陕西省油松混交林木质残体储量与腐烂特征

木质残体是油松针阔混交林的重要组成部分,具有多种的生态功能,对生态系统的稳定和发展有着不可忽视的作用。以陕西省黄龙山林区为研究区域,设置1 hm2(100 m×100 m)的固定样地,研究典型油松针阔混交林木质残体的储量组成、优势树种的空间关系、腐烂特征及密度与含水量,研究结果表明:(1)研究区油松针阔混交林内木质残体的总储量为10.73 t·hm–2,倒木是林分内木质残体的主要来源。在径级组成结构上,径级20 cm以上的木质残体储量占总储量的绝大部分。腐烂等级中,以腐烂等级Ⅱ与腐烂等级Ⅲ的木质残体贮量最多;(2)利用线性模型模拟该林分木质残体的分解密度与含水量,其拟合结果显示木质残体的密度随着腐烂等级的增加而呈现下降趋势,而含水量则随着腐烂等级的增加而呈现升高的趋势;(3)林分内主要研究树种(油松、白桦和山杨)之间在小空间尺度上呈负关联,大尺度下呈正关联,顶级树种与先锋树种间达到互利共生,群落具有较大稳定性。林分内种间竞争的结果将为地带性顶级树种油松代替白桦与山杨等先锋树种。天然油松针阔混交林木质残体的贮量组成及腐烂特征反映了该区森林群落演替后期阶段木质残体的结构特征,本文的研究结果为我国黄土高原针阔混交林生态系统的管理和保护以及可持续经营提供科学依据。

STORAGE AND DECAY CHARACTERISTICS OF WOODY DEBRIS IN PINUS TABULAEFORMIS MIXED STANDS

Woody debris (WD), mainlyincluding coarse woody debris and fine woody debris, was an important part with a variety of ecological functions in natural Pinus tabulaeformis mixed stands, which cannot be neglected effect on stability and development of the forest ecosystem. In this paper, a permanent sample plot (100 m×100 m) was set up on Huanglong Mountain of Loess Plateau, and conducted the survey and coordinate positioning for each timber based on spatial-temporal method and the point pattern analysis method. The author studied the storage composition, Inter-and interspecies spatial associations, decay characteristics, density and water content dynamics in natural Pinus tabulaeformis mixed stands, and discussed the trend of dominant species distribution, then provided reference for sustainable management of related forest. The results showed that, (1) The total storage of woody debris was 10.73 t·hm^-2, with 10.31 t·hm^-2 and 0.42 t·hm^-2 for the coarse woody debris and the fine woody debris, accounting for 96.09% and 13.91% of the total storage, respectively. The fallen wood was the main source of woody debris. The highest proportion were between 20-30 cm and 30-40 cm in diameter class, which were the absolute advantage in the number of diameter distribution, and the diameter greater than 20 cm accounted the majority of the total storage. According to the decay level, most of woody debris were focused on decay level Ⅱ and Ⅲ (the sum accounted for 69.98% and 73.49%, respectively); (2) Using the Linear model to simulate the decomposition density and water content of woody debris, the fitting results showed that the density of wood debris increased with a decline trend of decomposition level but, it showed the upward trend with the increasing with decay level for the water content; (3) The main species contained Pinus tabulaeformis, Birch and Aspen were changed from negative in small spatial scale to positive association in large spatial scale, and shared the environment resources in the end, so the forest communities had greater stability. The Inter-and interspecies spatial associations of woody debris were the results of long term interactions between the community and the natural environment, the forest ecological environment changed from positive pioneer species adaptation to shade tree species adaptation. The situation of woody debris in this forest reflected the structural characteristics of woody debris in late succession stage of the region, and the results would provide the scientific basis for forest management and ecosystems protection for Huanglong Mountain of Loess Plateau.