云冷杉过伐林垂直结构特征分析

目的]以云冷杉过伐林为研究对象,综合分析其在垂直层次上的结构特征,进一步探索云冷杉过伐林的生长过程、演替规律,更加准确和全面地认识云冷杉过伐林的状态和发展趋势,从而为合理地制定和调整针对过伐林的经营措施提供理论依据。方法]基于12块面积1hm~2的标准地数据,首先,采用定量的树冠光竞争高法划分林层,将林分从垂直层次上划分为上林层、中林层和下林层;其次,在垂直结构的基础上,进行林分结构特征分析,包括各林层的直径分布、树种组成、树种隔离程度、竞争以及分布格局。结果]表明:(1)以树冠光竞争高度法划分的林层分层效果较好,各林层树冠光竞争高、平均胸径和蓄积量均在0.01水平上差异极显著;(2)随林层高度的增加直径分布由反"J"形分布转变为左偏单峰状分布,中林层和上林层峰值差别较大;(3)各林层树种构成差异不大,但下林层中针叶树种蓄积比重偏低;(4)上林层更有可能出现较高的混交度,不同树种随林层高度的增加其混交度的变化趋势有所差异;(5)随林层高度的增加,林分平均竞争压力逐渐减小,各树种竞争压力随林层的变化趋势与各林层总体平均变化趋势基本一致;在不同林层,不同生长习性的树种竞争差异明显;(6)各林层多呈聚集和随机分布,上林层更有可能出现随机分布,而下林层更有可能出现聚集分布。结论]综合分析可知研究区的林分结构相对稳定,处于由过伐林向原始林恢复演替的进程中。垂直结构定量化的方法能更加全面的认识和描述过伐林的结构现状及未来的发展方向,研究结果可为长白山地区过伐林的可持续经营提供参考。

Analysis of Vertical Structure Characteristics for Spruce-Fir Over-cutting Forest

Objective] To further understand the status and development tendency of spruce-fir over-cutting forest more by quantitative analysis of the vertical structure characteristics for spruce-fir over-cutting forest in Jin''gouling Forest Farm of Jilin Province.Method] Based on the 12 Spruce-fir over-cutting forest sample plots with area of 1 hm², the stands were divided into upper, middle and lower layers according to the canopy competition height (CCH) in stand. Each layer was used to analyze the distribution of diameter at breast height (DBH), the species composition, the segregation, the competition and the distribution pattern by the investigation data. Result] (1) The effect of the CCH method is reasonable. The CCH, the mean DBH and the volume showed extremely significant difference at 0.01 levels. (2) The diameter distribution shifted from the reverse "J" shape distribution to left-skewed unimodal distribution with the increase of the height of storey. The difference of peaks between upper and middle layer was great. (3) The difference of tree species composition in each layer was little, but the proportion of volume of the coniferous species in the lower layer was on the low side. (4) The upper layer was more likely to be higher on the mingling, and the variation tendency of mingling was different with the increase of the forest storey for different tree species. (5) The average competition pressure of the forest storey decreased gradually with the increase of the forest storey, and the variation tendency of the competition pressures of the tree species with the changes of forest stories was basically consistent with the overall average change trend. But in different forest storeys, the species with different growth habits had different competitiveness. (6) Most of the forest storey followed the aggregative and randomly distribution, the upper layer was more likely to occur in a random distribution, and the lower layer was more likely to occur in an aggregation distribution. Conclusion] Based on the comprehensive analysis, it is find that the stand is still in the progress of restoration succession. By this method it is enable for us to more comprehensively understand and describe the status and future development direction of the over-cutting forest structure, which can provide a reference for the sustainable management of over-cutting forest in Changbaishan Mountain area of China.