经营密度及混交对广西柳杉林分生长的影响

[目的]研究广西六万林场不同柳杉人工林经营密度及柳杉与杉木混交对柳杉林分生长的影响,为广西科学种植柳杉、合理利用森林资源提供依据.[方法]选取1450株/ha柳杉林作为对照林,2075、1800、2700株/ha柳杉林和柳杉与杉木混交林(1450株/ha)作为试验林,在各试验林分中分别设置3块标准样地,进行每木检尺,调查和分析各林分的平均树高、胸径、冠幅、单株材积及林分蓄积量.[结果]林分平均胸径、冠幅、单株材积随密度增大而逐渐减小;密度对径级的分布影响明显,密度越大,径级株数高峰期来得越早;林木蓄积量大小依次为1450株ha>2075株/ha>1800株/ha>2700株/ha;在柳杉与杉木混交林中,柳杉的各林分因子生长状况均优于纯林,与相近密度纯林(1450株/ha)相比,单株材积提高了47.3%,总蓄积量提高了32.0%.[结论]提倡以大、中径材为主要培育目的种植柳杉人工林,应选择柳杉与杉木混交的模式,可提高林分收获量,达到速生、丰产、优质的人工林经营效果.

Effects of density and mixed planting on stand growth of Cryptonmeria fortune in Guangxi

【Objective】The effects of density and mixed planting on stand growth in Guangxi Liuwan Forest Farm were studied to provide references for Cryptonmeria fortune planting and rational utilization of forestry resources in Guangxi.【Method】Five plantations were chosen， four of them were pure Cryptonmeria fortune plantations with the densities of 1450，1800，2075 and 2700 trees/ha，respectively，the other one was the plantation mixed Cryptonmeria fortune and Cunningham （7∶3） with the density of 1430 trees/ha. Average height， diameter at breast height （DBH）， canopy， individual volume and stand stock of the chosen three sampling plots in each plantation were investigated and analyzed. 【Result】Average DBH， canopy， height/diameter and individual volume tended to decrease with the increasing density. The densities showed obvious effect on distribution of DBH， the larger the density， the earlier DBH class peak. The stand stock for the four pure Cryptonmeria fortune plantations followed the trend：1450 trees/ha>2075 trees/ha>1800 trees/ha>2700 trees/ha. All the stand factors of growth in the mixed plantation were superior to that in any pure plantation. Compared to the pure plantation with similar density （1450 trees/ha）， the individual volume increased by 47.3% and the stand stock increased by 32.0% in mixed plantation. 【Conclusion】Mixed plantation of Cryptonmeria fortune and Cunningham is recommended to boost forest productivity.