Viewpoint: The Role of Drought in Range Management

Abstract

Drought is an ambiguous term, subject to expectation and the weight of emphasis on meteorological, agricultural, hydrological and socioeconomic dimensions. Uncertainty associated with the identification of drought often results in a lagged response in reducing stocking rates. This delay reduces vegetation cover, increasing the potential for accelerated erosion following the drought. The long-term consequences of accelerated erosion are a reduction of soil depth, a decline in soil structure and a decrease in infiltration rate and water storage capacity. Less water stored on a site hastens the onset of plant stress, effectively increasing the perceived frequency and consequences of drought. Management and policy tools must improve the integration of economic and ecological aspects of drought-induced de-stocking decisions, especially by incorporating the long-term irreversible costs of erosion.

Increasing flexibility in rangeland management during drought

“…In August 2012, severe or greater drought affected 67% of livestock value in the US (USDA ERS 2012), and cattle and calf numbers were at their lowest level in 60 years as of February 2013(USDA NASS 2013. Failure to graze rangelands properly during drought can cause ecological degradation, including loss of plant cover and accelerated soil erosion (Thurow and Taylor 1999). Markets are a second, interrelated source of risk to agricultural operations during drought.…”

“…We draw on the experiences of Wyoming ranchers, who encounter drought more often than most of the US (Soule 1992), to understand drought management and suggest components of a proactive drought policy for US rangelands. Drought management involves increasing resilience of the ranching operation to the risks posed by a variable climate (Thurow and Taylor 1999, McKeon et al 2009). Livestock ranching operations are vulnerable to production risk because forage production in rangeland ecosystems is linked to growing season precipitation which is highly variable within and between years (Knapp and Smith 2001).…”

Summary of science, activities, programs, and policies that influence the rangewide conservation of Greater Sage-Grouse (Centrocercus urophasianus)

“…Conclusions from a review of the effects of herbivory on bluebunch wheatgrass (Pseudoroegneria spicata), an important sagebrush associate, indicated (1) utilization levels of 30 to 40 percent under deferred grazing systems is a recommended maximum use-level if maintaining the community is desirable; (2) onetime growing season utilization levels of more than 50 percent have long-term (up to a decade) impacts on plant vigor and productivity (even if followed by complete protection); and (3) grazing following the growing season has little effect, although yield reductions the following year may occur if grazed to 2-inch stubble height (Anderson, 1991). Annual and seasonal monitoring of production and standing crop, with subsequent removal of livestock as range utilization reaches capacity (Holechek and others, 1989;Thurow and Taylor, 1999) is important for providing for habitat quality rangewide and would be facilitated by development within local monitoring, planning, and adaptive management cycles.…”

A viability model to assess the sustainability of mixed herds under climatic uncertainty

“…Pastoralism often takes place in variable environments such as drylands and breeders adopt strategies to anticipate the impact of droughts [33]. Herd diversification is one such strategy that allows coping with uncertainty.…”