阴山山脉天然侧柏林的基本特征

阴山山脉是中国天然侧柏(Platycladus orientalis)林分布的西北界, 侧柏林也是阴山山脉最主要的森林群落之一。它具有较好的固坡、保土、涵养水源及改善生境的作用。为了解阴山山脉天然侧柏林种群、群落特征和空间分布规律以更好地为侧柏林的经营提供理论依据, 我们以阴山山脉大青山及乌拉山段天然侧柏林为研究对象, 通过样方调查, 分析了侧柏林的植物区系特征, 并根据群落各层片物种优势度将该区侧柏林划分为6个群丛类型, 分析了各群丛特征及其空间分布的生态序列。结果表明: (1)阴山山脉天然侧柏林群落共出现维管植物96种, 隶属于30科70属, 种的地理成分包括8个类型18个亚型, 其中东古北极分布最多, 其次为东亚分布; (2)从群落结构分析, 发育良好的侧柏群落表现为完整的乔木层和草本层, 灌木盖度普遍偏低, 基本不能成层, 在干扰较为严重的地段甚至消失; (3)各群丛侧柏的径级结构基本呈正态分布, 属于稳定的群落类型, 侧柏的平均株高随胸径的增大整体呈增长型; (4)该区侧柏林受干扰较严重, 加之严酷的生境条件, 建群种侧柏的平均胸径较小且植株分叉较多, 不适合作为用材林, 建议将其作为生态公益林及种源林加以保护利用。

Characteristics of natural Platycladus orientalis forests in the Yin Mountains of Northwest China

Natural Platycladus orientalis forests in the Yin Mountains are the northwestern boundary of natural Chinese P. orientalis forests and also one of the most important forests in the Yin Mountains, with respect to erosion prevention, soil conservation, water conservation, and habitat improvement. This study examined details about the characteristics of the population, community, and distribution of natural P. orientalis forests, to allow for better management as well as to provide a theoretical basis. Natural P. orientalis forests in Daqing Mountain and Wula Mountain were selected as the research subjects, and through quadrat investigations, were divided into 6 associations. Characteristics of the flora and the structure were analyzed. We also discussed the diameter structure of each association of P. orientalis and the distribution succession series between associations. The main results are as follows: (1) There were 96 vascular plants belonging to 70 genera of 30 families found in the natural P. orientalis forests, and the geographic components of species contained 8 types and 18 subtypes, which were mainly distributed in the East Pan-North Pole, followed by East Asia; (2) From the analysis of community structure, well-developed natural P. orientalis forests were characterized by a tree layer and herb layer, however the shrub was sensitive to interference, and coverage was generally lower in areas with more human interference, and could even disappear; (3) The diameter structure of P. orientalis followed a normal distribution which is a stable community type, and average plant height increased with the diameter overall growth model; (4) Due to strong interference and harsh habitats, the average diameter of P. orientalisis was small, and they were also more bifurcation which is not suitable for timber forests. We suggest regarding these natural P. orientalis forests as ecological and provenance forests.