Lehmann lovegrass and black grama drought response in the Jornada Desert 2021

Percent cover for Bouteloua eriopoda and Eragrostis
lehmanniana was collected over four years at Mt.
Summerford (latitude 32.516, longitude -106.802), New
Mexico State University's Chihuahuan Desert Rangeland Research Center
(CDRRC), Doña Ana County, New Mexico. In June 2016, permanent 2m × 2m
plots were installed to evaluate change in percent cover of B. eriopoda
and E. lehmanniana in response to precipitation manipulation treatments of
+80% (irrigated), -80% (drought), and ambient (control) precipitation. We
used a randomized complete block design with six replicates per
treatment, with blocks perpendicular to the slope, for a total of 18
plots. Plot locations were adjusted to exclude ant nests, and plant
species other than annuals. Cover of other plant species was <1% at
the beginning of the study. This cover included Aristida turnipes (0.13%),
Panicum hallii (0.20%), and Sporobolus spp. (0.15%). At the upslope border
of each plot, we installed galvanized flashing to a depth of approximately
11.4 cm to block surface flow of water onto plots. Metal rebar stakes were
driven into the ground at each corner of each plot as permanent markers. A
large nail embedded in the center of each plot was used to standardize
placement of data collection frames. Rainout shelters,
constructed according to the design by Yahdjian and Sala (2002), extended
0.5 m beyond the boundaries of the plots. Rainout shelters manipulated
precipitation received, so 151 that irrigated plots received 180% ambient
precipitation, drought plots received 20% of ambient precipitation, and
control plots received 100% ambient precipitation. Due to repeated
malfunctions including pipe leaks and electronic component failures, the
maintenance of the irrigation systems became untenable after 2017.
Therefore, irrigation plots were excluded and only control and drought
data were included in 2018 and 2019 analyses.