Small mammal herbivory and grassland recovery potential in the Chihuahuan Desert

Authors: SVEJCAR, LAUREN - New Mexico State University; Bestelmeyer, Brandon; James, Darren; Peters, Debra

Submitted to: Journal of Arid Environments
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 4/1/2019
Publication Date: 7/1/2019
Citation: Svejcar, L., Bestelmeyer, B.T., James, D.K., Peters, D.C. 2019. Small mammal herbivory and grassland recovery potential in the Chihuahuan Desert. Journal of Arid Environments. 166:11-16. https://doi.org/10.1016/j.jaridenv.2019.04.00.
DOI: https://doi.org/10.1016/j.jaridenv.2019.04.001

Interpretive Summary: In many arid ecosystems, shrub encroachment is associated with the loss of valuable perennial grasses. Increased native rodent and lagomorph abundance associated with shrub encroachment can have negative effects on grass persistence and restoration. In the Chihuahuan Desert, herbivore abundance can be up to two times greater in degraded Prosopis glandulosa (honey mesquite) shrublands than in intact Bouteloua eriopoda (black grama) grasslands. We tested the recovery potential of B. eriopoda patches in shrub-dominated, grass-dominated and ecotone (grass and shrub co-dominated) states that were exposed to or protected from native rodent and lagomorph herbivores. Although herbivore abundance was greater in shrub-dominated states than the other states for the given time periods, there was little difference in recruitment and re-establishment of B. eriopoda among states and in response to rodent exclusion. Because increased herbivore abundance in shrub-dominated states did not constrain grass recovery potential, other factors are likely to be more important constraints on perennial grasses recovery in the Chihuahuan Desert.

Technical Abstract: In many arid ecosystems, shrub encroachment is associated with the loss of valuable perennial grasses. Increased native rodent and lagomorph abundance associated with shrub encroachment can have negative effects on grass persistence and restoration. In the Chihuahuan Desert, herbivore abundance can be up to two times greater in degraded Prosopis glandulosa (honey mesquite) shrublands than in intact Bouteloua eriopoda (black grama) grasslands. We tested the recovery potential of B. eriopoda patches in shrub-dominated, grass-dominated and ecotone (grass and shrub co-dominated) states that were exposed to or protected from native rodent and lagomorph herbivores. Herbivore exclosures and control quadrats were established in a replicated blocked design. A disturbance of 40cm x 40cm was created in the center of a B. eriopoda grass patch in each treatment quadrat in 2001, whereby all above ground biomass was removed in order to examine the ability of B. eriopoda to recolonize disturbed areas. The disturbed areas were measured for recruitment and re-establishment of B. eriopoda in 2002, 2005 and 2008. Although herbivore abundance was greater in shrub-dominated states than the other states for the given time periods, there was little difference in recruitment and re-establishment of B. eriopoda among states and in response to rodent exclusion. Because increased herbivore abundance in shrub-dominated states did not constrain grass recovery potential, other factors are likely to be more important constraints on perennial grasses recovery in the Chihuahuan Desert.