岷江上游不同树种林地客土混合对土壤生物化学性质和枯落叶分解的影响

Influences of soil mixing of different forests on the biochemical characteristics and litter decomposition on upper reach of Minjiang River

人工纯林的长期经营会引发连栽障碍，影响森林的可持续发展，解决途径是引进更新树种形成混交林。为了指导四川岷江上游人工纯林更新树种和混交比例的选择，尝试通过针阔叶树种林地腐殖质土壤及其枯落物的客置和混合原位培养试验，探讨不同树种种间关系的协调性。结果表明：（1）连香树、云南松和云杉林地经过各种客土混合后酶活性普遍都有所提高，而在糙皮桦林地，经云南松土壤客土混合后酶活性普遍有所下降，经云杉土壤客土混合后脲酶和过氧化氢酶活性有不同程度的提高，蔗糖酶活性却有所下降；（2）连香树和云南松林地经过各种客土混合后，加速了c和N由枯落物进入土壤，而在糙皮桦和云杉林地经过各种客土混合后，促进了N从枯落物和有机质矿化分解进入土壤的过程，但却会对有机c进入土壤产生抑制作用；（3）所有不同针阔叶树种林地经土壤客土混合后，对原有土壤的酸碱性起到中和的作用，即原来的阔叶林地土壤向偏酸性方向发展，而原来的针叶林地土壤向偏碱性方向发展；（4）所有不同树种林地的客土混合对枯落叶分解均具有明显的促进作用；（5）连香树林地的LM0．15—0．50和LY0．15—0．35、糙皮桦林地的HM0．15和HY0．15—0．50、云南松林地的ML0．15—0．50和MH0．35—0．50、云杉林地的YL0．35—0．50和YH0．35类型是相对较好的选择，可作为确定更新树种和混交比例的参考。

Long-term management of planted pure forest will lead to continuous planting obstacle and influence the sustainable development of forest. The best solution is to form mixed forest through introducing other regenerated tree species. In order to direct the option of mixed tree species and ratios on upper reach of Minjiang river, situ incubations of soil mixture （soil of coniferous forest with deciduous） of typical forests of Cercidiphyllum japonicum, Betula utilis, Pinus yunnartsirtsis and Picea asperata were carried out and the interspecific relationships of different tree species were studied through analyzing the influences of soil mixing of different forests on the biochemical characteristics and litter decomposition, according to the comparison of practical biochemical indexes of mixed soil with its theoretical predicted value （weighted average of soil mixture）. The results can be concluded as following： （1） In forestlands of C .japonicum, P. yunnansinsis and P. asperata, soil enzyme activities of urease, sucrase and catalase were intensified after mixing their soil with others. Whereas, in forestland of B. utilis, all the three soil enzyme activities were reduced after mixing with soil of P. yunnansinsis, but enzyme activities of urease and eatalase were intensified and enzyme activity of suerase was reduced after mixing with soil of P. asperata. （2） In forestlands of C . japonicum and P. yunnansinsis, the contents of organic-C and total N in soil were increased after mixing their soil with others. Whereas, in forest]and of B. utilis and P. asperata, the contents of N in soil were increased while contents of organic-C were decreased after mixing their soil with others. （3） In all forestlands of the 4 tree species, the acidities or alkalinity of soil were neutralized after mixing their soil with others. This means that soil of deciduous forest develops forward to acidity while soil of coniferous forest develops forward to alkalinity. （4） In all forestlands of the 4 tree species, the rapids of litter decomposition were advanced after mixing their soil with others. （5） According to the comprehensive effects of soil mixing, LM 0.15 -0.50 and LY 0.15 -0.35 in forestland of C. japonicum, HM 0.15 and HY 0.15 -0.50 in forestland of B. utilis, ML 0.15 -0.50 and MH 0.35 - 0. 50 in forestland of P. yunnansinsis, YL 0.35 -0.50and YH 0.35 in forestland of P. asperata are better choice for soil mixing relatively, which can be taken as reference in decision of regenerated tree species and mixing ratio of forest in practice.