杉林连栽对土壤养分的影响及其反馈

EFFECT OF CONTINUOUS CROPPING WITH CHINESE FIR UPON SOIL NUTRIENTS AND ITS FEEDBACK

在福建南平溪后村的暗红壤上,选择土壤形态性质相同、而杉木连栽次数不同的林地组成生态系列,进行横向比较。调查分析表明,杉林连栽过程中,由于生物学特征或林业措施的影响,导致土壤磷酸铝、铁、钙盐,交换性钾、钙,以及一定程度上全氮含量的下降;并且因为皆伐和造林过程中的土壤侵蚀,使表土层变薄,从而导致土壤中各种养分贮量(包括有机质、氮和各种灰分元素)的大幅度降低,结果是杉木生长量也逐届递降。相关分析表明,在土壤的上述两种变化中,后者对减产的作用远大于前者。

On the dark red soils in Nanping County of Fujian Province, plots being similar in the shape and properties of soil but different in the frequency of continous cropping with Chinese fir were selected to from a ecological sequence for transverse comparison. From the results of survey and analyses it turned out that in the continuous cropping process Al-P,Fe-P, and Ca-P, Ex-K, Ex-Ca, and to a certain extent the total N content decreased, owing to the influence of. the biological nature of Chinese fir or the cutting and silvicultural measures on it; and the storages of various nutrients in soil also decreased to a large extent due to the reason that the thickness of surface soil was thinned by soil erosion as the result of clear cutting and silvicultural measures. It followed from this that the growth of Chinese fir also decreased from a cropping term to another. Results of correlation demonstrated that between the aboved-mentioned nutrient decreasing tendencies the effect of the latter was far greater.