杉木林取代阔叶林后土壤生物学活性变化的研究

通过对福建省南平市溪后安曹下取代阔叶林的70a生杉木车产林（山坡）、32a生杉木“青年林”（山坡）及前茬阔叶林（山脊）土壤生物学活性连续2a的比较研究结果表明，与山脊上前茬的阔叶林相比，70a生杉木丰产林土壤微生物总数、生理类群的数量减少、活性下降；土壤酶活性减弱；呼吸作用强度（内源）及添加基质的外源呼吸作用强度降低，土壤中有机质分解和腐殖质再合成程度降低．32a生杉木“青年林”土壤生物学活性下降则更为明显，说明从杉木取代阔叶林（头耕土）起，土壤生化活性及土壤肥力就存在明显下降现象，轮伐期缩短或林地连栽杉木代数增加，而不采取恢复地力措施，杉木林地地力衰退将更为明显．

CHANGES OF SOIL BIOLOGICAL ACTIVITIES AFTER THE REPLACEMENT OF BROADLEAVED FOREST BY CHINESE FIR FOREST

A comparative study was conducted for 2 a on soil biological activities of a 70-year-old fact-growingand high-yield Chinese fir forest (hillside), and a 32-year-old"young forest" of Chinese fir (hillside), whichwere originally occupied by broadleaved forests in Ancaoxia, Xihou, Nanping. The results showed that thetotal number and groups of microbes in soil of the 70-year-old Chinese fir forest were decreased; soilenzyme activities abated; soil endogenous and accidental respiration intensity reduced; the degree of organicmaterial decomposition and humus recomposition were dropped, and the soil biological activities of 32yearold"young forest" of Chinese fir reduced more obviously, in comparison with the original broadleaved forests(ridge). This shows that the soil biochemical activities and fertility have ben reduce evidently since thereplacement of broadleaved forests by Chinese fir. If the rotation was shortened or the repeated plantationincreased, soil degradation of Chinese fir forest would become more evident.