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  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
1

Effects of Prescribed Burns on Grassland Breeding Birds at Mississippi Sandhill Crane National Wildlife Refuge

Ruffman, Elizabeth A 20 December 2013 (has links)
There has been a critical decline in grassland bird populations due to habitat fragmentation and deterioration, and suppression of natural fires. Alteration of the disturbance cycle may lead to changes in vegetation structure and thus habitat suitability for breeding grassland birds. Management practices at the Mississippi Sandhill Crane National Wildlife Refuge, including the use of prescribed fire, are in need of evaluation. My study asked what frequency of prescribed burns is necessary to support breeding grassland birds and whether vegetation structure varies among burn units. In this study, bird abundance and species richness did not differ significantly among burn units and vegetation cover-type was not a strong predictor of these factors either. There was evidence of site utilization by breeding grassland birds immediately following a burn, which suggests that the bird community is able to recovery quickly post-fire and these units may serve as viable habitat for breeding grassland birds.
2

Arthropod Abundance and Diversity in Restored Longleaf Pine Savannas at Abita Creek Flatwoods Preserve

Nighohossian, Cara B 16 May 2014 (has links)
The objective of this study is to determine whether changes in arthropod community structure in restored longleaf pine savannas corresponds to differences in vegetation structure often associated with burn frequency. Longleaf pine savannas are fire-maintained ecosystems characteristic of the southeastern United States and have experienced severe declines (around 97%) since European settlement. Changes in fire regime have been instrumental in the declines. Restoration of these ecosystems has involved reinstitution of periodic burnings to promote and maintain vegetative characteristics of the savannas. This study investigates trends in arthropod communities from areas heavily invaded by hardwood shrubs against those dominated by longleaf pines and associated vegetation. These data suggest that herb-dominated sites have higher overall diversity. While overall abundance differences were not found, significant differences have been detected at the order and family level, indicating that vegetation structure and periodic burning are important factors in maintaining arthropod communities characteristic of these savannas.
3

Ecology of Yellow Rail (Coturnicops Noveboracensis) Overwintering in Coastal Pine Savannas of the Northern Gulf of Mexico

Morris, Kelly Marie 14 August 2015 (has links)
The Yellow Rail (Coturnicops noveboracensis) is a migratory nongame bird of high conservation priority throughout its entire range. The objectives of this study were: (1) assess Yellow Rail occupancy in the context of prescribed fire regime in pine savanna habitats of Mississippi and Alabama and (2) assess Yellow Rail habitat use in pine savanna habitats of coastal Mississippi. Yellow Rail occupancy decreased significantly with time since fire and increased with grassland patch size. Throughout the study area Yellow Rail maintained small (mean = 3.37 ha) home ranges aggregated within study areas, indicating suitable habitat may be limited. Yellow Rail used areas dominated by Aristida stricta and Carex spp. They used locations with lower woody percent cover, greater herbaceous height structure and lower frequency of trees than locations outside their home range. This research highlights the continued need to prioritize conservation and management of open grasslands and pine savanna habitats.
4

Determining the pollination mechanism of a problematic invasive species in the Gulf South: Triadica sebifera

Clark, Jennifer Wester 13 May 2016 (has links)
Understanding the ecology of invasive species is vital to curb the homogenizing of ecosystems, yet the pollination mechanisms of the Chinese tallow tree (Triadica sebifera) in its introduced habitat remain ambiguous. This study examines self-pollination, wind pollination, and flower-visiting insects of tallow in a bottomland hardwood forest and Longleaf pine savannah in the U.S. Gulf South. These data suggest that self-pollination and airborne pollination are possible, but likely rare occurrences, although the possibility of apoxisis was not investigated. Seed production in exclusion experiments was significantly less than in open-pollinated flowers, and wind dispersal of tallow pollen dropped to essentially zero 8 meters from the source. Results show that tallow is primarily bee pollinated, with external pollen loads of Apis, Melissodes, and halictids visiting at similar rates, and Xylocopa species visiting less frequently. The researchers believe that to date, this is the first study of the pollination mechanisms of T. sebifera in its introduced range and recommend further study to understand the ecology of this destructive invasive species.

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