Rebecca W. Dolan

Living More Than Just Enough for the City: Persistence of High-Quality Vegetation in Natural Areas in an Urban Setting

Rebecca W. Dolan et al. — Tue, 04 Oct 2011 06:05:17 PDT

Urban environments pose special challenges to flora, including altered disturbance regimes, habitat fragmentation, and increased opportunity for invasion by non-native species. In addition, urban natural area represents most people’s contact with nature, given the majority of the world’s population currently live in cities. We used coefficients of conservatism (C-values), a system that ranks species based on perceived fidelity to remnant native plant communities that retain ecological integrity, to quantify habitat quality of 14 sites covering 850 ha within the city of Indianapolis, Indiana, in the Midwestern United States. All sites contained significant natural area and were inventoried via intensive complete censuses throughout one or two growing seasons within the last 15 years. Mean C-values for five sites were high, especially when compared to values reported for the highest quality preserves in central Indiana. However, for most sites the difference in mean C-value with and without non-natives was rather high, meaning that natural quality is likely to have been compromised by the presence of non-natives. Sites receiving the highest levels of stewardship and those with the least public access via trails had the highest mean native C-values. A total of 34 invasive non-native species were found across all 14 sites. Most were woody species. Mean C-value over all sites was significantly negatively correlated with the number of non-natives present, especially those considered invasive. These results demonstrate for the Indianapolis area, and likely other urbanized Midwestern cities, remnant natural areas can retain high ecological value, especially if they receive regular environmental stewardship.

Documenting effects of urbanization on flora using herbarium records

Rebecca W. Dolan et al. — Mon, 09 May 2011 09:46:09 PDT

1. As human populations increasingly live in cities, urban floras and the ecosystem services they provide are under increasing threat. Understanding the effects of urbanization on plants can help to predict future changes and identify ways to preserve biological diversity. Relatively few studies document changes through time in the flora of a focal region and those that do primarily address European floras. They often rely on contemporary spatial gradient studies as surrogates for changes with time.

2. We compare historical species records (prior to 1940) with the current flora for Marion County, Indiana, USA, home to Indianapolis, the 13th largest city in the United States. Specimens from the Friesner Herbarium of Butler University and other vouchered records for the county provided the basis for historical records. Current records are derived from inventories of 16 sites conducted by Herbarium staff and other botanists over the past 15 years.

3. Physiognomic group, wetland classification and nativity (native vs. non-native) were determined for each species. Fidelity to high-quality habitat was quantified using coefficients of conservatism (C-values).

4. The last 70 years have seen a significant turnover in species presence, most notably a decrease in native plant species number (2.4 per year) and quality, with an accompanying increase in non-native plants of 1.4 per year. Loss of species has been non-random, with a disproportionate number of high-quality wetland plants lost. The signature of past land use can be seen in physiognomic changes in the composition of the flora that reflect the shift from agriculture to urban/suburban land use.

5. Many invasive non-native shrubs now present have escaped from cultivation, highlighting the combined threats of habitat conversion and human plant preference to native flora in cities. These invasives likely present the greatest threat to remaining biodiversity.

6. Synthesis. This study demonstrates the value well-documented historical records, such as those housed in herbaria, can have in addressing current ecological issues.

Floristic Investigation of Crooked Creek Community of Juan Solomon Park, Indianapolis Indiana

Raelene M. Crandall et al. — Tue, 14 Sep 2010 07:28:11 PDT

The protection of plant resources in urban areas is a growing conservation concern. InveI1lory activities that document species presence and stewardship plans that protect and enhance these areas are needed. The results of a botanical inventory of the Crooked Creek Community Juan Solomon Park in Indianapolis, Indiana, are reported in this paper. The 46-acre park contains three distinct habitats, supporting a wide variety of plants. One hundred seventy-nine vascular plant species from 64 families were identified, including 53 (29.6%) non-native species that are naturalizing within the park. Despite its high percentage of alien species and urban setting, the park is an important natural area. The flora's coefficient of conservatism was 54.1. Several exotic, invasive species (most notably garlic mustard, annul' bush honeysuckle, and wintercreeper) pose potential future threats to the park's natural flora, and management efforts should be focused on their removal.

Hypericum cumulicola demography in unoccupied and occupied Florida scrub patches with different time‐since‐fire

Pedro F. Quintana‐Ascencio et al. — Thu, 02 Sep 2010 12:20:53 PDT

1 Metapopulation models predict that unoccupied, but suitable, patches will exist for species subject to extinction and colonization dynamics. We compared the demographic responses of Hypericum cumulicola, a rare herbaceous species almost entirely restricted to Florida rosemary scrub, when transplanted to occupied or unoccupied patches. 2 Seedlings were transplanted and seeds buried into Florida rosemary scrub patches differing in time since last fire, and in the presence or absence of H. cumulicola. We used a replicated, factorial design to place the transplants and seeds in the field, and monitored their performance for 18 months. 3 Neither time‐since‐fire nor prior H. cumulicola site occupancy affected survival of transplants. Only time‐since‐fire affected growth. Time‐since‐fire, H. cumulicola occupancy, and their interaction affected reproductive effort, but these effects were not consistent between years. 4 Flowering and seed production led to subsequent seedling recruitment near transplants, mainly in recently burned sites. Genetic screening of transplants and seedlings showed that transplants in occupied sites could have crossed with nearby resident plants, but that offspring in sites previously unoccupied were likely to have been parented only by nearby transplants. 5 Seeds buried, and later exhumed, germinated after 1 or 2 years of burial, demonstrating a persistent soil seed bank from which populations could recover after fire. Neither time‐since‐fire nor H. cumulicola occupancy affected seed dormancy or germination. 6 Similar demography in unoccupied and occupied patches suggests that the patchy pattern of site occupancy by H. cumulicola is probably due to limited dispersal and periodic extinction, especially associated with long fire‐free intervals. Conservation measures need to protect unoccupied patches to allow metapopulation dynamics and persistence.

Note: Link is to the article in a subscription database available to users affiliated with Butler University. Appropriate login information will be required for access. Users not affiliated with Butler University should contact their local librarian for assistance in locating a copy of this article.

Population dynamics of Ludwigia leptocarpa (Onagraceae) and some factors affecting size hierarchies in a natural population

Rebecca W. Dolan et al. — Thu, 02 Sep 2010 12:16:43 PDT

(1) Germination cohorts of Ludwigia leptocarpa, a semi aquatic annual plant were marked in the field at time of establishment and followed through the 1981 and 1982 growing seasons at a site in southern South Carolina. (2) Data from each cohort were pooled to determine demographic characteristics of the population as a whole, then analysed separately to determine the effect of time of germination on survivorship, relative growth rate, and adult size. (3) Changes in numbers of L leptocarpa fit a Deevey Type II survivorship curve. This and other characteristics of the species classify it as 'r-selected'. Aspects of the life history may reflect a 'bet-hedging' strategem that ensures establishment. (4) Differences in the time of germination are not responsible for differences in adult size, even when early germinating plants have as many as 35 days more for growth than late germmators. This, and the fact that differences occur even within single cohorts, implies that factors other than time of germination must influence plant size.

Effects of a Prescribed Burn on Tree- and Herb-layer Vegetation in a Post Oak (Quercus Stellata) Dominated Flatwoods.

Rebecca W. Dolan — Wed, 30 Jun 2010 11:29:16 PDT

Post oak flatwoods are an unusual plant community type dominated by even-aged and uniformly sized post oaks (Quercus stellata) growing along level terraces of the Ohio River. Historical evidence exists that fire may play a role in the maintenance of the open canopy and poorly-developed understory characteristic of this community type (Dolan and Menges. 1989). The results of summer vegetation surveys taken yearly from 1989 to 1992 in a post oak flatwoods in southwestern Indiana that was subjected to a prescribed bum in the spring of 1989 are reported in this paper. The objective of the study was to determine the effects of the burn on tree-and herb-layer vegetation. The fire killed or top-killed more than half the trees but did not markedly shift the rank order of species importance values. Mortality was greatest among small tree species, such as winged elm and shingle-bark oak, and least among post oak. Composition of the herb-layer did not change greatly following the fire. but several new species were found that did not occur in unburned control plots. The results indicate that fire contributes to the unusual species composition and community structure of post oak flatwoods.

The Royal Catchfly (Silene Regia; Caryophyllaceae) In Indiana

Rebecca W. Dolan — Wed, 30 Jun 2010 11:29:08 PDT

Botanist Thomas Nuttall called the royal catchfly, Silene regia, "one of the most splendid species in existence." This red-flowered, hummingbird-pollinated member of the Caryophyllaceae is a perennial herb of prairies and glades. Because of the conversion of much of its former habitat to agriculture, the royal catchfly is considered threatened in Indiana. The species' historical and present-day distribution in the State, documenting the current status of all known locations, including population sizes and co-occurring species, are reported in this paper. Only 8 of the documented 23 historical locations still support the plant. No populations occur in dedicated nature preserves or other protected areas. However, the Division of Nature Preserves of the Indiana Department of Natural Resources does manage the site containing the largest and most genetically variable population in the State. Active management to promote prairie vegetation at the site may be the key to maintaining this high-quality population.

A Complete Index to the Butler University Botanical Studies, a Journal of Original Research Published by Butler University 1929-1964

Rebecca W. Dolan — Wed, 30 Jun 2010 11:29:07 PDT

For 35 years, the Botany Department of Butler University published a journal of research conducted by Butler faculty, students. and other Indiana botanists. Many of the papers contain valuable historical studies. especially floristic surveys that document Indiana's vegetation in past decades. This article presents a complete index for the journal. arranged both chronologically and alphabetically. Reprints of articles are still available.

Capturing Genetic Variation during Ecological Restorations: An Example from Kankakee Sands in Indiana

Rebecca W. Dolan et al. — Tue, 27 Apr 2010 12:28:37 PDT

Genetic variation in populations, both natural and restored, is usually considered crucial for response to short term environmental stresses and for long term evolutionary change. To have the best chance of successful long-term survival, restored populations should reflect the extant variation found in remnants, but restored sites may suffer from genetic bottlenecks as a result of founder effects. Kankakee Sands is a large-scale restoration being conducted by The Nature Conservancy (TNC) in northwestern Indiana. Our goal was to test for loss of genetic variation in restored plant populations by comparing them with TNC’s seed source nursery and with local remnant populations that were the source of nursery seed and of the first few restored sites. Allozyme analysis of Baptisia leucantha, Asclepias incarnata, Coreopsis tripteris, and Zizia aurea showed low levels of allozyme diversity within all species and reductions in polymorphism, alleles per locus, and expected heterozygosity between remnants and restorations for all species except A. incarnata. Almost all lost alleles were rare; restored populations contained almost 90% of alleles at polymorphic loci that occurred in remnants at frequencies greater than one percent. Allele frequencies for most loci did not differ between remnants and restored sites. Most species showed significant allele frequency differentiation among remnant populations and among restored sites. Our results indicate that seed collection techniques used at Kankakee Sands captured the great majority of allozyme variation present in seed source remnant populations.

Comparative genetics of seven plants endemic to Florida’s Lake Wales Ridge

Eric S. Menges et al. — Thu, 08 Apr 2010 05:31:53 PDT

Here we submit that mathematical tools used in population viability analysis can be used in conjunction with floristic and faunistic surveys to predict changes in biogeographic range. We illustrate our point by summarizing the results of a demographic study of Lobelia boykinii. In this study we used deterministic and stochastic matrix models to estimate the growth rate and to predict the time to extinction for three populations growing in the Carolina bays. The stochastic model better discriminated among the fates of the three populations. It predicted extinction for two populations in the next 25 years but no extinction of the third population for at least 50 years. Probability of extinction is likely correlated with hydrologic regime and fire frequency of the bay in which a population is found. The stochastic model could be combined with information about the geographic distribution of L. boykinii habitats to predict short-term biogeographic change.

The Clute holotypes and the herbarium of Willard Nelson Clute in the Friesner Herbarium of Butler University

Rebecca W. Dolan — Mon, 05 Apr 2010 05:55:26 PDT

The herbarium of Willard Nelson Clute is housed in the Friesner Herbarium (BUT). Clute, co-founder of the American Fern Society, was a staff member at Butler University in the 1920's and 30's. His collection of ferns and fern allies from the tum of the century is significant for its selected regional coverage and for type specimens of taxa described by Clute and other fern specialists of the day.

Genetic Variation in Past and Current Landscapes: Conservation Implications Based on Six Endemic Florida Scrub Plants

Eric S. Menges et al. — Tue, 30 Mar 2010 06:56:17 PDT

If genetic variation is often positively correlated with population sizes and the presence of nearby populations and suitable habitats, landscape proxies could inform conservation decisions without genetic analyses. For six Florida scrub endemic plants (Dicerandra frutescens, Eryngium cuneifolium, Hypericum cumulicola, Liatris ohlingerae, Nolina brittoniana, and Warea carteri), we relate two measures of genetic variation, expected heterozygosity and alleles per polymorphic locus (APL), to population size and landscape variables. Presettlement areas were estimated based on soil preferences and GIS soils maps. Four species showed no genetic patterns related to population or landscape factors. The other two species showed significant but inconsistent patterns. For Liatris ohlingerae, APL was negatively related to population density and weakly, positively related to remaining presettlement habitat within 32 km. For Nolina brittoniana, APL increased with population size. The rather weak effects of population area/size and both past and current landscape structures suggest that genetic variation needs to be directly measured and not inferred for conservation planning.

The rare, serpentine endemic Streptanthus morrisonii (Brassicaceae) species complex, revisited using isozyme analysis

Rebecca W. Dolan — Mon, 29 Mar 2010 07:41:39 PDT

The Streptanthus morrisonii (Brassicaceae) complex is a group of six narrowly-distributed obligate serpentine endemic taxa whose habitat is threatened by geothermal development. Isozyme analysis of this little-studied complex supports the delineation of two species, S. morrisonii and S. brachiatus, but is at odds with the treatment of two subspecies based on morphology. These results may be influenced by small sample sizes but genetic studies of other Streptanthus taxa have shown patterns of relatedness that often transgress subspecies boundaries based on morphology. The present study further shows that members of the S. morrisonii complex share high genetic identity values (mean = 0.87) and are not genetically depauperate (mean value for percent of loci polymorphic = 37%, average number of alleles per locus = 1.48, and average heterozygosity per locus = 0.137). Preservation of their serpentine outcrop habitat is essential to the survival of these plants.

Population genetic structure in Nolina brittoniana, a plant endemic to the central ridges of Florida

Rebecca W. Dolan et al. — Mon, 22 Mar 2010 06:47:15 PDT

olina brittoniana is endemic to the central ridges of peninsular Florida. Its scrub and sandhill habitats have suffered extensive anthropogenic modification. Analysis of isozymes from populations throughout its range revealed less genetic variation than generally reported for endemic plants. Populations were well differentiated, with significant lines in allele frequency along the north-south axis of distribution. Pair-wise F-statistics calculated at four levels of population geographic substructure revealed that current and inferred historical habitat patches had similar genetic structure. We found no evidence of recent bottlenecks or changes in genetic structure due to habitat loss and fragmentation, consistent with populations having always been small, isolated and low density. Our data support preservation of populations from throughout the species' range to meet conservation objectives.

The Distribution of Fox Squirrel (Sciurus niger) Leaf Nests within Forest Fragments in Central Indiana

Carmen M. Salsbury et al. — Thu, 18 Mar 2010 11:41:28 PDT

We examined the abundance and placement of leaf nests by fox squirrels in six urban woodlots in central Indiana ranging in size from 1.06 to 8.28 ha. Four of the woodlots were disturbed, or subject to extensive human impact, whereas the remaining two were nature preserves. We counted all leaf nests present in each woodlot and recorded nest tree characteristics. We then conducted a quantitative vegetation analysis of trees present and estimated percentages of herbaceous and shrub cover along a minimum of two 100 m transects at each site. Fox squirrels showed a preference to build nests in certain species of trees. However, preference for nest tree species was not consistent across sites. Fox squirrels preferred to build nests in large trees with vines in the canopy at all sites. Characteristics of nests and nest trees did not differ among sites, but nest density was greater in the disturbed sites compared to the nature preserve sites. The nature preserve sites differed from the disturbed sites only with regard to the amount of shrub and herbaceous cover; shrub cover was greater and herbaceous cover was less at the disturbed sites. Results of this study suggest that fox squirrels are flexible with regard to nest tree species used and that the choice of a nest tree is dependent, in part, on tree size and the presence of vines. Further, a higher density of leaf nests in disturbed woodlots suggests that habitat disturbance and fragmentation due to urbanization may not have detrimental effects on the abundance and persistence of fox squirrels.

Taxonomy of Streptanthus sect. Biennes, the Streptanthus morrisonii complex

Rebecca W. Dolan et al. — Thu, 18 Mar 2010 11:21:00 PDT

The Streptanthus morrisonii complex is a six-taxon group of closely related serpentine rock outcrop endemics from Lake, Napa, and Sonoma counties of California, USA. Two new subspecies (S. morrisonii subsp. kruckebergii and S. brachia/us subsp. hoffmanii) from Lake County, California, are described. The relationship of these taxa to others in the section is reviewed and descriptions and a key are provided.

Vegetation and environment in an adjacent post oak flatwoods and barrens in Indiana

Rebecca W. Dolan et al. — Thu, 18 Mar 2010 11:20:36 PDT

To compare adjacent post oak flatwoods and barrens communities in south-western Indiana, we used vegetational, environmental and fire history data in multivariate analyses. Barrens had greater dominance by post oak and lower tree species richness, but variation in tree species composition was not strongly related to soil moisture, litter depth or other environmental gradients measured. Tree growth has been slow and variable, with little difference between the barrens and flatwoods. Barrens and flatwoods differ in herb species composition, but with considerable overlap. In the barrens, herbaceous vegetation composition was correlated with tree basal area, litter depth and soil moisture; in the flatwoods, it was correlated with soil moisture and microelevation. The barrens and flatwoods differed only slightly but significantly in environment: barrens soils were drier in June 1986 than flatwoods soils. Data from fire-scarred trees show no clear evidence of differences in frequency or extent of fire between the flatwoods and barrens. Multistemmed post oaks in the barrens indicate that past cutting may have contributed to these openings within the closed canopy flatwoods matrix.

The effects of seed size and maternal origin on the distribution of individual plant size in Ludwigia leptocarpa (Onagraceae)

Rebecca W. Dolan — Thu, 04 Mar 2010 07:13:35 PST

Seed size is normally distributed for many annual species, while mature plant size is frequently positively skewed. A study was conducted to determine the influence of seed size and the role of genetic differences in determining relative seedling size for Ludwigia leptocarpa. Seed size had a significant effect on percentage germination and time of seed germination but no effect on dry weight or leaf area of seedlings. Seed size and spacing had a significant effect on seedling dry weight for plants grown under competition, while relative day of emergence had no effect. Familial (genetic) differences were found in average seed weight between maternal plants, but not in average number of days to germination, average weight of seeds which germinated, or shoot dry weight. It is concluded that neither seed size alone nor genetic differences between plants are directly responsible for the development of size hierarchies in Ludwigia leptocarpa populations. Large seed size does convey an advantage in growth when plants from seeds of differing initial size interact.

Patterns of isozyme variation in relation to population size, isolation, and phytogeographic history in royal catchfly

Rebecca W. Dolan — Tue, 02 Mar 2010 10:23:28 PST

The distribution of genetic variation within and among plant populations is influenced by both contemporary and historical factors. I used isozyme analysis of band phenotypes to examine genetic structure in the rare prairie forb Silene regia. Relationships between current-day population size, isolation, and phenotypic variation were assessed for 18 populations in two regions with differing postglacial history. Western populations from unglaciated southern Missouri and Arkansas were more genetically diverse based on the Shannon-Weaver index (H) and a polymorphic index than were more eastern populations. These differences may be due to loss of variation with repeated founding of new populations in previously glaciated sites in Indiana and Ohio. Within the western region, population size was not significantly correlated with genetic variation. In the east, size was correlated with Shannon-Weaver diversity. There was no relationship between variation and isolation in either region, but eastern populations were slightly more differentiated. Greater among-population differentiation and the demonstrated connection between population size and variation in the eastern sites may reflect lower levels of interpopulation gene flow in the fragmented remnant prairies of Indiana and Ohio.

Conservation implications of genetic variation in three rare species endemic to Florida rosemary scrub

Rebecca W. Dolan et al. — Tue, 02 Mar 2010 09:54:29 PST

Habitat conversion and fire suppression during the last 50 yr have greatly reduced and altered Florida scrub vegetation, resulting in threats to the persistence of its unique flora. As part of a larger conservation project, we investigated patterns of isozyme variation in three rare perennial scrub plants with overlapping ranges endemic to Florida rosemary scrub on the Lake Wales Ridge. All three species have low levels of genetic variation, comparable to or lower than those generally reported for rare plants with restricted geographic ranges. Liatris ohlingerae has more than twice the expected heterozygosity of the other two species, with little population differentiation. In contrast, Hypericum cumulicola has highly differentiated populations with little apparent interpopulation gene flow and heterozygote deficiencies indicative of inbreeding. Eryngium cuneifolium, the species with the narrowest range and fewest populations, has intermediate values for genetic parameters. Although the three species have narrow and overlapping geographic ranges and similar habitat specificity, we discuss how optimal conservation of each species differs.