重庆四面山杉木林优势种群径级结构与空间分布格局

种群空间格局分析有利于更好地理解格局形成的潜在生态过程。本研究以重庆四面山杉木林为研究对象,采用单变量和双变量函数分析了样地中杉木林主要种群的空间分布格局以及种群间的空间关联性。结果表明:(1)四面山杉木林共调查到乔木65种、灌木31种、草本20种。杉木种群径级结构呈衰退型,表现为以大树为主,中树次之,无小树;腺萼马银花、元江栲、细枝柃等种群径级结构呈增长型,表现为以小树、中树为主,大树次之。(2)在0~25 m尺度内,杉木种群呈随机分布,栲和元江栲呈聚集分布,而腺萼马银花、细枝柃、光叶山矾和长蕊杜鹃等4个种群则在小尺度下呈聚集分布,随着尺度的增大,呈现出随机分布的趋势。(3)生物学特性以及生境因子的差异导致杉木林主要种群间空间关联差异较大,杉木与元江栲和腺萼马银花种群之间呈负相关,而与光叶山矾、栲和长蕊杜鹃种群呈无相关,因此,在该区杉木纯林的近自然改造上,应优先考虑竞争力强的乡土树种,如长蕊杜鹃、栲、光叶山矾等进行混交。

SIZE STRUTURE AND SPATIAL DISTRIBUTION OF CUNNINGHAMIA LANCEOLATA POPULATIONS IN CHONGQING SIMIAN MOUNTAINOUS

Point pattern analysis of species in a community is important for gaining a better understanding of the underlying ecological processes controlling the observed structure. In this paper, univariate and bivariate spatial point pattern analysis based on the pair-correlation function were used to evaluate the spatial patterns and associations of Cunninghamia lanceolat in Chongqing Simian Mountains. We found that:(1) There were 65 tree species, 31 shrub species and 20 herb species in the study plot. The population of Cunninghamia lanceolat was declining. The mature individuals were dominant, middle-aged were second in Cunninghamia lanceolat species and no young individuals; The young and middle-aged individuals were dominant, no mature individuals in Rhododendron bachii、,Castanopsis orthacantha and Castanopsis fargesii, these population were increasing. (2) At the 0-25 meter scale, the population of Cunninghamia lanceolat showed a random distribution, Castanopsis fargesii and Castanopsis orthacantha exhibited a clumped distribution, while the individuals of Rhododendron bachii, Eurya loquaiana, Symplocos lancifolia and Rhododendron stamineum were significantly clustered and as the scale increased, the distribution became random. (3) Because of biological properties and habitat factors, there was a big difference of spatial association between the main species. Cunninghamia lanceolat showed negative associations with Castanopsis orthacantha and Rhododendron bachii, but no associations with Rhododendron stamineum, Castanopsis fargesii and Symplocos lancifolia. So Rhododendron stamineum,、Castanopsis fargesii and Symplocos lancifolia should be given priority in near-natural reform of pure Cunninghamia lanceolat forest.