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Summary: Testing a non-equilibrium model of rangeland vegetation
dynamics in Mongolia
MARIA E. FERNANDEZ-GIMENEZ* and BARBARA ALLEN-DIAZ{
*School of Renewable Natural Resources, 325 Biological Sciences East, University of Arizona, Tuscon, AZ
85721, USA; and {Department of Environmental Science, Policy and Management, Ecosystem Sciences
Division, 151 Hilgard Hall #3110, University of California, Berkeley, CA 94720±3110, USA
Summary
1. Few studies have tested the applicability of current non-equilibrium models of
rangeland vegetation dynamics to a particular ecosystem, or across a range of sys-
tems that might be expected to respond dierently to grazing. This study assessed
the extent to which the non-equilibrium persistent (NEP) model of rangeland vege-
tation dynamics applies to three distinct Mongolian rangeland ecosystems, the
desert-steppe, steppe and mountain-steppe.
2. Standing biomass, vegetation cover and composition, and species richness and
diversity were examined along grazing pressure gradients in ecological zones of dif-
fering productivity and interannual variability in precipitation.
3. In the desert-steppe, biomass, functional group cover, richness and diversity did
not vary along grazing pressure gradients, but all vegetation variables except the
cover of weedy annuals and unpalatable forbs varied signi®cantly between years.
Vegetation dynamics in this zone largely conformed to the NEP model of range-
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