Desertification of Rangelands

Authors: Peters, Debra; ARCHER, STEVE - University Of Arizona; Bestelmeyer, Brandon; BROOKS, MATTHEW - Us Geological Survey (USGS); BROWN, JOEL - Natural Resources Conservation Service (NRCS, USDA); COMRIE, ANDREW - University Of Arizona; GIMBLETT, H. RANDY - University Of Arizona; GOLDSTEIN, JOSHUA - Colorado State University; Havstad, Kris; LOPEZ-HOFFMAN, LAURA - University Of Arizona; MONGER, H. CURTIS - New Mexico State University; OKIN, GREG - University Of California; Rango, Albert; SALA, OSVALDO - Arizona State University; TWEEDIE, CRAIG - University Of Texas - El Paso; VIVONI, ENRIQUE - Arizona State University

Submitted to: Book Chapter
Publication Type: Book / Chapter
Publication Acceptance Date: 2/1/2013
Publication Date: 4/1/2013
Citation: Peters, D.C., Archer, S.R., Bestelmeyer, B.T., Brooks, M.L., Brown, J., Comrie, A., Gimblett, H., Goldstein, J.H., Havstad, K.M., Lopez-Hoffman, L., Monger, H., Okin, G.S., Rango, A., Sala, O.E., Tweedie, C., Vivoni, E. 2013. Desertification of Rangelands. In: Pielke Sr., R.A., editor. Climate Vulnerabiliy: Understanding and Addressing Threats to Essential Resources. Academic Press. p. 239-258.

Interpretive Summary: Desertification, the broad-scale conversion of perennial grasslands to dominance by xerophytic shrubs, has affected drylands globally over the past several centuries. Desertification is a cumulative threat that includes both climatic (e.g., drought) and land-use drivers (e.g., livestock overgrazing, fire). In this chapter, we determine the vulnerability of different ecosystem services to changes in drivers and ecosystem states, with a focus on the American Southwest. We: (1) describe key services in drylands, (2) identify consequences of desertification to each service, and (3) explore the vulnerability of each service to future state-changes if existing threats intensify and new threats emerge. We then: determine threats expected to have the greatest future impact, provide potential actions for mitigation, and conclude with recommendations.

Technical Abstract: Desertification, the broad-scale conversion of perennial grasslands to dominance by xerophytic shrubs, and the attendant consequences to ecosystem services has affected arid and semiarid regions globally over the past several centuries. This state change is expected to continue in the future as environmental drivers continue to change. It is generally well-recognized that desertification is a cumulative threat that explicitly includes both climatic (e.g., drought) and land-use drivers (e.g., livestock overgrazing and inappropriate conversions of rangeland to cropland). However, a basis for ranking the relative importance of these drivers is lacking for many locations. In addition, the emergence of additional drivers (e.g., non-native forbs and grasses modifying historic fire regimes), will result in even more complex dynamics in the future. Clearly, directional changes in climate can have unanticipated effects, in particular for dryland regions with low and variable precipitation and high temperatures in the growing season. However, any change in climate will be operating across diverse landscapes that include a mosaic of human-dominated and natural states, each governed by different drivers and susceptible to different threats. Accounting for the separate and interactive effects of these threats on grassland-shrubland transitions will be necessary as we move forward into a difficult to predict, if not unknown, environmental world.