Characteristics of Hydrological Runoff in an Artificial Coniferous Forest with Delayed Thinning and Its Long-term Changes

Abstract

Characteristics of hydrological runoff in an artificial coniferous forest with delayed thinning were evaluated by comparing with hydrological data collected simultaneously in a reference watershed. In addition, the effect of thinning on the runoff was evaluated. An obvious increase in base flow was observed after thinning, and the main reason for this increase was thought to be the decrease in evapotranspiration by thinning. The increased base flow was observed for at least three years in the watershed with delayed thinning and for one year in the reference watershed. The runoffs on rainy days in the watershed with delayed thinning tend to be larger than those in the reference watershed in the cases of small or moderate runoffs. On the other hand for the drought-period runoffs, obvious difference is not found in the two watersheds with the effect of thinning being excluded.