ABSTRACT

Chicuahuan Desert landscapes exemplify the ecological conditions, vulnerability and management issues found in semi-arid regions around the globe. The goal of the Jornada Basin Long-Term Ecological Research program is to identify the key factors that control ecosystem dynamics in semi-arid landscapes, with the objective of understanding the causes and consequences of desertification. Pervious LTER work focused primarily at the scale of a single plant-interspace and on the redistribution of soil resources at that scale. However, the intrinsic nature of semi-arid regions, including the prevalence of high winds and short intense precipitation events in landscapes with substantial topographic variability, promotes the redistribution of materials at larger scales. The central hypothesis of the LTER phase is that landscape position and linkages among landscape units exert important influences on ecosystem dynamics and biotic patterns within sites. We propose to build on our understanding of resource redistribution at the plant-interspace scale in several ways. We will synthesize existing long-term data with new studies on linkages among landscape units, and we will conduct simulation modeling efforts to test the relative importance of within- versus between-unit processes. We will initiate or expand studies of landscape fluxes of water, nutrients, and organisms in order to evaluate key processes affecting ecosystem dynamics at this scale. We will also employ remote sensing to assess fluxes and processes at larger spatial scales. Cross-site studies will be used to test the generality of our hypotheses for application to management and redemption of semi-arid ecosystems and desertified landscapes.

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