林分拥挤度及其应用

林分密度的量化表达及其合理密度的确定已成为森林经营的关键科学问题。林分平均冠幅是对林木光合作用面积大小的直接反映,林木平均距离则体现了林木最大空间利用的可能性,而林分密度是影响这两个重要指标大小的直接原因。本文以林木平均距离和冠幅为基础,提出了林分拥挤度(K)的数字化表达方法。林分拥挤度用来表达林木拥挤在一起的程度,用林木平均距离与平均冠幅的比值表示。该指标清晰直观地表达了林分中林木间的拥挤程度——K值越小,林木间越拥挤,能有效反映林分生长过程中林木拥挤程度及其动态变化特征。该指标的合理标准区间为0.9,1.1],并用长期造林密度试验数据进行了论证。该指数是对林分密度更为直观科学的表达,具有简单易操作的优点,可用于评价森林是否需要经营及确定首次间伐时间与经营强度,最终为密度控制与调节提供依据。 

Stand crowding degree and its application

Expressing stand density quantitatively and determining its reasonable density are key scientific issues in forest management. Based on the forest mean crown width of trees, which directly reflects forest area of photosynthesis, and mean tree distance, which reflects the possibility of forest maximum spatial utility , both are influenced by stand density, a new index K, which is equal to the ratio of mean distance and crown width is proposed to digitally express the stand crowding degree. The value of K can directly and clearly reflect the crowding degree of trees, and the smaller the value is,the more crowded the trees are. It can also effectively reflect the congestion degree and its dynamic feature in the stand growing process. The reasonable interval of K value ranges from 0. 9 to 1. 1, and it is proven by the long-term planting density experiment data. The index K, which has the advantage of simple and easy to operate, is a more direct and scientific expression of stand density. It can be used to evaluate whether the forest needs management, and determine the right time for the first thinning and its management intensity. Eventually, it provides the basis for density control and adjustment.