Forests and Streamflow A Discussion of the Hoyt-Troxell Report

The Hoyt-Troxell report is an attack upon the widely accepted belief that watershed vegetation must be kept intact for the most favorable influence upon stream flow and erosion and flood control, and, that the negative values of the vegetation, because of transpiration losses, are far outweighed by the beneficial effects. The Hoyt-Troxell report has had wide circulation; from several parts of the World we learn that it has mislead engineers as to the value of watershed cover for the region in which the study was conducted. The conflicting evidence of various recent contributions emphasizes the importance of correctly evaluating the factors involved and that a complete algebraic summation must be made of all plus and minus factors to furnish the correct basis for watershed protection measures. Dr. Lowdermilk's careful analysis of the authors' data and conclusions provokes and calls for further discussion of this report and of investigation of the subject in general by foresters and engineers.