Arbuscular mycorrhiza: A linkage of plant, soil and surface hydrologic processes in a southwest grassland

Abstract

A three-year randomized field study was undertaken to evaluate the effects of prescribed burning and the intense rainfall events associated with the summer monsoon of southern Arizona, specifically examining the interchange between the plant, soil and surface hydrologic processes within a savanna. The effects of fire and rainfall treatments were evaluated by examining their specific effects on vegetation, arbuscular mycorrhizal fungi (AMF), soil structure, soil nutrient capital, surface runoff and sediment. In addition to the field study, two factorial greenhouse studies were completed in conjunction with the field study. The objectives of the greenhouse studies were: (1) to test the effects of prescribed fire and high intensity rainfall on AMF infectivity potential, and (2) to examine the effect of mycotrophy on the biomass production of native and introduced grasses grown in pasteurized and native soils. A third study examined the development of an empirical model to estimate sediment production from the field study's plots. The objectives of this third study were: (1) to develop the empirical model using two years of collected sediment, and (2) to compare model estimates with the commonly used Revised Universal Soil Loss Equation (RUSLE) model. The results of these studies indicate that a integrated mechanism exists between the plant community and biotic and physical soil processes, which when disturbed affect the hydrology of the watershed.