摘要:依据研究区5种典型人工林近自然状况，以人工生态公益林的近自然经营管理为目标，提出林分结构调整策略与方法。主要从林分结构、物种组成、年龄及枯死木几个方面考虑选取了垂直结构、水平结构、草本盖度及其多样性、天然更新、物种多样性、组成系数、直径分布、枯木比例、健康木比例10个指标，应用基于单位圆的π值法则，采取定性与定量相结合的方法，对5种林分的近自然状态做出评价并依据评价结果提出相应改造措施。青海云杉-白桦混交林（ω_PB=0.4786）属于远近自然林分，此类林分在密度合理的情况下无需过多人为抚育；青杨-白桦混交林（ω_BP=0.2664）属于近人工林，此类林分以伐除病虫害严重的青杨、调整密度和补植青海云杉为主；青海云杉-青杨混交林（ω_PP=0.2283）属于近人工林，此类林分以伐除病虫害严重的青杨、调整密度和补植白桦为主；青海云杉-落叶松混交林（ω_PL=0.1872）属于人工林，此类林分以调整密度和补植白桦为主；青海云杉纯林（ω_P=0.0190）属于人工林，此类林分以调整密度和营造杉桦混交林为主。通过近自然度评价与分析，为当地近自然经营提供了直观可靠的依据。在进行林分结构调整时，首先通过伐除干扰木来调整林分密度，其次要营造针阔混交林分，其中以青海云杉和白桦混交林为主要目标林分。



Abstract:At present, although large-scale forest land has been restored and exploited in China through a large number of artificial afforestation, the tree species of the plantation are simple and the structure law,it has caused many ecosystem problems such as pests and diseases, soil fertility decline, etc. Therefore, ensuring the sustainable development of forests through near-natural management is of great significance. Near-natural forest stands can effectively resist natural disasters and pests, optimize soil physical and chemical properties, increase biodiversity, and improve the ecological and economic benefits of forests. Through the evaluation of near-naturalness, we can understand the actual growth status of the stand and construct a near-natural evaluation system that conforms to the conditions of the local site conditions, thus providing a reliable basis for near-natural management. According to the natural conditions of five typical plantation forests in the eastern part of Qinghai province, this paper aims at the near-natural management of plantation ecological public forests and tries to put forward the stand structure adjustment strategies and methods. The vertical structure, horizontal structure, herb coverage and its diversity, natural regeneration, species diversity, composition coefficient, diameter distribution, ratio of dead wood, and healthy wood are mainly selected from the aspects of stand structure, species composition, age and dead wood. Based on the combination of qualitative description and quantitative analysis, the near-natural unit circle π-value rule was applied to evaluate the natural characteristics of five typical forest stands and propose corresponding reform measures based on the evaluation results. Picea crassifolia-Betula platyphylla mixed forest (ω_PB=0.4786) is a far from nature forest. Such forests do not need too much artificial rearing under reasonable density. Populus cathayana-Betula platyphylla mixed forest (ω_BP=0.2664) is near plantation forest. In this kind of stand, the main activities are to cut down the Populus cathayana infested with insect pests, adjust the density and replant Picea crassifolia. Picea crassifolia-Populus cathayana mixed forest (ω_PP=0.2283) is near plantation forest. This kind of stand is mainly to cut off the Populus cathayana with serious disease and insect pest, adjust the density, and replant Betula platyphylla. Picea crassifolia-Larix principis-rupprechtii mixed forest (ω_PL=0.1872) is plantation forest. This type of stand is mainly to adjust density and replant Betula platyphylla. Picea crassifolia forest (ω_P=0.0190) is plantation forest. This type of stand is mainly for adjusting density and constructing Picea crassifolia-Betula platyphylla mixed forests. Through the evaluation and analysis of the near-natural condition, it provides a direct and reliable basis for local near-natural management. The method to adjust the stand structure is to first adjust the stand density by removing disturbing trees, and then create a mixed forest of coniferous and broad-leaved trees, among which Picea crassifolia-Betula platyphylla mixed forest is the main one.





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