PARENT SESSION
Oral Session #73: Applied Ecology and Ecological Economics. Presiding: J. Hof.
Friday, August 10, 2001. 8:00 AM to 12:00 PM. Hall of Ideas P&Q.
Prescribed fire, monsoon rainfall and arbuscular mycorrhizal influences on erosion processes in semi-arid grasslands.
O'Dea, Mary1, 1
ABSTRACT- In Southwest grasslands, arbuscular mycorrhizae (AM) have an important role in plant community dynamics and in the susceptibility of surface soil layers to erosion. In this study, changes in mycorrhizal variables and associated erosion parameters were measured following the summer monsoon in two burned grassland types. The interaction of prescribed fire and the monsoon rainfall significantly (p ≤ 0.05) decreased levels of stable aggregates, perennial grass and fungal variables, but increased hillslope sediment yield. Strong positive and significant (p≤ 0.05) correlations between aggregate stability and AM parameters resulted in the development of an empirical erosion model for semi-arid grassland types (r2 = 0.58, p=0.02). When compared with RUSLE estimates, estimates from the AM model were better estimators of actual erosion losses, with estimates not significantly different from plot sediment samples. Results from this study infer that soil fungal properties strongly influence the structural characteristics of the soil and upland erosion responses in semi-arid grasslands.
KEY WORDS: prescribed fire, arbuscular mycorrhizae, erosion, semi-arid grasslands