北京东灵山优势种群树木死亡对空间格局与生境的影响

森林群落动态及其与环境因子关系研究一直是生态学的重要研究内容之一,树木死亡是森林群落动态的重要环节,环境因子是树木死亡的重要影响因素,因此,开展对树木死亡及其与环境相关性研究对分析森林群落动态至关重要。以东灵山暖温带落叶阔叶次生林20 hm~2动态监测样地为研究对象,对样地优势种群树木死亡前后(死亡前:活立木;死亡后,枯立木、倒木)种群数量特征、空间分布及生境相关性的变化关系进行研究,运用点格局、物种-生境相关性分析等方法对数据进行分析。结果:(1)树木死亡前,多度排序为辽东栎黑桦山杨华北落叶松;树木死亡后,多度排序为山杨黑桦辽东栎华北落叶松;树木死亡前后,随取样尺度增大,分布模式均由聚集向随机过渡。(2)种群与生境关联性分析表明:山杨、黑桦、华北落叶松活立木随机分布,辽东栎聚集于缓坡;山杨、辽东栎枯立木缓坡分布较多,黑桦随机,华北落叶松集中于山脊;山杨、黑桦倒木陡坡较多,辽东栎集中于山脊。(3)不同种群死亡前后的空间格局有明显的尺度依赖性,同时与物种自身生物学特性、密度制约、生境过滤的过程相关。

The study of the effect of tree death on spatial pattern and habitat associations in dominant populations of Dongling Mountains in Beijing

Research on forest community dynamics and its correlation with environmental factors have been one of the important topics in ecology. Tree death is a vital aspect of forest community dynamics. Environmental factors play significant roles in tree death; therefore, the correlation between wood death and environmental factors for analysis of forest trends need to be studied. The research was performed in a 20 hm² warm temperate secondary deciduous broadleaved mixed forest dynamics plot to investigate the population quantity characteristic, spatial distribution, and the relationship of the habitat, before and after tree death (before the death:living tree stand; after death:dead tree stand and log). The data were analyzed using point pattern, species-habitat correlation. The results were as follows:(1) Before the death, Quercus mongolica > Betula dahurica > Populus davidiana > Larix principis-rupprechtii. After the death, the order was P. davidiana > B. dahurica > Q. mongolica > L. principis-rupprechtii. Before and after the death, the distribution pattern changed from aggregation to random with the increase in sampling scale. (2) The association analysis of populations and habitats showed that the living standing trees of P. davidiana, B. dahurica, L. principis-rupprechtii were randomly distributed, Q. mongolica were clustered on gentle slopes, there was a higher distribution of P. davidiana and Q. mongolica saplings on the gentle slopes, that of B. dahurica was random, and L. principis-rupprechtii was concentrated on the ridges. There were many steep slopes of fallen P. davidiana, and B. dahurica, and Q. mongolica that were concentrated on the ridge. (3) The spatial pattern of different populations before and after death, appeared to be obvious scale dependence, and were related to the biological characteristics of the species, density constraints, and the process of habitat filtration.