Stream Chemistry Responses to Disturbance

The vegetation on 12 watersheds at Coweeta has been altered by experimentation during the past 50 years. Disturbances include light selection cutting and logging, clearcutting without roads and no products removed, clearcutting with various methods of commercial logging, agricultural cropping, conversion of mixed hardwoods to white pine, and conversion of hardwoods to grass accompanied by applications of lime, fertilizer, and subsequent herbicide application. Also, hardwoods on two of the control watersheds have been partially defoliated by insects during the spring for varying periods of time. Two stream-gaging sites are on fourth-order streams and these larger drainages contain a combination of undisturbed and treated watersheds. A brief summary of each vegetation type represented during the period of stream chemistry record is given in Table 25.1. (see Chapter 1 for details of treatments).