摘要
岷江冷杉 (Abiesfaxoniana)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 10 0m× 6 0m。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 .33m ;幼树 :H≥ 0 .33m ,且DBH(胸径 ) <2 .5cm ;小树 :2 .5cm≤DBH <7.5cm ;中树 :7.5cm≤DBH <2 2 .5cm和大树 :DBH≥ 2 2 .5cm。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 (SP PA) (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 2 17·hm-2 和 2 6 83·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1m× 1m到 30m× 30m)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?
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 (I δ), 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 t
出处
《植物生态学报》
CAS
CSCD
北大核心
2004年第3期341-350,共10页
Chinese Journal of Plant Ecology
基金
"Ninth_five"keystoneitemofCAS (KZ95 2_S1_10 4)
keystoneitemofNationalNaturalScienceFoundationofChina( 3 9893 3 60 )
keystoneitemofThreeGorgesConstructiveCommitteeofStateDepartment(SX2 0 0 1_0 0 3 )
importantresearchfielditeminknowledgecreativep
