Long-term declining trends in Chihuahuan Desert forage production in relation to stocking rates and climate

TitleLong-term declining trends in Chihuahuan Desert forage production in relation to stocking rates and climate
Publication TypeConference Paper
Year of Publication2021
AuthorsMcIntosh M., Holechek J.L, Cibils A.F., Estell R.E., Spiegal S.A.
Conference NameSociety for Range Management Meeting Abstracts
Date Published02/15/2021
ARIS Log Number383764
Abstract

We analyzed a 25-yr time series (1995 – 2019) of stocking rate (SR), ambient temperature, precipitation, and perennial grass production (PGP) at a 4000-ha site in the Chihuahuan Desert. Using the Proc Glimmix procedure in SAS 9.4, we analyzed effects of two SRs (light: 25-30% vs conservative: 31-40% forage use rate), year, and SR × year to evaluate time trends. Stocking rates had no effect on PGP (P = 0.25), but year did (P < 0.01). Stocking rate × year did not affect PGP (P = 0.94). We found a 75% reduction in in kg * ha-1 PGP when the first (115.4 ± 18.7 kg DM perennial grass) vs last three (28.27 ± 18.67 kg DM perennial grass) study years periods were compared (P < 0.01). Annual average ambient temperature during the 25-y study increased by more than 1°C (beginning: 15.22 ± 0.2 vs end: 16.7 ± 0.2°C). Mean maximum June temperature (P < 0.01; r = - 0.39) was negatively associated with PGP. Conversely, PGP was positively associated with total annual precipitation (P < 0.01; r = 0.28). The interaction of June mean maximum temperature and annual precipitation negatively affected PGP (P < 0.01). These preliminary results suggest that climate may have an overriding effect on Chihuahuan Desert forage production even when appropriate stocking rates are applied. Sustainability of beef production systems on southwest rangeland will increasingly be hampered by forage yields less than 100 lb*ac-1; the point at which point livestock grazing becomes financially unsound.