Title | Vulnerability and triggers in threshold development: models from the Chihuahuan Desert |
Publication Type | Conference Paper |
Year of Publication | 2008 |
Authors | Bestelmeyer BT, Herrick JE, Steele C |
Conference Name | Society for Range Management |
Date Published | January 26-31, 2 |
Conference Location | Louisville, KY |
ARIS Log Number | 223384 |
Keywords | threshold development |
Abstract | We review models developed for the Draw and Loamy ecological sites in Major Land Resource Area 42.2 in southwestern New Mexico and review empirical support obtained for parts of the model. We describe evidence for 1) vulnerability to transitions and associated triggers and 2) the characteristics of alternative states. Remote-sensing based evidence supports the notion that fragmentation of grass cover creates vulnerability to transition, and anecdotal evidence supports the notion that high intensity storms serve as triggers that initiate erosion and gully formation. Field measurements indicate that degradation of soil structure, increased run-off, and reduced water infiltration are important feedbacks components driving the transition and reinforcing state changes. These relationships are strongly mediated by soil horizon development differences within the ecological site. The state-and-transition model thus links these scientific studies and provides indicators that can be used by managers to gauge the likelihood of threshold development. |