基于间伐调整的湖南楠木次生林结构化经营技术

Structure-based management technology of Phoebe zhennan secondary forest in Hunan province based on thinning adjustment

以湖南省一类清查样地为基础数据,用全混交度、大小比数、角尺度、竞争指数等空间结构指标作为建模变量,采用乘除法基本思想构建楠木次生林结构目标函数,通过林分相容性收获预估模型拟合结果来确定各年龄阶段林分最适断面积,将最适断面积作为确定间伐量的约束指标,构建湖南省楠木次生林结构化经营模型,通过间伐调整,提出楠木次生林结构化经营技术,促进森林提质增量。以3470号样地为例,进行结构化经营模拟。根据优化模型确定间伐木共23株,株数间伐强度为16.3%,经营后林分树种空间隔离程度增加,全混交度由原来的0.365增加到0.395,林木所受的竞争压力大幅减小,其竞争指数在原来的基础上减小了51.4%,林分空间分布格局趋近于随机分布。通过对林分未来10年生长进行预测,将林分断面积调整到最适状态时断面积、蓄积定期生长量均高于未间伐林分以及较低密度林分。说明本次经营活动在对林分结构进行改善的同时林分生长活力也有所提高,经营措施可行,可为湖南地区楠木次生林提质增量提供科学依据。

Based on forest resource continuous investigation data from Hunan province,some spatial structure indexes including full mixing degree,size ratio,angle scale and competition index were used as modeling variables,the multi-objective structured management model was established using the methods of multiplication and division,the optimal growth of stands was determined by the model of compatible harvesting and used as thinning constraint,through the thinning adjustment,in order to put forward structure management technology of Phoebe Zhennan secondary forest and improve the quality of forest.This paper carried on the structural management simulation with sample No.3470 as an example.According to the optimized model,a total of 23 trees were cut down,and the thinning intensity was 16.3%.After the adjustment,the spatial isolation degree of tree species increased,the compete mingling increased from 0.365 to 0.395,the competition pressure on trees decreased significantly and the competition index decreased by 51.4%,the spatial distribution pattern of stand was closed to random distribution.The basal area and volume of stand were higher than those without thinning and lower density in the ten years according to the prediction of stand growth.The results showed that the management activities improved structure and vigor of the stand,the measures were feasible,which could provide a scientific basis for the improvement of Phoebe zhennan secondary forest quality in Hunan province.