Long-term Trends in Perennial Grass Production, Precipitation and Temperature in the Chihuahuan Desert

TitleLong-term Trends in Perennial Grass Production, Precipitation and Temperature in the Chihuahuan Desert
Publication TypeConference Paper
Year of Publication2019
AuthorsMcIntosh M.M, Holechek J.L, Cibils A, Estell RE
Conference Name72nd Society for Range Management International Meeting
Date Published02/2019
PublisherSociety for Range Management Meeting Abstracts
Conference LocationMinneapolis, Minnesota
ARIS Log Number358982
Abstract

Rising temperatures and more frequent droughts are posing new challenges to livestock producers in the Southwest. Our objective was to evaluate long-term perennial grass production (PGP) in the Chihuahuan Desert in relation to ambient temperature and precipitation. PGP was correlated with precipitation (mm) and ambient temperature (oC) over a 49-year period (1969 – 2017). Increasing precipitation in December through September was associated with higher PGP (r = 0.74, n = 49) whereas rising maximum average temperatures in March through September were associated with a reduction in PGP (r = -0.54, n = 49). Two-sample t-tests comparing averages of each variable for the first and last 25 years of the study period (1969-1993 vs. 1994-2017) revealed that mean PGP decreased by 35% (220.7 ± 12.5 vs. 143.92 ± 15.89 kg DM*ha-1; P < 0.01), precipitation was more variable and decreased by 21% (264.88 ± 1.30 vs. 211.13 ± 16.67 mm; P = 0.01), whereas mean maximum temperature (24.48 ± 0.14 vs. 25.22 ± 0.13°C; P < 0.01) and mean temperature (14.45 ± 0.13 vs. 15.04 ± 0.13°C; P < 0.01) increased by  0.7oC and 0.6o C, respectively. Over this 49-year period, Chihuahuan Desert rangelands at our research site lost 35% of grazing capacity (approximately 84 AUMs/1000 ha [7 AUYs/1000 ha]). Our research shows that increased temperatures and more frequent droughts are severely impacting forage and range livestock production in the southwest.