See discussions, stats, and author profiles for this publication at: https://www.researchgate.net/publication/318318929 Evaluating Removal of Competition on Morphology of Endangered Slender Rush-Pea ( Hoffmannseggia tenella... Article in Natural Areas Journal · July 2017 DOI: 10.3375/043.037.0311 CITATIONS READS 0 10 4 authors, including: Sandra Rideout-Hanzak David B Wester Texas A&M University - Kingsville Texas A&M University - Kingsville 20 PUBLICATIONS 91 CITATIONS 143 PUBLICATIONS 1,752 CITATIONS SEE PROFILE SEE PROFILE Weimin Xi Texas A&M University - Kingsville 62 PUBLICATIONS 423 CITATIONS SEE PROFILE Some of the authors of this publication are also working on these related projects: Restoration Planning and Evaluation Following Damage by the Southern Pine Beetle in a Sustainable Forest Management Context View project Comanche - Faith Ranches Research Project View project All content following this page was uploaded by Sandra Rideout-Hanzak on 13 November 2017. The user has requested enhancement of the downloaded file. Evaluating Removal of Competition on Morphology of Endangered Slender Rush- Pea (Hoffmannseggia tenella) Endemic to Southern Texas, USA Author(s): Ashley C. McCloughan, Sandra Rideout-Hanzak, David B. Wester and Weimin Xi Source: Natural Areas Journal, 37(3):382-393. Published By: Natural Areas Association https://doi.org/10.3375/043.037.0311 URL: http://www.bioone.org/doi/full/10.3375/043.037.0311 BioOne (www.bioone.org) is a nonprofit, online aggregation of core research in the biological, ecological, and environmental sciences. BioOne provides a sustainable online platform for over 170 journals and books published by nonprofit societies, associations, museums, institutions, and presses. Your use of this PDF, the BioOne Web site, and all posted and associated content indicates your acceptance of BioOne’s Terms of Use, available at www.bioone.org/page/terms_of_use. Usage of BioOne content is strictly limited to personal, educational, and non-commercial use. Commercial inquiries or rights and permissions requests should be directed to the individual publisher as copyright holder. BioOne sees sustainable scholarly publishing as an inherently collaborative enterprise connecting authors, nonprofit publishers, academic institutions, research libraries, and research funders in the common goal of maximizing access to critical research. R E S E A R C H A R T I C L E ABSTRACT: Slender rush-pea (Hoffmannseggia tenella) is an endangered herbaceous legume endemic to southern Texas. Agricultural expansion and invasive nonnative grasses have caused reductions in its • range, threatening existing populations. We compared three management techniques that control com- petition to no management (control) to determine effects on slender rush-pea survival and morphology. We treated some slender rush-pea plants with summer prescribed burning. In the mechanical treatment Evaluating Removal we controlled above-ground competition surrounding target slender rush-pea plants with a string trimmer and we removed both above- and below-ground competition with herbicide in the chemical treatment. of Competition No slender rush-pea plants died during our two-year study. Plants in each competition removal treatment produced more main stems than control plants at various times throughout the study. Summer prescribed on Morphology burning produced longer stems, while both summer burning and chemical treatment resulted in more leaves on the longest stem and more flowers than control plants at various times throughout the study. of Endangered Slender rush-pea individuals with more main stems, longer stems, and more leaves may be more robust and resilient to environmental stress. We speculate increased flower production may indicate enhanced Slender Rush-Pea reproduction. At the pasture scale herbicide treatment is not practical as it may eradicate remaining native plants. Summer prescribed burning may be the most effective method for increasing short-term robustness of slender rush-pea; mowing could be a temporary substitute when fire is impractical. Results (Hoffmannseggia indicate that slender rush-pea benefits from active management and control of competition from nonnative tenella) Endemic to grasses, and if managed properly slender rush-pea could persist in their presence. Index terms: endangered, herbaceous legume, Hoffmannseggia tenella, prescribed burning, removal of Southern Texas, USA competition Ashley C. McCloughan1 INTRODUCTION must quickly adapt—on the population and potentially the individual level. Among the 1Actagro Soil and Plant Health Presently, grasslands are some of the most problematic species in southern Texas is Technology Solutions threatened or endangered ecosystems Kleberg bluestem (Dichanthium annulatum 2282 Sugar Grove Rd. worldwide because of habitat loss and [Forssk.] Stapf), a C4 perennial bunchgrass Bowling Green, KY 42101 destruction through agriculture, urbaniza- native to India, China, and Northern Africa tion, and introduction of nonnative species, (Ortega et al. 2007; Ruffner and Barnes 2,4 Sandra Rideout-Hanzak which sometimes become invasive in nature 2012). It is a prolific seeder and displays David B. Wester2 (Sampson and Knopf 1994; Ruffner and a high tolerance for drought and cold, as Weimin Xi3 Barnes 2012). Recent unprecedented rates well as some salinity tolerance (Ortega et of spread of nonnative species into new al. 2007; TIPPC 2011). First introduced to habitats and ecosystems have forced native the central and southern Great Plains in the 2Caesar Kleberg Wildlife Research flora and fauna into direct competition with early 1900s for the purpose of improving Institute and Department of Animal, these new, and sometimes competitively pasture and rangeland forage, it is actually Rangeland and Wildlife Sciences superior, species—often to the detriment of lower forage quality than previously Texas A&M University-Kingsville of native communities (D’Antonio and thought, especially in southern Texas MSC 218 Vitousek 1992; Rice et al. 1997). Perennial (Ortega et al. 2007; Ruffner and Barnes Kingsville, TX 78363 grasses in particular are often introduced 2012). Not only has it degraded habitat and to new areas for either livestock forage lowered forage quality, its abilities to with- 3Department of Biological and Health (i.e., because of their tolerance for ex- stand grazing pressure, high temperatures, Sciences treme conditions) or to stabilize soils and and drought have allowed this nonnative Texas A&M University-Kingsville MSC 158, TAMUK prevent erosion (D’Antonio and Vitousek grass to spread unchecked across Texas Kingsville, TX 78363 1992; Ruffner and Barnes 2012). These and northern Mexico landscapes (Ortega introduced grasses present native plants et al. 2007). with novel competition for resources (e.g., • light, water, and nutrients) and may even- This invasion is of particular concern for tually eliminate native species, lowering a federally endangered species endemic overall biotic diversity of the community to southern Texas—slender rush-pea 4 Corresponding author: [email protected]; (D’Antonio and Vitousek 1992; McDonald (Hoffmannseggia tenella Tharp & L.O. 361-593-4546 and McPherson 2011). Williams). In the Fabaceae family, the flowering plant genus Hoffmannseggia Southern Texas hosts several highly in- currently consists of 21 identified species Natural Areas Journal 37:382–393 vasive nonnative grasses that present a and exhibits an amphitropical distribution challenge for native flora and fauna, which in dry subtropical and warm temperate 382 Natural Areas Journal Volume 37 (3), 2017 regions of North and South America (Simp- An ability to compete at the individual level most recent quantitative estimate was in son et al. 2004, 2005). Slender rush-pea may be expressed through morphological the “thousands” (USFWS 2008). It exists grows in former native short-grass prairie plasticity, which is a mechanism employed within remnant Western Gulf Coastal Plain communities found in clayey soils of by an individual to adjust to changes in its region of southern Texas in a semi-arid cli- blackland prairies and creek banks in the natural environment, allowing it to more mate. The location receives approximately Gulf Coastal Plain of southern Texas—par- successfully compete for niche space 83.6 cm (32.9 in) of annual mean rainfall ticularly in Nueces and Kleberg Counties, (Aarssen 1983; Crick and Grime 1987; with an average temperature fluctuation Texas (USFWS 1988). Craine and Dybzinski 2013). Some plants between 16.1 and 27.7 °C (61 and 82 °F) display this through alteration of pheno- (NOAA 2014). Study plants were located Slender rush-pea is an herbaceous perennial typic traits to suit variable environmental in Victoria clay soil, 1%–3% slope, fine, legume, 8–15 cm tall, with a woody taproot conditions. smectitic, hyperthermic Sodic Haplusterts and reddish color on older stems. Leaves (VcB) (NRCS 2014) just west of Carreta are alternate and bipinnately compound We know of only two studies on slender Creek. The sampling area—roughly 0.8 with 11–13 oblong leaflets, which are rush-pea. One study focused on population ha (2 ac)—is free of gravesites and has slightly hairy on the undersurface (USFWS vigor as determined by population size and been subjected to uniform management of 1985). Flowers are typically salmon color, density (Poole and Janssen 1996). Pressly periodic mowing for several decades. Al- and are produced between early March (unpubl. data) studied survival, number