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Abstract
Soil water repellency is partularly common in unburned chaparral, and its degree and duration can be influenced by seasonal weather conditions. Water repellency tends to increase in dry soils, whil eit decreases or vanishes following precipitation or extended periods of soil moisture. The 15426 ha Williams Fire provided an opportunity to investigate post-fire fluctuations in water repellency over a 1-year period. Soil water repellency was measured at the surface, and at 2-cm and 4-cm depths along six east-west positioned transects located within the chaparral-dominated San Dimas Experimental Forest. During the winter and spring, seasonal variation in the degree of surface water repellency appeared to be inversely proportional to antecedent rainfall and soil moisture conditions. Precipitation through December reduced the proportion of surface 'moderate or higher repellency' from 49 to 4% as soil wetness increased to 12%. Throughout the summer, soil wetness remained below 2%; however, surface soils remained 'wettable', with the proportion of surface 'moderate or higher repellency' never returning to the early post-fire amounf of 47%. Interestingly, at the 4-cm depth, the proportion of 'moderate or higher repellency' remained at levels > 25% throughout the summer dry season.
Citation
Hubbert, K.R.; Oriol, V. 2005. Temporal fluctuations in soil water repellency following wildfire in chaparral steeplands, southern California. International J. Wildland Fire 14(4), 439-447. doi:10.1071/WF05036
