沙地樟子松天然林南缘分布区林木竞争、空间格局及其更新特征

以呼伦贝尔沙地樟子松地理分布南缘天然林为研究对象,采用Hegyi竞争指数与点格局等分析方法,研究了沙地樟子松天然林的种群结构、种内竞争、空间格局及幼树更新等特征。结果表明:1)所调查区域天然沙地樟子松纯林处于中幼龄阶段,属增长型种群;2)其竞争指数与对象木胸径服从幂函数关系CI=242.24D~(-1.12)(R~2=0.91);3)幼树在小尺度上呈聚集分布,中树与大树在中大尺度上呈随机分布;幼树与中树在小尺度上呈正相关性,中树与大树在小尺度呈负相关性;4)竞争指数与更新幼树和存活更新幼树的密度均呈显著正相关性。在林分管理中需要充分考虑林木竞争、空间格局以及种群更新的关系,本研究可为沙地樟子松天然林的经营管理与保护提供重要的科学依据。

Tree competition, spatial pattern, and regeneration of a Mongolian pine natural forest in the southern geographical edge

Tree growth and regeneration are influenced by many biological and non-biological factors. Among these factors, competition and point pattern analysis are important issues in ecology and forestry that affect tree growth, forest structure, and dynamics, and thus, play an important role in population regeneration and succession. Mongolian pine natural forest in China is mainly distributed in the northern Greater Khingan Mountains and sandy land of the Hulun Buir forest grassland transition zone. The southernmost edge of its geographical distribution lies at the southern Hulun Buir Sandy Land. Owing to its characteristics of cold resistance, drought resistance, and developed root system, it plays an important role in wind protection and sand fixation, farmland protection, and is also widely used in sand afforestation in northern China. There has been considerable research on the spatial pattern, competition, and renewal of Mongolian pine in China, especially on the influence of fire interference on competition, spatial pattern, and regeneration. However, research on the relationship between competition, spatial patterns, and forest regeneration of Mongolian pine natural forests is limited.This study selected Mongolian pine natural forest from the southern range of its geographical distribution to fully understand the relationship between tree competition, spatial patterns, and regeneration, and clarify the interactions of these factors. We analyzed the population structure, intraspecific competition, spatial patterns, and regeneration of saplings of Mongolian pine stands using the Hegyi single tree competition index and point pattern analysis methods. The results showed that 1) the natural stand in the investigation area was in a middle age, expanding population stage. 2) The relationship between the competition index and diameter at breast height of object trees followed the equation CI=242.24D^-1.12 (R²=0.91). 3) The saplings were spatially aggregated at small scales, and mid-and large-sized trees of the population were randomly or uniformly distributed. Saplings and mid-sized trees were significantly positively correlated, whereas mid-and large-sized trees were negatively correlated. 4) There was a significant positive correlation between the competition index and the density of saplings, as well as the survival saplings. The relationship between forest competition, spatial pattern, and population regeneration needs to be fully considered in forest management. This study can provide scientific guidance for the conservation and protection of natural forests, and construction and management of artificial forests in the future.