Plant Ecology Program

Venus, FL, United States

Plant Ecology Program

Venus, FL, United States
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King R.A.,Plant Ecology Program | King R.A.,University of Minnesota | Menges E.S.,Plant Ecology Program
South African Journal of Botany | Year: 2017

Ecological disturbances in ecosystems are often essential for the continued success of many species, acting to increase resource availability and allowing recruitment of new individuals. Fire, a common disturbance, has been shown to influence seed germination in many ecosystems worldwide. The goal of this study was to determine the effects of fire, in the form of heat and smoke, on seed germination of six Florida scrub species (Chrysopsis highlandsensis, Eryngium cuneifolium, Hypericum cumulicola, Lechea cernua, Liatris tenuifolia, and Polygonella polygama). We applied dry heat, wet heat, and aqueous smoke treatments to the target species with control, low, and high levels for each treatment, using a novel approach with individual seeds closely monitored for germination time in microplate wells. Smoke treatments resulted in significantly higher germination percentages for three Florida scrub species, C. highlandsensis, E. cuneifolium, and L. cernua, as well as decreased time to germination for C. highlandsensis, but had no effect on the other three species. Dry heat treatments either had no effect or reduced percent germination in all species, while wet heat treatments resulted in virtually no germination. These results show fire effects in Florida scrub do include smoke-stimulated germination in some species, and most of our study species would not have reduced germination due to heat, especially if located within the insulating sands. Determining how fire influences seed germination will allow for more effective management techniques and higher success in propagating native plants. © 2017 South African Association of Botanists.

Weekley C.W.,Plant Ecology Program | Menges E.S.,Plant Ecology Program | Berry-Greenlee D.,U.S. Fish and Wildlife Service | Rickey M.A.,EMPSi Environmental Management and Planning Solutions Inc | And 2 more authors.
Ecological Restoration | Year: 2011

Exclusion of fire from pyrogenic ecosystems often results in changes in vegetation structure and the loss of biodiversity. Where landscape context constrains the application of fire, managers are applying mechanical treatments in conjunction with or as a surrogate for fire. We compared the effects of prescribed fire, mowing, mowing followed by fire, and a control at 2 fire-suppressed Florida scrub sites. Goals included increasing bare sand gaps, increasing endemic Florida scrub herbs, and reducing woody vegetation cover and height. We evaluated treatment effects on woody vegetation cover and height, ground cover (litter, lichens and bare ground), litter depth, and changes in the frequency and abundance of rare herbs prior to treatment and 1, 2 and 5 yr post-treatment. All treatments reduced woody vegetation cover and woody vegetation height relative to controls, and these effects often persisted for 5 yr post-treatment. In contrast, only treatments including fire resulted in consistent beneficial and long-lasting effects of increased bare sand cover, reduced litter and lichen cover, and reduced litter depth. Although the treatments had little effect on species composition and high variation made few comparisons statistically significant, burning (especially burning alone) increased occupancies and abundances of 2 rare species in some sites and in some years. In general, burning (with or without prior mowing) was more effective than mowing-alone or the control in restoring ground cover components and rare species populations. Fire provides unique benefits in the management of Florida scrub, and mechanical treatments are best used only when necessary to prepare sites for prescribed burning. ©2011 by the Board of Regents of the University of Wisconsin System.

Lovell J.T.,Colorado State University | Menges E.,Plant Ecology Program
Journal of the Torrey Botanical Society | Year: 2013

Seasonally flooded wetlands are periodically drained due to dry-season precipitation patterns. In the dry season, soil moisture can decrease to a level where wetland vegetation communities are subjected to drought stress. To understand the effects of drought conditions on the structure of seasonal wetland communities, we conducted a post-flooding reciprocal transplant experiment among three grass species across a soil moisture availability gradient at Archbold Biological Station, Florida, USA. We also manipulated the intensity of competition. We found that Cutthroat, the most upland species, responded physiologically to low soil moisture via root growth and leaf tissue moisture content, while the two flood-adapted species (Maidencane, Blue Maidencane), modulated growth and exhibited a dieback-resprout "drought deciduous" mechanism. These differential phenotypic responses, and not competition, were responsible for growth patterns in Florida seasonal wetlands in drought conditions. © Torrey Botanical Club.

Swift J.F.,Missouri Botanical Garden | Smith S.A.,Plant Ecology Program | Menges E.S.,Plant Ecology Program | Bassuner B.,Missouri Botanical Garden | Edwards C.E.,Missouri Botanical Garden
Conservation Genetics | Year: 2016

Polygala lewtonii is a federally endangered, amphicarpic plant with a mixed mating system and three types of flowers: (1) aboveground, chasmogamous flowers (i.e., open-pollinated; CH), (2) aboveground, cleistogamous flowers (i.e., closed, selfing; CL) and (3) CL flowers on belowground stems (amphicarpy). Aboveground seeds are ant-dispersed, whereas belowground seeds are spaced across the length of the rhizome. Here, we collected individuals of P. lewtonii at both range-wide and fine geographic scales and genotyped them at 11 microsatellite loci. We analyzed patterns of genetic diversity and structure to understand: (1) the predominant mating system (selfing or outcrossing), (2) the movement of pollen and seeds across the landscape, and (3) the optimal strategy to conserve the full range of genetic variation. P. lewtonii reproduces predominantly by selfing or bi-parental inbreeding, but reproduction occurred through each of the three flower types. Some individuals produced by selfing/inbreeding were tightly clustered spatially, and were likely produced either by belowground flowers or by aboveground flowers with limited seed dispersal. Other selfed/inbred individuals were spatially separated (maximum of 15 m), and were likely produced by aboveground flowers followed by seed dispersal by ants. Fine-scale patterns of genetic structure indicate that some gene flow is occurring among aboveground CH flowers but both pollen and outcrossed seeds are moving limited distances (maximum of 0.5 km). Because genetic variation is structured at a fine spatial scale, protecting many populations is necessary to fully conserve the genetic variation in P. lewtonii. Conservation seed banking, if accompanied by research on seed germination requirements, may also contribute to the effective protection of genetic variation in P. lewtonii. © 2016 Springer Science+Business Media Dordrecht

Menges E.S.,Plant Ecology Program | Pace-Aldana B.,Nature Conservancy | Haller S.J.,Plant Ecology Program | Smith S.A.,Plant Ecology Program
Southeastern Naturalist | Year: 2016

We collected data from 1998 to 2014 to describe the ecology of the highly endangered Florida scrub plant Crotalaria avonensis (Avon Park Harebells), and herein address several hypotheses based on what was known of its biology and the biology of co-occurring species. This perennial herbaceous legume occurs at 3 sites and prefers microsites with more cover by bare sand than vegetation. The population at an unprotected site has declined in size, but dynamics have been more stable at the 2 protected sites. Marked plants have shown high survival, slow and inconsistent growth, and occasional plant dormancy (usually 1-2 years). Avon Park Harebells is reproductively challenged, with very low rates of fruit set and infrequent visitation by required pollinators. The hardseeded fruits germinated at a rate of 13-56%; the germination speed seemed to increase after scarification, though the overall rate was less than for unscarified seeds. Unscarified seeds remained viable in the seed bank for at least 3 years. Seedlings recruited rarely, had moderate survival, began flowering at 4 years of age or later, and reached the size of median adult plants in 6-8 years. Herbivores affected 7-53% of plants in a given year, but plants showed rapid compensatory resprouting. Caging plants reduced herbivory and increased survival, growth, and flowering. Plants resprouted after fire and mechanical disturbance and exhibited high survival and growth, but repeated disturbances by vehicles caused increased mortality. Avon Park Harebells remains extremely endangered due to its limited range, small population sizes, and poor seedling recruitment. To help this species recover, we recommend fire management, protection from herbivory, introductions and augmentations, and further study of its pollination biology.

Schafer J.L.,Plant Ecology Program | Sullivan L.L.,Plant Ecology Program | Sullivan L.L.,Iowa State University | Weekley C.W.,Plant Ecology Program | Menges E.S.,Plant Ecology Program
Journal of the Torrey Botanical Society | Year: 2013

Conservation of a threatened species requires knowledge of the factors that affect its recruitment, survival, and reproduction. We conducted a long-term study on the demography of Paronychia chartacea ssp. chartacea, a short-lived, gynodioecious Florida rosemary scrub endemic. Specifically, we assessed the effects of habitat (rosemary scrub vs. roadsides), time-since-fire, microhabitat, and rainfall on recruitment, survival, flowering, and seed production. In addition, in a shorter-term study, we assessed the effects of habitat, time-since-fire, and gender on flower and seed production. Overall, approximately one-third of individuals survived more than one year and individuals most often flowered twice indicating that P. chartacea ssp. chartacea is an iteroparous, short-lived perennial, which is in contrast to its disjunct conspecific, the annual P. chartacea ssp. minima. Recruitment was higher in roadsides, but seed production was higher in rosemary scrub. Within rosemary scrub, recruitment was highest at intermediate times-since-fire and in the center of large gaps, the microhabitat with the greatest amount of bare sand. Median lifespan was longest in long unburned sites, suggesting that P. chartacea ssp. chartacea is able to persist despite litter accumulation and competition from shrubs. Rainfall had a positive effect on annual survival, but did not affect seedling recruitment. Females produced more seeds than hermaphrodites, indicating that females contribute more to population persistence. Our study suggests P. chartacea ssp. chartacea populations will persist under the 15-40 year fire return interval characteristic of regularly burned Florida rosemary scrub, but may not persist in roadsides if greater recruitment does not balance shorter lifespans. © Torrey Botanical Club.

Bertz C.A.,University of Mississippi | Menges E.S.,Plant Ecology Program
Castanea | Year: 2016

Roads have the potential to serve as dispersal corridors for invasion into pristine habitats for invasive exotic species. However, undisturbed habitats may also resist such invasion. Torpedograss (Panicum repens L.) is an aggressive invasive grass in many parts of the world and, although most problematic in lakes and ponds, frequently occurs in roadsides and in other disturbed habitats. We studied torpedograss dynamics along roadsides adjacent to upland habitats in south-central Florida to determine whether observed tiller population growth rates differed among roadside populations adjacent to different habitats. We also examined seasonal growth and persistence patterns of this invasive species in sand roads, quantifying torpedograss density, growth, and panicle production at 10 roadside sites every other month for 14 mo. Four populations were adjacent to disturbed habitats (pastures or disturbed Florida scrub) containing established populations of torpedograss, while six populations were adjacent to undisturbed Florida scrub lacking torpedograss. Population growth rates were negative in most roadsides neighboring undisturbed scrub, and positive when neighboring disturbed habitats. Tiller density, tiller height, and panicle production were all greatest in late summer, and tiller density increased with temperature and relative humidity. We observed no evidence of recruitment from seed. We never found any invasion of undisturbed Florida scrub, consistent with the hypothesis that undisturbed Florida scrub resists invasion. Results suggest that, in xeric habitats, land managers should give higher priority to restoring disturbed habitats or controlling expansion from disturbed habitat edges rather than to eradicating roadside populations of torpedograss. © 2016 Southern Appalachian Botanical Society.

Smith S.A.,Plant Ecology Program | Menges E.S.,Plant Ecology Program
PLoS ONE | Year: 2016

Euphorbia rosescens is a recently described plant that is narrowly endemic to the Lake Wales Ridge. Little is known of the ecology or life history of this diminutive, deeply rooted polygamodioecious perennial. We studied 13 subpopulations of this species from 2004-2012 from five habitats, sampling monthly during its growing season. Subpopulations were stable year-to-year with annual survivals > 90%, but with considerable within-year dynamics, peaking in density in April and dying back in the fall and winter. Stem densities did not vary among subpopulations, habitats, or by subpopulation gender. Annual plant dormancy was common and decreased subsequent survival. Belowground biomass averaged almost50 times higher than aboveground biomass. Subpopulations either consisted of entirely female individuals or a mixture of male and functionally andromonoecious individuals and these subpopulation genders remained stable across years. Overall, flowering has been dominated by female plants. Plants produced modest numbers of inflorescences (cyathia), and fruit production was very low. Although most plants survived fire by resprouting, fire decreased survival and had a short-term positive effect on floral production. Lack of fecundity and recruitment are concerns for this state-endangered species, but more information is needed on its breeding system and clonality to make specific management recommendations. © 2016 Smith, Menges. This is an open access article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited.

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