中文摘要：

谷地云冷杉林是小兴安岭地区谷地的顶极群落,在我国温带植被类型中占有重要地位.本研究基于凉水谷地云冷杉林9.12 hm2动态监测样地,分析了群落物种组成和径级结构,并运用点格局方法分析16个主要物种不同生活史阶段的空间分布格局,探讨密度制约效应在优势种不同生活史阶段所发挥的作用.结果表明：（1）样地内木本植物共有44种,胸径？1 cm的独立个体35656株,隶属于14科29属;（2）林冠层、林下层树种和优势种冷杉与红皮云杉的径级分布均呈倒＂J＂型,灌木层的径级分布呈＂L＂型;（3）主要物种幼树Ⅰ（1 cm？胸径〈5 cm）在1~50 m尺度上主要呈现聚集分布,随着尺度增大,聚集强度逐渐减小;幼树Ⅱ（5 cm？胸径〈10 cm）随着尺度增大呈现出由聚集分布向随机分布变化;成年树（胸径？10 cm）则呈近似随机分布或均匀分布;（4）优势种冷杉幼树Ⅰ和幼树Ⅱ与成年树利用生境的方式均不同,而红皮云杉幼树Ⅰ与成年树利用生境的方式不同,幼树Ⅱ与成年树利用生境的方式相同;冷杉与红皮云杉的幼树Ⅰ与幼树Ⅱ均在1~50 m尺度上呈现相对于成年树额外的聚集,在尺度〉5 m时,随着径级增大,这种额外的聚集逐渐减小,说明密度制约效应起作用.

英文摘要：

Spruce-fir forest climax communities in the valleys of the Xiao Hinggan mountains represent an important zonal vegetation common in the temperate forests of northeastern China. Using a dynamic 9.12 ha spruce-fir valley forest plot in Liangshui National Natural Reserve, we analyzed species composition, diameter at breast height （DBH） size class distribution, and spatial patterns of species distribution for 16 major species. We also investigated density-dependent effects at different life history stages of dominant species. We documented 44 woody species （35656 individuals）, belonging to 14 families and 29 genera. The DBH distribution of individuals for canopy and understory of two dominant species generally showed a distribution. Saplings of major species had a clumped distribution across reverse ＂J＂ type distribution. Shrubs exhibited an ＂L＂ type a scale of 1-50 m, while aggregation intensity decreased as scale increased. The aggregation of juveniles shifted from a clumped to a random distribution as scale increased. Adults exhibited random or uniform distributions. Case-control analysis of dominant species revealed that Abies nephrolepis saplings and juveniles exploit their habitat in a different manner compared with adults. Picea koraiensis saplings exploited the available habitat differently to adult individuals, with juveniles behaving in a similar manner as adults. A. nephrolepis and P. koraiensis saplings and juveniles were more clustered compared with adults; this clustering declined with increasing size class suggesting the occurrence of density- dependent thinning.