岷江冷杉(Abies faxoniana)是青藏高原东缘亚高山顶极森林植被的优势种之一，主要分布于岷江、大渡河和白龙江的上游地区。该文研究了岷江冷杉天然原始群落的种群结构和空间分布格局。样方大小为100 m ×60 m。测定了所有个体的坐标及其胸径、高度和冠幅。将岷江冷杉按大小级分为5级，即幼苗：H（高度）<0.33 m； 幼树: H≥0.33 m, 且 DBH（胸径）<2.5 cm； 小树: 2.5 cm≤DBH<7.5 cm； 中树: 7.5 cm≤DBH <22.5 cm和大树: DBH≥22.5 cm。采用了Morisita 指数 (Iδ)、方差均值比 (V/m), 聚块度指标(m*/m)和空间点格局分析方法 (SPPA) (采用了Ripley二次分析法)4种方法分析岷江冷杉的空间分布格局。结果表明： 1) 岷江冷杉种群结构稳定。因为其年龄结构表现为增长型， 幼苗幼树储备丰富，密度分别为2 217·hm-2和2 683·hm-2，可见岷江冷杉天然更新良好，进而通过其“移动镶嵌循环”更新维持其种群的稳定性。在大小级结构图中的一些缺刻和年龄结构图中的“断代”现象，是干扰的时空异质性在采样的时间和空间断面上的反映。 2) 幼苗、幼树和小树在所有的研究尺度（从 1 m×1m 到 30 m×30 m）下都呈聚集分布。但中树和大树基本上呈随机分布。3) 聚集强度随尺度的变化而变化。上述的前3种方法表明，聚集强度随尺度的增加而减弱。但是，空间点格局分析法表明，岷江冷杉幼苗、幼树和小树的聚集强度首先随尺度的增加而增强，达到一定高峰后，随尺度的增加而减弱。 4) 岷江冷杉的空间分布格局是它与其自然环境长期作用的结果，同时也反映了其种群天然更新的格局和机制。 5) 4种分析方法对格局的判别基本一致, 但空间点格局分析法更能反映出格局强度随尺度的变化的关系，是值得推荐的一种分析空间分布格局的方法。使用空间点格局分析法的限制主要在于其计算和采样比较复杂。另外，由于Ripley 二次分析法对于“空白”的探测不敏感，需要进一步做一些方法上的改进。
Minjiang fir (Abies faxoniana) (MJF) is a dominant tree species of sub-alpine forests on the eastern edge of Qinghai-Tibetan Plateau, and is mainly distributed over the upper reaches of the Minjiang, Dadu and Bailong Rivers. The population structure and spatial pattern of MJF was studied in a naturally occurring stand. In a 100 m×60 m plot, the location of every tree was mapped, and the diameter at breast height (DBH), height and canopy area of each individual recorded. Trees were divided into five size classes: seedlings, height <0.33 m; saplings, height ≥ 0.33 m, and DBH<2.5 cm; small trees, 2.5 cm ≤ DBH<7.5 cm; medium Trees, 7.5 cm ≤ DBH <22.5 cm; and big trees, DBH ≥ 22.5 cm. The spatial pattern of MJF was analyzed using four independent methods: the Morisita index (Iδ), variance to mean ratio (V/m), the congregation index (m*/m) and the spatial point pattern analysis (SPPA) (Ripley‘s second-order- analysis method). The results revealed that MJF was a stable population with an inverse J-shaped size structure indicating good natural regeneration. Seedlings and saplings were very abundant, with densities of 2 217·hm-2 and 2 683·hm-2, respectively. Irregularities in the size structure histogram reflected past disturbances. The spatial analyses revealed that seedlings, saplings and small trees were clumped at most spatial scales studied which ranged from 1 m to 30 m, whereas the medium-sized trees and big trees were randomly distributed. The intensity of assemblage (IA) varied with scale. The first three methods indicated that IA decreased with increasing scale, but the SPPA method showed that the IA of seedlings, saplings and small trees first increased with increasing scale, and then declined at greater scales. We conclude that the spatial pattern of MJF in this subalpine forest resulted from long-term interactions between the MJF and its natural environment and mechanisms of natural regeneration that vary among species. The four different methods were very similar on the whole in their abilities to discriminate spatial patterns, but SPPA was superior in its ability to detect changes of IA with scale. Thus, we recommend SPPA for analyzing spatial patterns of populations. However, a limitation to using SPPA relates to the complexity of sampling and calculation requised and some refinements in Ripley‘s second-order-analysis are needed in order to better as it detect gaps.