|Title||Patchiness in wind erosion-deposition patterns in response to a recent state change reversal in the Chihuahuan Desert|
|Publication Type||Conference Paper|
|Year of Publication||2011|
|Authors||Pillsbury FC, Peters DC, Yao J, Okin GS|
|Conference Name||US-International Association for Landscape Ecology|
|Conference Location||Portland, OR|
|ARIS Log Number||262578|
Shifts from shrub-dominated states to grasslands are believed to be irreversible as a result of positive feedbacks between woody plants and soil properties. In the Chihuahuan Desert, mesquite (Prosopis glandulosa) expansion into black grama (Bouteloua eriopoda) grasslands is maintained by wind redistribution of material from bare soil gaps to canopies beneath woody plants. However, a series of wet years starting in 2006 resulted in increased grass production, biomass, and lateral cover. We hypothesized that this increase in grasses modified the spatial distribution of gaps and therefore the patchiness of wind erosion-deposition dynamics. Further, we expected that positive feedbacks promoting grass recovery would act to interrupt long-term patterns of mesquite expansion. We tested this hypothesis by examining patterns of sand flux and changes in the spatial distribution of gaps through time in grasslands and shrublands at the Jornada Basin LTER from 1998 – 2010. Wind-driven sediment deposition decreased markedly at mesquite-dominated sites beginning in 2007. The spatial variability of sediment deposition also decreased, indicating that an increase in the amount and homogeneity in herbaceous vegetation in previously unvegetated gaps reduced saltation by sand particles and stabilized the soil surface. These results indicate that a reduction in the spatial variability of bare gaps and changes in the structure of vegetated patches reduce the patchiness of wind erosion and deposition. Successful remediation of arid grasslands depends on our ability to exploit the altered spatial dynamics that have accompanied recent state change reversals.