Spatial structure optimal of Larix gmelinii plantation

  Objective  Taking the Larix gmelinii plantation in Xiaoxing’an Mountains of northeastern China as the research object, based on the spatial structure parameters and management density table of the stand, the cutting intensity and logging were determined, the spatial structure of stand was optimized, and the effects of optimization were analyzed to provide theoretical basis for the optimization of the spatial structure of the plantation.

  Method  In Nancha County, Yichun City of Heilongjiang Province, four fixed sample plots of Larix gmelinii plantation with an area of 0.2 ha were set up. The angle scale, size ratio, competition index and opening ratio of the commonly used stand spatial structure parameters were selected, and the spatial structure evaluation index was constructed. The cutting intensity and cutting wood were determined by combining the management density table of Larix gmelinii, and the spatial structure changes before and after thinning were analyzed.

  Result  The forest trees in the sample plot belong to the cluster distribution, random distribution and uniform distribution. There were many medium and small diameter trees, which were in a disadvantaged state. The growth space of the trees was in a serious and insufficient state, and the forest competition pressure was relatively high. The evaluation grades were all level 2. According to the management density table, the monitoring sample plot 2 and monitoring sample plot 4 were harvested. The harvesting plant number intensity was 20.7% and 12.7%, respectively. After harvesting, the angular scale decreased by 3.9% and increased by 3.8%, and the size ratio decreased by 0.5% and 0.4%, respectively. The competition index decreased by 16.8% and 5.2%, the openness ratio increased by 24.5% and 4.2%, and the spatial structure evaluation index increased by 27.8% and 7.2%, respectively.

  Conclusion  Using stand spatial structure parameters combined with management density table for thinning can effectively improve stand spatial structure, improve the growth space and dominant degree of trees, and reduce the competitive pressure.