紫椴次生林枯立木与活立木数量及空间结构特征分析

Characteristics analysis of quantity and spatial structure of standing live and dead trees in Tilia amurensis secondary forest on the west slope of Zhangguangcailing,northeastern China

【目的】通过分析两种干扰模式(未择伐、择伐)下紫椴次生林中枯立木和活立木的数量及空间结构特征,探究林分生长状态、演替过程以及枯立木形成的主要原因,为紫椴次生林的生长、保护以及经营提供依据。【方法】分析活立木、枯立木物种组成、径级结构、高度级结构及空间结构。【结果】(1)在择伐林分中,紫椴和色木槭以及其他活立木占优势地位的树种在枯立木中也同样占优势地位,而未择伐林分中,紫椴在活立木和枯立木中占优势,但色木槭只在活立木中占优势,枯立木中并不多见。(2)两个林分中小径阶的活立木和枯立木均占优势,径阶结构均大致呈倒J型。两个林分活立木高度级结构大致呈左偏山峰状,而枯立木大致呈倒J型,小个体枯立木所占比例较大,因此可以分析出两个林分枯立木形成主要的原因是林木间竞争。(3)由空间结构参数三元分析可知,两个林分中呈随机分布、高度混交且占优势的活立木较多。而大多数枯立木处于随机分布、劣势状态,且周围林木均为其他树种或仅有1株为同树种。(4)通过枯立木结构参数四元分布可知,两个林分枯立木总体呈现随机分布,具有很强的种间混交,且大小分化很明显。四元分布能反映出该状态下的枯立木周围存在3~4株活立木。【结论】以上信息进一步说明林木种间竞争是该种林分枯立木形成的主要原因。该研究分析了2种紫椴次生林活立木及枯立木空间结构及数量特征,不仅可以探究该类型次生林枯立木形成的主要原因,也为其保护和经营提供了理论依据。

[Objective] The aim of this study was to provide a basis for the growth, protection and management of Tilia amurensis secondary forest by analyzing the quantity and spatial structure characteristics of standing live and dead trees and exploring the growth state, succession process and the main causes of standing dead trees under two disturbance modes(non-cutting and selective cutting).[Method] The research was conducted by analyzing the species composition, diameter structure, height structure and spatial structure of standing live and dead trees. [Result](1) Tilia amurensis, Acer mono, as well as other dominant tree species in living trees also had a dominant position in dead trees in selective cutting stand, while only Tilia amurensis was dominate among the living trees and standing dead trees in non-cutting stand, but Acer mono was only dominate in the living trees, and it was rare in dead standing trees.(2) The standing live and dead trees of the small diameter were dominant in all two stands, and the diameter distribution was roughly inverted J type. The height class distribution of living trees was roughly left-skewed distribution in two stands, while the standing dead trees were inverted J type, meanwhile, the small standing dead trees accounted for a large proportion. Therefore, it could be analyzed that the main reason for the formation of dead trees in the two stands was the competition among trees.(3) The trivariate distribution of spatial structure parameters had shown that there were more dominant living trees, which were randomly distributed, highly mixed and dominant in two stands. Whereas, most of the standing dead trees were randomly distributed, in disadvantaged state, and the surrounding trees were all other tree species or only one was the same tree species.(4) The quadrivariate distribution of spatial structure parameters showed that the standing dead trees of the two stands were randomly distributed in general with good mixture of species and obvious size differentiation. There were three or four standing live trees around one standing dead trees in that state. [Conclusion] It further indicates that inter-species competition is the main reason for the formation of standing dead trees. This study analyzed the spatial structure and quantitative characteristics of standing live and dead trees in the secondary forest of Tilia amurensis. Therefore it is not only exploring the formation of dead standing trees in the secondary forest, but also provides a theoretical basis for its protection and management.