Soil seed bank dynamics in rangelands with increasing invastion of heteropogon contortus or eragrostis lehmann

Authors: GRACE, JOSHUA - Texas A&M University; RIDEOUT-HANZAK, SANDRA - Texas A&M University; STANKO, RANDY - Texas A&M University; Acosta-Martinez, Veronica; ORTEGA-SANTOS, ALFONSO - Texas A&M University; WESTER, DAVID - Texas A&M University

Submitted to: Journal of Arid Environments
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 7/14/2019
Publication Date: 8/15/2019
Citation: Grace, J., Rideout-Hanzak, S., Stanko, R., Acosta Martinez, V., Ortega-Santos, A., Wester, D. 2019. Soil seed bank dynamics in rangelands with increasing invastion of heteropogon contortus or eragrostis lehmann. Journal of Arid Environments. online.

Interpretive Summary: Invasive grasses threaten rangelands through their negative effects on plant community composition and diversity. Identifying impacts of invasive grasses on soil seed banks is critical in developing restoration strategies for these rangelands. Tanglehead and lovegrass have increased in abundance and distribution throughout the Texas Coastal Sand Plain. Scientists from Texas A&M University and ARS in Lubbock, Texas examined effects of these invasive grasses on seed banks for three years in sites under the following degrees of invasion: (1) native plant-dominated communities (none), (2) native/invasive mixtures, and (3) invasive-dominated communities The study demonstrated that emerged seed banks of native sites generally were equally diverse and rich compared to communities dominated by either tanglehead or lovegrass, suggesting that restoration of these sites may be feasible without seed input.

Technical Abstract: Invasive grasses threaten rangelands through their negative effects on plant community composition and diversity. Identifying impacts of invasive grasses on soil seed banks is critical in developing restoration strategies for these rangelands. Tanglehead (Heteropogon contortus [L.] P. Beauv. ex Roem. and Schult.) and Lehmann lovegrass (Eragrostis Lehmanniana Nees) have increased in abundance and distribution throughout the Texas Coastal Sand Plain. We examined effects of tanglehead and Lehmann lovegrass on seed banks in sites that were characterized by (1) native plant-dominated communities, (2) invasive-dominated communities, and (3) native/invasive mixtures in 3 consecutive years. The seedling emergence method was used to determine seed bank size (number of emerged seedlings), species composition, richness and diversity. More tanglehead seedlings emerged in tanglehead-dominated sites than native sites in 2013 and 2014. Seed bank sizes of native grasses and forbs were unaffected tanglehead in 2013 and 2014; there were fewer native grasses but more forbs in tanglehead-dominated communities in 2015. More Lehmann lovegrass seedlings emerged in Lehmann lovegrass-affected sites; effects of Lehmann lovegrass on forb seed banks were not consistent among years. Tanglehead did not affect seed bank species richness or diversity; Lehmann lovegrass reduced richness and diversity in 1 of 3 years. Tanglehead and Lehmann lovegrass affected mean species composition in 1 of 3 years and 2 of 3 years, respectively. The emerged seed banks of native sites generally were equally diverse and rich compared to communities dominated by tanglehead or Lehmann lovegrass, suggesting that restoration of these sites may be feasible without seed input.