Time filter

Source Type

Venus, FL, United States

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

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.

Discover hidden collaborations