Effects of a Windstorm and Forest Fire on Chemical Losses from Forested Watersheds and on the Quality of Receiving Streams

Abstract

A severe natural windstorm followed by a high intensity forest fire caused significant increases in runoff and in losses of N, P and K from 2 small Precambrian watersheds. Both the windstorm and the fire had significant effects on water and chemical yields. Water yields in the 2 basins were 1.6 and 1.8 times the pre-impact means, respectively, in the year after the burn. Maximum chemical losses were observed for nitrate, with values of 3.4 and 9 times the pre-impact means for the 2 basins in the year after the burn. Increases in annual yields of most chemical parameters were 1.1-2.9 times the background. Increased concentrations and increased flow volumes may be responsible for the increased nutrient losses.