Analysis
All statistical analyses were performed using SPSS 11.0 (SPSS Inc., Chicago, IL).
Spearman pairwise correlations were run to determine if there was strong colinearity between any of the independent variables. The probability of survival or flowering was analyzed through logistic regression. The variables of population source, substrate type, soil moisture, soil pH, and available light for May morning, noon, and afternoon were included in all tests. The number of days to emergence, size of the transplant at planting and size of transplant or seedling in June
of 2002 and 2003 were used in the survival and flowering tests, and incidences of herbivory and
root zone disturbance were included in the analyses of survival probabilities. Both forward
stepwise (p<0.05 for retention) and backward stepwise (p>0.10 for elimination) logistic
regressions were run to determine which variables significantly explained variation in the
dependent variables. The resulting variables were then entered in order from greatest to least
Wald value to develop the final model. If any of the variables from this final model were
categorical (such as population source or substrate type), a crosstabs test was run to determine
the relative influence of the categories on the dependent variable (Tabachnick and Fidell 2001a).
GLM was used to determine which of the variables had a significant effect on plant size
at various points in time and the number of seeds produced. Type I sum of squares was used in
the analyses (Tabachnick and Fidell 2001b). The models tested the main effects of population
and substrate type as well as their possible interaction. Available light for May morning, noon,
and afternoon and the number of days to seedling emergence were also included. Additional
variables of soil moisture, soil pH, the size of the transplant at planting, and size of transplant or
seedling in June of 2002 and 2003, were transformed to normal distributions before being 13 introduced to the analysis (Tabachnick and Fidell 2001b). If the resulting model included a categorical variable (population or substrate type), an ANOVA was run on that variable with a
Tukey HSD post hoc test to determine the significance of the individual categories. As it was difficult to quantify the extent of herbivory of the above ground plant material or disturbance of the root zone of the test plants, those plants that had experienced an obvious herbivory (24.6% of transplants, 16.6% of seedlings) or disturbance (13.4% of transplants, 1.1% of seedlings) event were not included in statistical analysis of plant growth, flowering, or seed production. Separate statistical tests were run on the smaller data set that included the variable of soil phosphorus.
14
RESULTS
The first month of the study was cooler and wetter than normal (NWS 2007), with measurable amounts of rain (0.025 mm – 39.12 mm) on 20 days with a total of 87.07 mm. In
June, rain fell on 12 days (0.025 mm – 24.13 mm) with a total of 50.80 mm and the temperature was warmer than normal (Table 2). The study site was generally sunny, with a rather dry acidic soil (Table 3).
Date Rainfall Deviation Temperature Deviation From Average From Average (mm) (o C)
May ‘02 + 10.16 - 1.10 June ‘02 - 45.72 + 2.00 Year ‘02 - 104.65 - 1.55
April ‘03 - 17.02 + 0.27 May ‘03 + 70.62 - 0.78 June ‘03 - 17.27 - 1.27 Year ‘03 + 103.38 - 0.22
Table 2. Deviations from the average for rainfall and temperature for Toledo, OH in 2002 and 2003. As measured at Toledo Express airport (~5 km from study site) (NWS 2007).
Variable Minimum Maximum Mean Morning Light (% of available light) 3 100 65.34
Noon Light (% of available light) 6 100 82.53 Afternoon Light (% of available light) 2 100 82.51 Soil Moisture (%) 0.59 26.86 6.18 Soil pH 3.44 5.00 3.96 Soil Phosphorus (ppm) 1.36 16.70 9.44
Table 3. Environmental variables measured at four locations at transect points in May of 2002. The light values are a percentage of available light and the soil moisture is a percentage of the soil mass.
15
Within the smaller data set (n=504), soil phosphorus correlated positively with soil pH
(r = 0.217, p<0.01) and noon light levels (r = 0.321, p<0.01) and negatively with soil moisture
(r = - 0.241, p<0.01). However, all of the correlations were relatively weak and soil phosphorus
was not a significant influence on any of the plant performance characteristics examined.
Therefore the remaining results were from analyses of the larger data set (n=1344).
Three general trends resulted from pairwise correlations of the environmental variables.
Specifically, increasing light level readings during the noon and afternoon periods were
associated with decreasing soil moisture, increased soil moisture was correlated with lower soil
pH, and noon light levels were correlated with morning and afternoon light levels. Although
statistically significant, the correlations were relatively weak (r <0.33) (Table 4).
May May May Soil a.m. noon p.m. moisture Soil pH light light light N 1344 1344 1344 1344 1344 Soil moisture Spearman's rho 1.000 Correlation Soil pH Spearman's rho -.094(**) 1.000 Correlation May a.m. light Spearman's rho .083(**) .157(**) 1.000 Correlation May noon light Spearman's rho -.057(*) .148(**) .315(**) 1.000 Correlation May p.m. light Spearman's rho -.065(*) .138(**) -.053 .168(**) 1.000 Correlation
Table 4. Correlations of environmental variables as measured in May, 2002. ** Correlation is significant at the 0.01 level (2-tailed). * Correlation is significant at the 0.05 level (2-tailed).
Population source had a significant influence on whether or not seedlings emerged from
the soil (LOGREG, Nagelkerke R2 = 0.021, p<0.009). At 86%, the Petersburg seedlings had a significantly (Pearson Chi-Square = 11.72, df=3, p<0.008) greater than expected rate of 16 emergence and those from the Central population which, at 74%, had a statistically lower than expected rate.
The seedlings took between nine and forty-two days to emerge from the soil, with a mean of twelve days. Emergence time did not differ between seed sources, but was affected by substrate type (ANOVA, df = 4, F = 6.308, p<0.001) (Figure 2). With a mean of 11.50 days, seedlings planted in the moss/crust substrate emerged faster than those on the sand (Tukey HSD, p<0.002) and fine organic matter (Tukey HSD, p<0.01) at 12.56 and 12.50 days respectively
(Figure 4).
1.16 AB ge r
e 1.14 m e
o 1.12 AB t A A ys 1.10 da of r
e 1.08 b B 1.06 num
og of 1.04 L 1.02 N = 216 284 157 40 17 sand fine om coniferous om moss/crust coarse om
Figure 2. Means plot with error bars for ANOVA of the log of number of days from planting to seedling emergence by planting substrate (om = organic matter).
Transplants survived at a higher rate than seedlings in both years of the study. In 2002,
86% of the transplants and 61% of the seedlings survived through June, while 55% of the 17 transplants and 30% of the seedlings were still alive in June of 2003 (Figure 3). For 2002,
Crosstabs test results indicated that transplants (n=384, 86%) had a higher than expected and seedlings (n=548, 61%) a lower than expected level of survival (Pearson Chi-Square = 84.70, df=1, p<0.001). For 2003, the transplants (n=247, 55%) again outsurvived the seedlings (n=265,
30%) (Pearson Chi-Square = 25.12, df=1, p<0.001).
100 2002 2003 90 80 70 d
e 60 t an l 50 p
% of 40 % Survival 30 20 10 0 384 247 548 265
seedlings transplants
Figure 3. Survival of seedlings and transplants through June of each year, as a percentage of the number
of genets planted in the field.
Of the seedlings that emerged, an increased number of days to emergence, herbivory, higher noon-time light levels in May and disturbance each reduced the probability of seedling survival through the first season (LOGREG, Nagelkerke R2 = 0.411) (Table 5).
18
B S.E. Wald df Sig. Herbivory -2.838 0.235 146.297 1 <0.001 LG10_Days to Emerge -5.494 1.149 22.854 1 <0.001 Disturbance -2.742 0.752 13.298 1 <0.001 Noon Light -1.503 0.414 13.200 1 <0.001 Constant 9.351 1.365 46.910 1 <0.001
Table 5. Logistic regression on seedling survival through June 2002.
Herbivory in 2002 and higher light levels for May noon and afternoon also reduced
chances of seedling survivorship through the second season (2003). Additionally, seedlings that
were larger in June of 2002 had a greater probability of survival through 2003, while seed
population source was also a factor in seedling survival (LOGREG, Nagelkerke R2 =0.321)
(Table 6). Seedlings from the Blowout (54%) and Piel (38%) populations had a greater than expected and those from Petersburg (34%) and Central (32%) had a lower than expected rate of survival (Pearson Chi-Square = 13.31, df=3, p<0.004) (Figure 4).
B S.E. Wald df Sig. June Plant Size 0.020 0.003 59.562 1 <0.001 Population 16.078 3 <0.002 Noon Light -1.097 0.308 12.673 1 <0.001 Afternoon Light -1.131 0.324 12.180 1 <0.001 Herbivory -1.425 0.450 10.015 1 <0.003 Constant -.367 0.467 0.618 1 <0.433
Table 6. Logistic regression on seedling survival from June 2002 to June 2003. 19
100 emergence 2002 2003 90 80 70
60 planted 50 seeds f 40 % o % Survival 30 20 10 0 173 129 66 216 162 70 83 65 46 242 192 83
piel central blowout petersburg
Figure 4. Seedling survival at three points in time by population as a percentage of the number of seeds planted in the field.
Through June of 2002, the probability of transplant survival increased with the increased size of the initial transplant and decreased with root zone disturbance and herbivory. The probability of survival also varied significantly by seed source (LOGREG, Nagelkerke R2 =
0.375) (Table 7). The Central (92%) and Petersburg (89%) populations had a higher than expected rate of survival, while the Piel (80%) and Blowout (76%) populations were below expectations (Pearson Chi-Square = 12.86, df=3, p<0.05) (Figure 5). As with the seedlings, larger plants in June of 2002 had increased odds of survival through the following year
(LOGREG, Nagelkerke R2 = 0.456) (Table 8). For plants that survived through 2003, there was a significant difference in the number of days to seedling emergence, the number of leaves in the initial transplant, and the number of leaves on seedlings and transplants in June 2002 (Table 9). 20
B S.E. Wald df Sig. Disturbance -2.786 0.360 59.941 1 <0.001 Herbivory -1.355 0.347 15.258 1 <0.001 Initial Transplant Size 0.002 0.001 11.749 1 <0.002 Population 8.315 3 <0.041 Constant 1.620 0.594 7.446 1 <0.007
Table 7. Logistic regression of survival of transplants through June 2002.
100 2002 2003 90 80 70
60 transplants
l 50 a 40 initi 30 % Survival % of 20 10 0 102 69 121 68 44 27 117 83 piel central blowout petersburg
Figure 5. Transplant survival through late June of each year by population, as a percentage of the number of plants planted in the field.
B S.E. Wald df Sig. 2002 Plant Size 0.002 0.000 91.226 1 <0.001 Constant -1.463 0.183 63.857 1 <0.001
Table 8. Logistic regression of the survival of transplants from June, 2002 to June, 2003.
21
Was the plant Days to Leaves at Leaves Leaves viable in June emerge planting in 2002 in 2003 of 2003?
11.63 * 2.88 ** 12.07 Yes (9 – 41) (1 – 5) (1 – 65)
Seedlings
12.44 * 2.29 ** No (9 – 42) (1 – 5)
10.13 ** 20.33 ** 66.87 Yes (5 – 24) (1 – 79) (1 – 221)
Transplants
9.21 ** 8.41 ** No (3 – 19) (1 – 39)
Table 9. For plants that had not been damaged by animals in the first season and had survived through the second season, the table shows the mean number of days for seedlings to emerge from soil and the mean number of leaves at different time-points for transplants and seedlings. Ranges are given in parentheses and significant differences are indicated with * (<0.05) and ** (<0.01).
As expected, the transplants were larger than the seedlings in both years (t-test, p<0.001
in each case). In addition, although some seedlings were much larger in June 2003 than the
transplants were at the start of the study , the initial transplants were significantly larger than the
2003 seedlings (Mann-Whitney U, mean rankTransplants = 385.19 mm, mean rankSeedlings = 313.88 mm, p <0.001).
Similar to survival through the first season, the size of the seedlings in late June of 2002 was significantly reduced by increased time of seedling emergence, and increased noon and afternoon light. There was an indication that seedling size was also affected by population source, but there was no effect of substrate on seedling size in 2002 (Table 10, Figures 6 & 7).
22
Sum of Source Squares df F Sig. Corrected Model 2.159 6 6.993 <0.001 Intercept 1846.796 1 35893.797 <0.001 Noon Light 0.635 1 12.343 <0.001 Afternoon Light 0.494 1 9.600 <0.003 LG10 Days to Emerge 0.629 1 12.230 <0.002 Population 0.400 3 2.594 <0.053 Error 25.211 490 Total 1874.166 497 Corrected Total 27.370 496
Table 10. GLM of log of "size" of seedlings in June, 2002. (df = 6, F = 6.993, p<0.001, Adj. R2= 0.068). Computed using alpha = 0.05.
With only one seedling alive in 2003, coniferous organic matter was removed from the substrate variable for variance analyses. Seedlings grew larger when 2002 seedlings were larger and soil pH was higher (Table 11).
Sum of Source Squares df F Sig. Corrected Model 8.581 9 6.027 <0.001 Intercept 1928.645 1 12190.610 <0.001 LG10 2002 Size of Seedling 5.957 1 37.652 <0.001 LG10 Soil pH 1.295 1 8.184 <0.006 Error 38.286 242 Total 1975.513 252 Corrected Total 46.867 251 Table 11. GLM of the log of "size" of seedlings in June, 2003. (df = 9, F = 6.027, p<0.001, Adj. R2= 0.153) Computed using alpha = 0.05.
Source population continued to be an important factor in 2003 (ANOVA, df = 3, F =
2.947, p< 0.034), with the seedlings from the Petersburg population growing significantly larger than those from Piel (Tukey HSD, p<0.030) (Figure 6). 23
1400 June, 2002 June, 2003 BC 1200 C
BC 1000
) B mm
( 800 mm
Size 600 g
400 Seedlin 200 A A A A
0 117 65 146 68 60 44 174 80 piel central blowout petersburg
Figure 6. Mean “size" (# of leaves x width of largest leaf) of seedlings by population source in 2002 and 2003. Sample size shown at bottom of bars with population name. Bars with the same letter above were not significantly different by Tukey HSD tests.
1400 June, 2002 June, 2003 1200
) 1000 mm ( 800 m m Size
g 600
400 Seedlin 200
0 143 63 212 113 111 65 25 16 3 1 sand moss/crust fine om coarse om coniferous om
Figure 7. Mean “size" (# of leaves x width of largest leaf) of seedlings by planting substrate in 2002 and 2003. There were no significant differences between groups in either year. Sample size shown at bottom of bar above substrate type (om = organic matter). 24
Transplants from different populations differed in size at planting (ANOVA, df=3,
F=13.271, p<0.001). The Petersburg plants were larger than those from Piel and Central (Tukey
HSD, p<0.001) and the plants from Blowout were larger than those from Piel (Tukey HSD,
p<0.017) (Figure 8).
Increased initial transplant size was the major factor creating larger 2002 plants,
accounting for almost 15% of the variation, while higher levels of light at noon had a negative effect (Table 12). Population differences in transplant size were still apparent in June of 2002
(ANOVA, df=3, F=12.296, p<0.001). The Petersburg plants were larger than the plants from
Blowout (Tukey HSD, p<0.029) and Central (Tukey HSD, p<0.01), and the plants from Piel were larger than those from Central (Tukey HSD, p<0.007) (Figure 8).
Source Sum of Squares df F Sig. Corrected Model 15270.833 9 8.892 <0.001 Intercept 84926.447 1 1493.188 <0.001 Noon Light 888.315 1 4.655 <0.033 Initial Transplant Size 8816.674 1 46.205 <0.001 Population 5228.294 3 9.133 <0.001 Error 51520.721 270 Total 351718.000 280 Corrected Total 66791.553 279
Table 12. GLM of square root of size of transplants in June, 2002. (df = 9, F = 8.892, p<0.001, Adj. R2= 0.203). Computed using alpha = 0.05.
The size of the transplants in late June of 2003 was primarily increased by an increased
size of the plants the previous year, which accounted for over 27% of the variation, but was also
positively influenced by larger initial transplant and increased noon light (Table 13). Although
population was not found to be a significant factor in transplant size in 2003, the plants from the 25
Petersburg population were significantly (Tukey HSD, p<0.014) larger than those from the
Central population (ANOVA, df=3, F=3.296, p<0.023) (Figure 8).
Sum of Source Squares df F Sig. Corrected Model 56836.412 7 13.483 <0.001 Intercept 899336.332 1 1493.397 <0.001 Square Root 2002 Plant Size 39567.773 1 65.704 <0.001 Square Root Initial Transplant Size 6915.890 1 11.484 <0.002 Noon Light 4007.863 1 6.655 <0.012 Error 104784.256 174 Total 1060957.000 182 Corrected Total 161620.668 181
Table 13. GLM of square root of size of transplants in late June, 2003. (df = 7, F = 13.483, p<0.001, Adj. R2 = 0.326). Computed using alpha = 0.05.
8000 A p r i l , 20 02 J u n e , 20 02 J u n e , 20 03 GI
7000 GHI
) GHI 6000 mm ( GH 5000
4000 mm lant Size p 3000 DF E DE F Trans 2000 A AB BC C 1000
0 127 75 52 132 93 52 58 32 20 131 80 58 piel central blowout petersburg
Figure 8. Mean “size” (# of leaves x width of largest leaf) of transplants at three points in time, by population. Sample size shown at the bottom of bars above population name. Bars with the same letter above were not significantly different by Tukey HSD tests.
26
8000 April, 2002 June, 2002 June, 2003 7000
) 6000 mm ( 5000
m 4000 m lant Size
p 3000
2000 Trans
1000
0 190 119 68 140 95 69 69 36 24 40 24 19 9 6 2
sand moss/crust fine om coarse om coniferous om
Figure 9. Mean “size” (# of leaves x width of largest leaf) of transplants, at three points in time. by planting substrate. There were no significant differences between groups at any of the time points. Sample size shown at the bottom of bars with substrate type (om = organic matter).
In each of the two years of the study, more of the transplants flowered than did the seedlings. In 2002, no seedlings flowered, while 19% (n = 75) of the surviving transplants did.
In 2003, significantly more transplants (25%, n = 62) had flowered compared to the surviving seedlings (1%, n = 3) (Pearson Chi-Square=118.347, df=1, p>0 .001).
The size of the transplant in June of 2002 significantly increased the chances of flowering in that year (LOGREG, Nagelkerke R2 = 0.178) (Table 14). Not enough seedlings flowered in
2003 to allow for logistic regression analysis of the factors that might influence their probability of flowering. In 2003, the chance of a transplant flowering was significantly increased when plants grew more from planting to the second year but slightly decreased when the transplants were larger at planting (LOGREG, Nagelkerke R2 = 0.425) (Table 15). 27
B S.E. Wald df Sig. 2002 Transplant Size 0.001 0.000 32.158 1 <0.001 Constant -2.575 0.281 83.796 1 0.000
Table 14. Logistic regression on the probability of flowering in 2002.
B S.E. Wald df Sig. Growth From Initial to 0.000 0.000 38.252 1 <0.001 2003 Transplant Size Initial Transplant Size -.002 0.001 6.648 1 <0.011 Constant -1.923 0.600 10.268 1 <0.001
Table 15. Logistic regression on the probability of flowering in 2003.
In 2002, 734 (18.82/plant) seeds were collected from the transplants that had flowered.
In 2003, 3544 (75.40/plant) seeds were collected from transplants and 96 (48/plant) seeds were collected from seedlings. As with flowering, the size of the plant in June was the only factor found to significantly influence the probability that plants that had flowered would produce seed in the first year (LOGREG, Nagelkerke R2 = 0.238) (Table 16). Similarly, the difference in size from planting to 2003 significantly increased the chance of seed set in the plants that had flowered in 2003 (LOGREG, Nagelkerke R2 = 0.310) (Table 17).
B S.E. Wald df Sig. 2002 Transplant Size 0.001 .000 18.440 1 <0.001 Constant -2.973 .280 113.022 1 <0.001
Table 16. Logistic regression on the probability of seed set in 2002.
B S.E. Wald df Sig. Growth From Initial to 2003 0.000 .000 7.743 1 <0.006 Transplant Size Constant -1.708 .981 3.031 1 <0.083
Table 17. Logistic regression on the probability of seeding in 2003. 28
Although no factors were found to predict the amount of seeds produced by the plants that had flowered in 2002, population had a significant effect on the number of seeds produced in
2003 (Table 18). With a mean of 144 seeds per plant, the Petersburg population plants produced significantly more seeds than those from the Piel and Central populations at 42 and 52 seeds per plant respectively (ANOVA, F=4.872, df=3, p<0.006) (Figure 10).
Sum of Source Squares df F Sig. Corrected Model 2.104 3 3.457 <0.027 Intercept 115.887 1 571.110 <0.001 POPULATION 2.104 3 3.457 <0.027 Error 7.305 36 Total 125.296 40 Corrected Total 9.409 39
Table 18. GLM of the log of number of seeds produced in second season (2003). (df = 3, F = 3.457, p<0.027, adj. R2 = 0.159). Computed using alpha = 0.05.
200 C
180 transplants 2002 transplants 2003 seedlings 2003
160
140 120
100 BC 80 B B 60 Number of Seeds Set 40 A A A A 20 0 10 15 10 14 1 2 5 1 17 13 piel central blowout petersburg
Figure 10. Mean number of seeds produced by transplants in 2002 and 2003 and by seedlings in 2003 as shown by source population. Numbers of plants that produced seeds are shown at the bottom of the bars. Bars with the same letter above were not significantly different by Tukey HSD tests. 29
DISCUSSION
Previous research on L. perennis has provided information important in understanding its
growth, preferred habitats, and relationships to insects of concern. Grigore and Tramer (1996)
showed that established L. perennis plants grew larger and had a higher flower production in
sites that had been burned during the previous dormant season. They also determined that seeds
planted in a recently burned site fared better than those planted in similar habitats that had not
been recently burned, theorizing that this may be due to the release of nutrients by the materials
burned or the earlier warming of the exposed soil in the spring. Boyonoski (1992) and Kelly
(1998), in unpublished Master’s theses, found that L. perennis seedlings grow best when planted
in soils with a pH within a narrow range of 4.8 – 5.2. This is substantiated by another
unpublished Master’s thesis study by Greenfield (1997), which showed that L. perennis plants
had the greatest vigor in soils with a pH range of 4.6 – 5.5. The study by Kelly (1998) indicated
that while seeds planted in bare soils with no canopy cover produced larger seedlings, the rate of
seedling survivorship was reduced. Grundel and others (Grundel et al. 1998b) found that larvae
of the Karner blue butterfly prefer to eat shade-grown L. perennis leaves, even though the
majority of the flowering plants will be found in sunny areas.
Some researchers have examined the relative success of restoration of rare plant
populations from seeds and transplants in prairies and savannas. Morgan (1997) suggested that a study species in Australia was more successful in its establishment through the use of transplants than it was through seeding. A study on Lupinus sulphureus ssp. kinkaidii in Oregon, found that in the first two years, greenhouse grown transplants had a higher rate of survival than the field sown seeds (Kaye and Cramer 2003). 30
The results of this study on L. perennis also indicate that greenhouse grown transplants
fared better during the first two years than the plants that grew from seeds that were sown on
site. By the end of the study, the transplants had a higher rate of survival, were significantly
larger, had flowered more, and had produced almost fifty times more seed than the seedlings.
Both herbivory of the above ground portions and disturbance of the below ground parts
of the seedlings and transplants had a significantly detrimental effect on the probability of
survival. The transplants had primarily been nipped at the leaf petioles but sometimes the stems
were bit through just above ground level and left on the ground. The fresh tracks around the
damaged plants indicated that the plants were being browsed by deer. The seedlings primarily
showed evidence of caterpillar damage. Most root zone disturbances came as a result of below
ground tunneling by moles, while other disturbances occurred when transplants were dug from
the ground, possibly by either skunks or raccoons. The severity of the deer browsing may have
been due to the transplants being the only green plants in early May in the relatively open study site. Browsing seemed to occur more frequently within a few meters of a deer trail that crossed the site and in more exposed planting points such as sandy ridge tops. Planting the transplants further from the trail might have reduced the mortality rate. Both forms of belowground disturbance seemed to be randomly distributed throughout the study site.
Source population, substrate, and light proved to be important factors influencing L. perennis seedling establishment. The probability of a seedling emerging from the soil differed by population source, with seeds from the Central site showing the lowest rate of emergence as well as the lowest rate of survival through 2003. Seeds planted in the moss/crust substrate emerged more rapidly than those planted in areas of sand or fine organic matter soil cover. A more rapid seedling emergence led to a greater probability of survival and larger seedlings in 2002. In a 31
meta-analysis of 55 studies of seedling emergence rates, early emergence has been shown to be
highly beneficial to seedling growth and potential fecundity (Verdu and Traveset 2005). In L.
perennis, larger seedlings in 2002 had an increased probability of survival through 2003 and led
to larger plants as well.
Increased light levels during the noon and afternoon periods had detrimental effects on
seedling survival and size in 2002, with higher noon light also decreasing seedling survival
through 2003. This result is consistent with findings of Cartwright (1997) and Kelly (1998).
Although light levels did not significantly affect transplant survival, high noon light levels were
a positive influence on transplant size in 2003. This should be taken into account when
attempting to introduce L. perennis to a restoration site or to augment existing populations.
Seedlings may have a higher initial rate of survival with some protection from the sun during the hotter parts of the day; however, once established, the plants may grow more rapidly with increased mid-day light. As the availability of L. perennis seed can be limited, it would seem best to have higher rates of recruitment than a slightly more rapid growth rate of the survivors.
As L. perennis plants growing in moderately shaded areas have been shown to have a higher rate of ovipositing by the Karner blue butterfly (Grundel, et. al. 1998b), it would be an additional benefit to planting in locations with protection from mid to late-day sunlight.
As with previous studies (Boyonoski 1992, Cartwright 1997, Kelly 1998), in 2003
relatively higher soil pH levels were correlated with increased seedling size. It should be noted
that there was a relatively narrow pH range of 3.44 – 5.0 at the study site. Similar to the study by
Cartwright (1997), this was also the only analysis in which any of the tested soil characteristics
(moisture, pH, and phosphorus) had a significant effect on either seedlings or transplants. In this
study, differences in soil moisture percentages may have been masked by the higher than average 32 rainfall in the first month of the study (NWS 2007). The absence of a significant influence for soil phosphorus may have been due to the acidic nature of the soils throughout the study site. At pH levels below 5.0, phosphorus can be bound by aluminum or iron in the soil and may not have been readily available to the plants (PSU 2007).
Transplant survival in 2002 was increased by an increased size at planting. The increased initial size also increased the size of the transplants in June of 2002. Although population also had an effect on 2002 plant size, there was a significant hierarchical change in source population ranking from the initial planting. The plants from the Piel population, which at planting, had been significantly smaller than both the Petersburg and Blowout plants, became the second largest population two months later. As with the seedlings, larger transplants in 2002 led to significantly larger plants in 2003. Although there was a statistically significant difference between the mean number of leaves at planting on transplants that survived through 2003 and mean (M=10.13) number of leaves at planting on transplants that didn’t(M=9.21), the ranges of these two groupings are large and almost completely overlap, likely due large sample sizes (see
Table 9). This overlap makes it difficult, practically speaking, to suggest an optimum leaf number that would predict survival.
In general, throughout the study, plant size was influential in the size of the plants at later time points. In both seedlings and transplants, the population source also had an influence on plant size. The transplants from the Petersburg population grew to be consistently larger, followed by those from the Piel, Blowout and Central populations. With the seedlings however, the Blowout plants were slightly larger than the Petersburg plants, while the Piel population that had fared well as transplants ranked last in seedling growth. It is not known whether the performance differences between population groups were due to local adaptation, differences in 33
genetic diversity, or maternal effects. Many convincing arguments have been made both for and
against the concept of local adaptation (McKay et. al. 2005, Mantalvo et. al. 1997). In this study,
it may be that some of the populations have a history of inbreeding, reducing population fitness.
It may also be that resources allocated to the seeds by the mother plants varied by source
population due to environmental limitations at the maternal site. Halpern (2005) found that increased L. perennis seed size had positive effects on germination rate and timing as well as seedling survival and increased plant size over a two year study. Unfortunately, the study did not report correlations between maternal plant vigor and size of the seeds produced.
Plant size was also a significant influence on flowering and fruiting. In 2002, an increase
in plant size increased the probability of flowering and of setting seed. In 2003, increased
growth from transplanting to the second season increased the probability of flowering and setting
seed. The seed production of the transplants far exceeded that of the seedlings, 3628 to 96.
The decision as to whether to use transplants or seeds as a means of establishing a
population of L. perennis at a savanna restoration site seems to be an easy one if only the
number, size, flowering, and seed production of the plants is taken into consideration. The
benefits of using transplants must be weighed against the costs, in labor, materials, and facilities.
As noted earlier, there was approximately 9.5 times the amount of labor involved in the
production and planting of transplants than the planting of seeds in the field. This might not be
of much consideration if done with volunteer labor, but could be of significant cost if the
growing or planting are performed by paid help. Additionally, one should factor in the cost of the pots, trays and soil as well as the cost of the facilities involved in greenhouse production.
Kaye and Cramer (2003) found a higher monetary cost per leaf and seed produced by greenhouse
grown Kinkaid’s lupine compared to the cost of seeding. However, they also calculated a cost in 34
seed resources, finding that it took more seeds to produce leaves and flowers on seedlings than
for leaves and flowers to be produced on transplants. The costs of the use of seed resources should also be taken into consideration when seed supplies are limited.
The higher monetary cost of using transplants could be offset by the earlier development
of mature plants. Flowering in the first year could be a boon to public relations, especially in a
restoration project that, to the uneducated eye, looks more like destruction. The earlier
production of seeds would also accelerate the establishment of an even larger population, either
through natural dissemination of seeds or collection and purposeful planting. In situations where
time is not critical however, the establishment of a population through direct seeding on site
would be much less expensive. In 2003, the second year seedlings were approaching the size the
transplants had been at planting and produced more seeds per plant in their second season than
the transplants did in 2002 after one field season. Perhaps, with a full season of growth in 2004,
they would be able to flower and seed as well as the transplants did in 2003, effectively putting
them only a year behind the development of the transplants.
The results of this study are limited to the time when and place where it was conducted.
Although heterogeneous in microsite variation of abiotic factors, it was only one site in
northwestern Ohio. In addition, during the first month of the study the plants may have unfairly
benefited from above average rainfall and below average temperatures. Had it been a hotter or
drier month, the levels of emergence and survivorship might not have been as high as they were,
possibly further increasing the relative difference in survivorship of transplants and seeds.
The establishment of large populations of L. perennis is critical to the support or re-
introduction of the federally endangered Karner blue butterfly (Tolson 1998, WDNR 2001).
Regeneration of prairie and savanna habitats by mechanical thinning, mowing, and controlled 35
burning can in many cases the reopen the canopy of woody vegetation enough for remnant L.
perennis to spread and reestablish a large population (Abella 2001). However, in sites where L.
perennis has been extirpated or the populations are very small, new colonies of plants may have to be reintroduced through the planting of seeds or nursery grown plants. The results this study should benefit land stewards in their deciding on a plan to accomplish this goal.
36
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