Thesis (Ph. D.)--University of Florida, 2007. / Includes bibliographical references (p. 200-225). Also available via the World Wide Web: http://etd.fcla.edu/UF/UFE0021367/stewart_s.pdf

Thesis (M. Phil.)--University of Hong Kong, 1998. / Includes bibliographical references (leaves 110-119).

Thesis (M.S.)--Montana State University--Bozeman, 2005. / Typescript. Chairperson, Graduate Committee: Jian-Yi liu. Includes bibliographical references (leaves 92-94).

Spiranthes Parksii Correll is an endangered orchid of Texas. Populations of S. parksii are threatened by habitat loss and degradation resulting from human population growth and attendant development and resource extraction. Conservation easements have been established for the protection of the species, but little is known about the population dynamics of S. parksii and the biotic and abiotic factors which drive them. A baseline of ecological information is necessary to the creation of effective management plans for the conservation of this species. The work presented here is an experimental investigation of the affects of large herbivores on S. parksii population dynamics. We explored direct impacts of herbivore browsing as well as indirect impacts resulting from removal of neighboring vegetation on S. parksii population fluctuations and the demographic parameters underlying them. To determine direct herbivore affects on demographic characteristics and their implications for S. parksii population dynamics, we established 32, 1.5mx1.5m plots in areas of high S. parksii abundance. Each of the plots was randomly assigned one of two treatments: herbivore exclusion and control. Demographic parameters were recorded for each individual located within the plots. The data suggest that large and small herbivore browsing affects different lifecycle transitions through removal of photosynthetic and reproductive tissue. These transition alterations have the potential to affect S. parksii population growth. To investigate the indirect impacts of herbivory on S. parksii population dynamics, we established 32 5mx5m plots. Each plot was randomly assigned one of four fertilizer treatments: control, nitrogen addition, phosphorus addition, and nitrogen and phosphorus additions. One half of each plot was randomly assigned one of two biomass removal treatments: unaltered control and biomass removal during orchid dormancy. Demographic data was collected for individuals within the plots. Plots with phosphorus and nitrogen phosphorus additions generally differed regarding orchid demographic variables from nitrogen addition plots and unfertilized controls. Also, available light tended to be greater during orchid flowering in plots with biomass removed than in unclipped controls. A complete understanding of both direct and indirect herbivore impacts on S. parksii population dynamics is necessary for effective conservation of this endangered orchid.

published_or_final_version / Zoology / Master / Master of Philosophy

Using four AFLP markers and seven polymorphic microsatellite loci, we examined the genetic structure of the rare and endangered Spiranthes parksii Correll (Orchidaceae). Spiranthes parksii is not distinguishable from sympatric S. cernua (L.) Rich based on these data, though low levels of polymorphisms exist within both. These low levels of genetic diversity are likely a result of high levels of agamospermic reproduction through adventitious embryony. These results suggest that both S. parksii, as well as the sympatric, open flower form of S. cernua, are products of the more widely distributed S. cernua complex. Further, another local form of S. cernua, distinguished by its tendency to produce closed flowers is genetically distinct from both S. parksii, as well as the openflower form of S. cernua, as shown by AFLPs and microsatellite loci. This is the first known set of microsatellite primers developed specifically for use in Spiranthes. The application of these markers may be used to address other unresolved relationships among species of Spiranthes, many of which are also endangered or have populations in decline.

Wireless sensor networks (WSNs) represent a class of miniaturized information systems designed to monitor physical environments. These smart monitoring systems form collaborative networks utilizing autonomous sensing, data-collection, and processing to provide real-time analytics of observed environments. As a fundamental research area in pervasive computing and envisioned as large-scale autonomous networks of communicating nodes capable of monitoring conditional metrics over vast geographic areas, WSNs have the potential to provide researchers and conservationists with increased knowledge of the intricacies and interrelationships of disparate environments. The author addressed the problem of developing a methodology for the design and deployment of WSNs in uncontrolled and harsh outdoor environments. Within the context of a research and conservation field study of flora, the author developed a model for deployment of WSNs within the domain of microclimate habitat monitoring. The goal of this study was to contribute to the body of knowledge in WSN research by developing a model for deployment that was scientifically sound and replicable. To accomplish this goal, the author conducted an investigation of current technologies associated with WSNs, their capabilities, and their applications specific to the stated domain. To validate this model, the author deployed a WSN for monitoring the microclimate habitats of a population of Spiranthes lacera var. gracilis, common name, slender ladies' tresses. During this field study, the WSN performed according to design and produced sufficient data to provide an accurate representation of the microclimate habitats of the objects of study. As a contribution to the WSN research body of knowledge, the author used an SDLC methodology to provide a pragmatic approach to deployment focused on the elements of nuance specific to WSNs for microclimate habitat monitoring.

Spiranthes parksii Correll is an endemic terrestrial orchid to the Post Oak Savannah of East Texas and is currently listed as federally endangered. The construction of Twin Oaks landfill, approximately 20 km east of College Station, TX, will destroy an estimated 379 S. parksii individuals and 44.7 ha of its habitat. Research has been funded to mitigate for this loss and includes documenting demographics, life cycle, local and landscape habitat, and on-site transplantation of S. parksii. Results found that S. parksii was highly variable between years at Twin Oaks and might be due to seasonal rainfall in rosette and early flowering growth. It was also found variable in its production of a rosette and influorescence from year to year. Individual plants were found to occur farther from drainages in higher count years, probably due to soil moisture, although further research should be conducted to confirm this hypothesis. A significant difference (p = 0.026) was found for percent canopy cover > 2 m above 1 m x 1 m quadrats with and without S. parksii, with a mean of 55 percent with S. parksii and 97 percent without S. parksii. A Non-Metric Multidimensional Scaling ordination revealed three different combinations of herbaceous species that occur with S. parksii, which were driven by the presence of three dominant bunch grasses of the Post Oak Savannah: Schizachyrium scoparium, Chasmanthium laxum var. sessiliflorum, and Andropogon ternarius. A close to significant difference (p = 0.07) was found for the leaf litter depth between quadrats with and without S. parksii, with a fewer number of stacked leaves with S. parksii. Analysis of aerial images indicated woody encroachment on Twin Oaks from 1958 to 2004 in areas that have not been mechanically cleared. Additionally, S. parksii was found to persist in an open savannah landscape and likely occurred in the same locations and more widespread in 1958 than are currently found. Transplantation of S. parksii was documented to be successful by a soil-intact method. While a bare-root method showed success with S. cernua, no conclusions can be made of its success for S. parksii due to a low sample size (n = 10).

A population of a critically endangered species Spiranthes spiralis was discovered in 1980 in the National Natural Monument Pastviště u Fínů near village Albrechtice, close to Sušice city. Since 1985 the number of flowering individuals in this population has been annually monitored. Since autumn 1998 all the specimen found there have been marked and biometrically measured. During these periods (12 or 26 years, respectively), large year-on-year fluctuations in the number of flowering plants and in the survival of the individual rosettes have been recorded. The main aim of my work was to assess the effect of weather conditions (temperature, precipitation, the number of days of snow) on the population dynamics and on the fitness of plants (leaf area, probability of flowering and probability of death). The year-round lower temperature and the wet end of autumn during the previous year (t-1) together with the wet spring of the following year (t) had a positive effect on the leaf area during the period of maximal rosette growth (end May in the year t). The probability of flowering was positively affected by the lower temperatures in May and June in the previous year (t-1) and in August just before flowering (year t). The probability of death (in the year t) was increased when the March precipitation (in t) and October temperatures (in t-1) were low. The average number of seeds in the capsule was 1528 ? 885 (s.d.). The number of flowers was positively correlated with the number of mature capsules. However, it did not affect the ratio of mature capsules. Capsules developed on average from 44% ? 24.6 % (s.d.) of the flowers. The average life time of individual plant cohorts was 4.7 years. The number of rosettes per each position was variable from 1 to 7 rosettes (73.2% positions had only 1 rosette). The annual life cycle of the underground organs is described at the end of the thesis.