In order to determine the reduction of nitrogen and phosphorus losses among different stand improvement patterns

Taxus mairei

Torreya grandis

Illicium henryi

Ardisia crenata were chosen as four different stand improvement tree species to improve Phyllostachy edulis forest structure

and the volumes of runoff and concentrations of nitrogen and phosphorous were measured from January 2013 to October 2014. Results showed that the total runoff of five forest stands were 3.06～9.22 m3 in 15 runoff events. The losses of total nitrogen were 7.6 times of the losses of total phosphorus

and the losses of ammonium nitrogen were 2.5 times of the losses of nitrate nitrogen. Stand improvement could reduce the ratio of ammonium nitrogen to nitrate nitrogen. The runoff was reduced by 40.0%～66.8% in these four stand improvement patterns in two years compared with Phyllostachy edulis pure forest. The accumulative losses of total phosphorus were reduced by 64.0%～83.8% in four stand improvement patterns compared with Phyllostachy edulis pure forest

and the corresponding values were 49.1%～78.8% for total nitrogen

37.4%～76.2% for nitrate nitrogen

and 42.8%～80.4% for ammonium nitrogen. The Taxus mairei + Phyllostachy edulis forest had greatest reduction effect on runoff and nitrogen and phosphorus losses among four forest stand improvement patterns.