Post fire induced soil water repellency-Modeling short and long-term processes

Soil water repellency has direct implications to hydrological as well as geomorphological processes, especially in fire-prone ecosystems. Five predominant mechanisms have been described as generating water repellency in soils: fungal and microbial activity, growth of particular vegetation species, organic matter, heating of the soils by wildfires and soil characteristics. Herein we synthesize among these mechanisms and propose a general model describing the long-term properties of water repellency in soils. Using non-linear regression analysis methods we compare among different variants of the model in order to assess the relative role of vegetation on water-repellency dynamics. We suggest that following a wildfire event hydrophobic peak soil properties are dictated by vegetation properties, but that the rapid decrease is not associated with the vegetation. Following wildfires, the recovery of the ecosystem commences and water-repellency is characterized by increased predominance of the biotic activity. Thus, the general pattern of a rapid decrease and a long-term increase in water repellency can be described by a mathematical model presented herein.