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ARS Home » Plains Area » Fort Collins, Colorado » Center for Agricultural Resources Research » Rangeland Resources & Systems Research » Research » Publications at this Location » Publication #334913
Title: Tradeoffs between vegetation management goals and livestock production under Adapative Grazing Management

Author
item Augustine, David
item Derner, Justin
item FERNANDEZ-GIMINEZ, MARIA - Colorado State University
item BRISKE, DAVID - Texas A&M University
item Wilmer, Hailey
item Porensky, Lauren
item TATE, KEN - University Of California
item ROCHE, LESLIE - University Of California

Submitted to: Meeting Proceedings
Publication Type: Proceedings
Publication Acceptance Date: 3/30/2016
Publication Date: 8/22/2016
Citation: Augustine, D.J., Derner, J.D., Fernandez-Giminez, M., Briske, D., Wilmer, H.N., Porensky, L.M., Tate, K., Roche, L. 2016. Tradeoffs between vegetation management goals and livestock production under Adapative Grazing Management. Meeting Proceedings. 2015canada.rangelandcongress.org/pdf/paper/X_IRC.

Interpretive Summary:

Technical Abstract: Rangeland ecosystems are characterized by substantial temporal variability in weather overlaid on spatial variability associated with topography and soils (Fuhlendorf et al. 2012). Semiarid rangelands in particular are characterized by more extreme intra- and inter-annual variation in precipitation than mesic rangelands (Augustine 2010), and droughts continue to create major financial hardship for livestock producers around the world. Strategies for coping with drought include reducing livestock numbers, leasing forage, temporarily grazing rangeland beyond its capacity, and increasing supplemental feed, but these involve significant economic or ecological costs. Alternative approaches to increase enterprise flexibility in responding to drought are clearly needed (Kachergis et al. 2014). Managing the spatial distribution of livestock with the goal of resting some pastures and “grassbanking” this forage during periods of above-average precipitation could enhance ranch-scale carrying capacity during subsequent droughts, but has not been evaluated at scales relevant to livestock producers. In 2012, we initiated an adaptive grazing management experiment in the shortgrass steppe of Colorado, USA where 11 stakeholders representing ranchers, stand and federal land management agencies, and non-governmental conservation/environmental organizations were assembled to 1) choose and prioritize desired ecosystem services, 2) determine management objectives which include enhancing the abundance of palatable, perennial C3 grasses within this C4-dominated grassland, and enhancing enterprise resilience to drought through grassbanking, 3) determine criteria and/or triggers for movement of livestock among pastures in an adaptive manner to achieve desired services, and 4) select appropriate monitoring approaches to assess management success through attainment of objectives, and inform adaptive management strategies. Pastures managed by the stakeholder group (adaptive grazing management; AGM) are paired with pastures receiving traditional, season-long (mid-May through early October) continuous grazing management (TGM) at the same moderate stocking rate in a replicated experimental design (N = 10 pastures per treatment; 130 ha per pasture). Yearling cattle in the AGM treatment are managed as a single herd that is rotated among pastures during the growing season, with the objective of grazing 8 of 10 pastures (and resting the remaining 2 pastures) given average precipitation, and adjusting this grazing plan in response to intrannual precipitation variability. As a result, stocking density is 10-fold greater in the AGM compared to the TGM treatment (1.7 steers/ha vs. 0.17 steers/ha), and the length of time that high stock densities are maintained in a given AGM pasture depends on growing season conditions. In 2014, cattle were moved among pastures when one of three triggers – residual forage biomass, cattle behavior, or maximum number of grazing days - was achieved in the currently grazed pasture. In 2015, the maximum days threshold was removed such that moves among pastures were only based on forage biomass and cattle behavior. Due to 2 consecutive years of above-average spring precipitation and forage production rates, the AGM herd grazed 7 of 10 pastures in 2014 and 4 of 10 pastures in 2015. Thus, a substantial portion of the landscape under adaptive grazing management was rested in 2014 and/or 2015. Residual biomass at the end of the grazing season was 54% greater (difference of 149 + 56 kg/ha) in rested AGM pastures relative to TGM pastures in 2014. Furthermore, the rate of increase in density of western wheatgrass (Pascopyrum smithii) tillers during 2013 – 2015 was marginally greater in pastures rested in 2014 (' = 0.54 tillers/m2) compared to paired TGM pastures (' = 0.38; paired t = 0.53, P =0.098). Concurrent with these desired changes in veget