Impact of forest harvesting on river runoff in the Xiaoxing’an Mountains of China

Abstract

Using the runoff experiment method in a large basin combined with the contrast experiment in a small watershed, and based on the runoff and forest resources data for the past 35 years, this paper studied the serial changes of river runoff in the Xiaoxing an Mountains after forest harvesting. The results showed that the river flow increased in the initial ten years after forest harvesting, but decreased gradually with the growth and crown closure of the Larix gmelini plantations. The river flow tended to be the same or even lower than the level before harvesting. The river runoff had a close correlation with annual rainfall, the size of forest harvesting and regeneration. A significant positive correlation was observed between the annual flow and the size of forest harvesting, which resulted in the increase of river runoff after forest harvesting. Forest harvesting could also significantly increase the peak flood and snowmelt runoff. There was a negative correlation between the regenerated forest area and annual flow, and thus, forest regeneration would decrease annual flow.