PARENT SESSION
Symposium #12: Natural Recovery and Restoration of Disturbed Desert Environments in the Mojave Desert .
Organized by: RH Webb and KH Berry
Tuesday, August 6. 8:00 AM to 11:30 AM. Maricopa Meeting Room, TCC.
Resistance and resilience of biological soil crusts to soil surface disturbance in the Mojave Desert.
Phillips, Susan*,1, Belnap, Jayne1, 1 US Geological Survey, Moab, UT
ABSTRACT- Biological soil crusts (BSC), a community of lichens, mosses, and cyanobacteria found on soil surfaces, are an essential component of arid and semi-arid ecosystems. They are important for soil stability, decreasing sediment yield from both wind and water erosion, they provide fixed nitrogen, and decrease surface albedo. In the Mojave Desert, BSCs have their highest cover on silty soils and/or those with significant gypsum, limestone, or grussy granite content. Crusts generally do not co-occur with desert pavement or when sand content is >85%. BSCs are easily disturbed and/or destroyed by soil surface disturbances such as livestock grazing, off-road recreational vehicles, and military training exercises. Land managers need the ability to distinguish surfaces on the basis of resistance to disturbance, as well as expected recovery times after disturbance. Within a given climate regime, we show that resistance to disturbance is best predicted by soil texture, using soil stability, nitrogen-fixation, and chlorophyll levels as measures. Recovery rates are most dependent on climatic history, in particular precipitation levels. Within a given climate regime, severity of disturbance and soil texture best determine recovery rates, using species composition, species cover, nitrogen-fixation and chlorophyll as measures. Initial studies in the Mojave Desert indicate that crusts require more than a century for recovery if significant shearing occurs. We present a generalized model for predicting resistance and resilience for biological soil crusts throughout the western US.
KEY WORDS: Biological soil crusts, arid lands, Mojave desert, recovery