辽宁西部地区油松水土保持纯林改造与评价

辽宁省西部营造有大量用于水土保持的油松人工纯林。如何改造这些低效的纯林是生产实践中面临的一个严重问题。根据近自然林业思想,通过实践提出了带状皆伐栽植阔叶树,块状皆伐栽植阔叶树和林中空地、林缘等栽植阔叶树改造现有的油松纯林具体方法。论述了改造的对象和树种选择等问题,并详细介绍了每种方法的关键技术及其应用条件。通过实际调查和对比分析,对经过带状改造的油松林进行了评价。结果表明,16年后,采用上述方法改造的油松林具有明显的分层结构,林下植物物种多样性增加了23．5％-52．9％,土壤脲酶、磷酸酶和蔗糖酶活性比对照分别提高了6％-142％,46％-99％和31％-200％,松毛虫危害得到有效控制,水土保持功能也得到提高。图2表3参37。

Transformation and assessment of Chinese pine pure plantations for soil and water conservation in western Liaoning Province,P. R. China

Western Liaoning Province is characterized by huge areas of lowly-efficient Chinese pine (Pinus tabulaeformis Carr.) pure plantations. How to transform these plantations has become an increasingly significant management problem. In this study, the authors summarized the approaches, which are based on close-to-nature silvicultural system, to transform the pure pine plantations. Native broadleaved trees were planted in three methods: 1) after strip clearcutting, 2) after patch clearcutting; 3) on the open forestland and the forest edge. The transformation targets and the selection of tree species were expatiated in this paper. The key techniques and their application conditions for each method were analyzed and discussed. Through investigation and contrastive analysis, the assessment was made to the stands transformed by strip method. Results showed that the mixed stands at 16 years after transformation had an obvious layered structure and the species richness of understorey vegetation increased by 23.5%-52.9%. Soil enzyme activities of urease, phosphatase and sucrase increased by 6%-142%, 46%-99% and 31%-200%, respectively. Moreover, the transformed stands could effectively control the occurrence of pine caterpillars in plantations. Consequently the transformations enhanced the function of soil and water conservation.