Data from: Native lagomorphs suppress grass establishment in a shrub‐encroached, semiarid grassland

Shrub encroachment into arid grasslands has been associated with reduced
grass abundance, increased soil erosion, and local declines in
biodiversity. Livestock overgrazing and the associated reduction of fine
fuels has been a primary driver of shrub encroachment in the southwestern
United States, but shrublands continue to persist despite livestock
removal and grassland restoration efforts. We hypothesized that herbivory
feedbacks from native mammals may contribute to continued suppression of
grasses after the removal of livestock. Our herbivore exclusion experiment
in southeastern Arizona included five treatment levels and allowed access
to native mammals based on their relative body size, separating the
effects of rodents, lagomorphs, and mule deer. We included two control
treatments and replicated each treatment 10 times (n = 50). We introduced
uniform divisions of lawn sod (Cynodon dactylon) into each exclosure for
24-hour periods prior to (n = 2) and following (n = 2) the monsoon rains
and used motion-activated cameras to document herbivore visitations. In
the pre-monsoon trials, treatments that allowed lagomorph access had less
sod biomass relative to other treatments (p < 0.001), averaging 44%
( 36%) and 29% ( 45%) remaining biomass after the 24-hour trial periods.
Following the onset of monsoons, differences in remaining biomass among
treatments disappeared. Desert cottontails (Sylvilagus audubonii) were
detected more frequently than any of the other 11 herbivore species
present at the site, accounting for 83% of detections during the
pre-monsoon trials. Significantly more (p < 0.001) desert
cottontails were detected during the pre-monsoon trials (2,077) compared
to the post-monsoon trials (174), which coincided with biomass removal
from lagomorph accessible treatments. We conclude that desert cottontails
are significant consumers of herbaceous vegetation in shrub-encroached
arid grasslands and they, along with other native herbivores, may act as a
biotic feedback contributing to the competitive advantage and persistence
of shrubs.