杉木多世代连栽的土壤水分和养分变化

通过在南平溪后安曹下的杂木林、１代、２代及３代杉木人工林中设立标准地，对杉木林取代杂木林后及随杉林多代连栽土壤水分和养分的变化进行研究，结果表明：随着杉木林取代杂木林及连续栽植代数的增加，土壤保水和供水能力下降，土壤大部分全量部分全量养分含量减少，土壤供肥和保肥能力下降，导致杉木林分生产力下降，这是杉木连栽后衰退的重要特征之一。

Variation in Soil Water and Nutrients between Different Rotation Stands of Chinese Fir

A research was performed on a series of plots with similar conditions in broad leaved forest and in the first ,the second ,the third generations of Chinese fir to examine the effects of substituting Chinese fir for broad leaved forest and continuous monoculture with Chinese fir at the same site on soil water,soil nutrient.The results indicated that,with the substitution of Chinese fir plantation for broad leaved forest and the increasing of continuous plantations of Chinese fir,the ability of soil water keeping and supply descended,most of the soil total nutrient contents decreased,the ability of soil fertility supplying and keeping declined,which affected the Chinese fir growth directly,It is one of the main reasons for soil degradation at the sites with continuous Chinese fir planting.