HR: 09:30h
AN: H51M-07    [Abstracts]
TI: Resource homogenization in degraded arid landscapes induced by fire – erosion interactions
AU: * Ravi, S
EM: sujith@virginia.edu
AF: University of Virginia, Department of Environmental Sciences, 291 McCormick Rd, Charlottesville, VA 22903, United States
AU: D'Odorico, P
EM: paolo@virginia.edu
AF: University of Virginia, Department of Environmental Sciences, 291 McCormick Rd, Charlottesville, VA 22903, United States
AU: Wang, L
EM: lixin@virginia.edu
AF: University of Virginia, Department of Environmental Sciences, 291 McCormick Rd, Charlottesville, VA 22903, United States
AU: Collins, S L
EM: scollins@sevilleta.unm.edu
AF: University of New Mexico, Department of Biology, Albuquerque, NM 87131, United States
AU: White, C S
EM: cswhite@sevilleta.unm.edu
AF: University of New Mexico, Department of Biology, Albuquerque, NM 87131, United States
AU: Okin, G S
EM: okin@ucla.edu
AF: University of California, Department of Geography, 1255 Bunche Hall, Los Angeles, CA 90095, United States
AB: Hydrological and aeolian processes are major drivers in the dynamics of arid landscapes in that they redistribute soil resources with important implications on the composition and spatial patterns of dryland vegetation. These processes are thought to play a major role in the conversion of disturbed desert grasslands into shrublands, with possible impacts on regional climate and desertification. At its early stages the grassland-to-shrubland transition can be still reversible and fires have been shown to contribute to the reversibility of the system. Even though fires are know to interact both with wind and water erosion, an understanding of these interactions and of their effect on aridland degradation is still missing. Here we use field manipulation experiments in a grass-shrub transition zone in the Chihuahuan desert to show how the interaction of fires with erosion processes may affect the distribution of soil resources with consequent effects on the pace of land degradation processes. Using microtopography measurements and isotopic analyses, we provide experimental evidence for the occurrence of post-fire enhancement of soil erosion, and relate this effect to the weakening of interparticle bonding forces associated with the emergence of fire-induced soil hydrophobicity. We also show how this effect favors the reversibility of the early stages of shrub-to-grass transition through the redistribution of soil resources from the fertile shrub-dominated areas (or "fertility islands") to the bare soil interspaces.
DE: 1809 Desertification
DE: 1813 Eco-hydrology
DE: 1815 Erosion
DE: 1838 Infiltration
SC: Hydrology [H]
MN: 2007 Fall Meeting