Desertification, land use, and the transformation of global drylands

Abstract

Desertification is an escalating concern in global drylands, yet assessments to guide management and policy responses are limited by ambiguity concerning the definition of “desertification” and what processes are involved. To improve clarity, we propose that assessments of desertification and land transformation be placed within a state change–land‐use change (SC–LUC) framework. This framework considers desertification as state changes occurring within the context of particular land uses (eg rangeland, cropland) that interact with land‐use change. State changes that can be readily reversed are distinguished from regime shifts, which are state changes involving persistent alterations to vegetation or soil properties. Pressures driving the transformation of rangelands to other types of land uses may be low, fluctuating, or high, and may influence and be influenced by state change. We discuss how the SC–LUC perspective can guide more effective assessment of desertification and management of drylands.

Land degradation trend assessment over Iberia during 1982-2012

“…Despite the short percentage of degraded pixels that experienced land cover changes, which seems to indicate that those changes do not represent also the main reason for land degradation in the considered period, the analysis of the affected land cover reveals to be important. This feature suggests that land degradation occurs within the lifetime of some land cover types and consequently supports the new conceptual approach proposed by Bestelmeyer et al (2015) wherein desertification consists of land states shifting within concrete land uses (e.g. rangeland, cropland).…”

“…Consequently it also labels desertification for the cases where land degradation occurs in arid and semi-arid environments. The monitoring and early detection of desertification land degradation processes are vital to avoid the irreversible decline of land conditions and the setup of desertification that can lead to ecosystems regime shifts (Bestelmeyer et al, 2015). However, the assessment of land degradation and desertification is a very complex process, starting with the definition of both concepts (Higginbottom and Symeonakis, 2014).…”

Climate change and physical disturbance cause similar community shifts in biological soil crusts

“…Although physical disturbances can be mitigated (41) and future precipitation patterns are uncertain (28,42), increasing temperatures (meeting or exceeding those imposed by warming treatments) are considered a near certainty across many dryland ecosystems (29). Thus, our results suggest that climate change will affect biocrusts to an extent similar to changes observed with physical disturbance, leading to a landscape-level shift to early successional states with seemingly limited potential for a return to late successional states.…”

“…threats from physical disturbances due to development, agriculture, and other human activities (32,40,41). Understanding the magnitude of threats to biocrusts from both climate change scenarios and novel disturbance regimes is thus a necessary step for predicting future ecological states and developing comprehensive management plans in drylands.…”

A Spanner in the Works: Human–Elephant Conflict Complicates the Food–Water–Energy Nexus in Drylands of Africa

“…Still, almost all of the tropical dry forests today are exposed to a variety of threats including habitat loss and climate change (Miles et al, 2006;Bestelmeyer et al, 2015). Habitat loss and degradation is driven by a combination of factors, all relevant in the food-energy-water nexus.…”