Using Ecological Niche Modeling to Predict Distributions and Effects of Climate Change on Two Endangered Plant Species, Leavenworthia texana and Physaria pallida

dc.contributor.advisorMartina, Jason P.
dc.contributor.authorFogel, Brianna
dc.contributor.committeeMemberWilliamson, Paula S.
dc.contributor.committeeMemberCastellanos, Adrian A.
dc.description.abstractLeavenworthia texana (Texas golden gladecress) and Physaria pallida (White bladderpod) are endangered wetland plant species found exclusively on the Weches glade geologic formation in East Texas. These plants are under threat from invasive species, habitat loss and fragmentation, and climate change, with population numbers dwindling in recent decades. This research used a combination of simple mapping techniques and ecological niche modeling to predict species distributions and locate additional plant populations. For the simple mapping, Texas Parks and Wildlife Department’s (TPWD) Texas Natural Diversity Database (TXNDD) population data, critical habitat layers from US Fish and Wildlife Service (USFWS) Threatened & Endangered Species Active Critical Habitat Report, and potential Weches glade formation outcrops from TPWD were overlapped to highlight areas of potential plant occurrence. For the ecological niche model (ENM), I used a combination of environmental variables pertinent to the species (such as soil characteristics, land cover data, and temperature and precipitation records) and known species occurrence records from TXNDD to determine locations that are mathematically predicted to be habitat areas of high suitability. This ENM was created using the R program MAXENT. A climate change ENM was also created using five Global Climate Models (GCMs) for the years 2011-2040 and 2041-2070 using Shared Socioeconomic Pathways (SSPs) 3-7.0 and 5-8.5. The total land area of intersecting layers produced by the L. texana simple mapping results displayed 0.719 km2 of potential important habitat, and the total land area of intersecting layers produced by the P. pallida simple mapping results displayed 0.193 km2 of potential important habitat. Surveys conducting using these results in Spring 2022 yielded five populations of Physaria pallida and one location of Leavenworthia texana. Two ENMs were created, one for L. texana and one for P. pallida. The training AUC values were 0.918 for P. pallida’s ENM and 0.934 for L. texana’s ENM. In total, the L. texana ENM highlighted 664.827 km2 worth of land across Nacogdoches, San Augustine, and Sabine counties that averaged above a 0.7 suitability. The P. pallida ENM produced 3.180 km2 worth of land averaging above a 0.7 suitability. Survey efforts using the L. texana ENM in Spring 2023 yielded four populations of L. texana, all of which have already been documented by TPWD. Predictions from the climate change ENM shows a drastic decrease in the future amount of potentially suitable habitat for L. texana. Twenty climate change ENMs for L. texana were created and averaged to understand the general trend across all five selected GCMs. By 2070, the ENMs highlight only 5.182 km2 of potential suitable land, a 99.2205% reduction from the originally constructed present day L. texana ENM. The results from this climate change ENM hold implications for future conservation and management strategies for this species. Conservation efforts should be intensified in areas where L. texana will still have suitable niches in the next 50 years. These results also suggest locations for potential reintroductions and refuge sites. Successfully keeping these endangered species from extinction relies on identifying areas that may warrant monitoring and protection. The ecological niche models developed in this project can be used by government conservation agencies to inform real decision-making processes that will benefit both Leavenworthia texana and Physaria pallida and aid in their future recovery.
dc.format.extent103 pages
dc.format.medium1 file (.pdf)
dc.identifier.citationFogel, B. (2023). Using ecological niche modeling to predict distributions and effects of climate change on two endangered plant species, Leavenworthia texana and Physaria pallida (Unpublished thesis). Texas State University, San Marcos, Texas.
dc.titleUsing Ecological Niche Modeling to Predict Distributions and Effects of Climate Change on Two Endangered Plant Species, Leavenworthia texana and Physaria pallida
dc.typeThesis and Conservation Biology State University of Science


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