三峡库区小集水区复合生态系统的水分及养分动态

WATER AND NUTRIENT CIRCULATIONS IN COMPLEX ECOSYSTEM OF SMALL CATCHMENT IN THE THREE-GORGE REGION

以三峡库区小集水区复合生态系统为对象 ,定量研究了其中不同子系统的水分和养分动态过程。结果表明 :(1)平均径流系数是裸地 >草地 >菜地 >柏木林 >桔园 ;(2 )年养分流失量是裸地>桔园 >菜地 >草地 >柏木林 ,桔园和菜地的径流系数较小 ,但其径流中养分含量较高 ,导致其输出养分总量较大 ;(3)菜地和桔园由于输出果菜 ,导致系统N、P循环效率的降低 ;(4)各子系统中P的流失较厉害 。

Taking complex ecosystem of small catchment in the Three Gorge Region as a research object, water and nutrient circulations in different sub systems were studied quantitatively. The relationship of average coefficients of the surface run off in different sub systems was in following order: the coefficient in bared land > in grassland > in vegetable plot > in \%Cupressus\% forest > in orchard. The relationship of annual nutrient loss was: in bared land > in orchard > in vegetable plot > in grassland > in \%Cupressus\% forest. Although the coefficients of the surface run off were low in orchard and vegetable plot, the run off in the two sub systems contained more nutrients, resulting in a more serious nutrient loss. The output of nutrient in bare land was higher than those in other subsystems because of its high coefficients of the surface run off and nutrient contents in the run off.The cycling rates of N and P in orchard and vegetable plot decreased as a result of output. The loss of P in each sub systems was higher than that of N, and the loss of P in \%Cupressus\% forest was lower than that in the grassland.Soil erosion was serious in bare land,orchard,and vegetable plot,so it was an important problem to prevent soil erosion from artificial agriculture vegatation in this kind of catchment.