川西北冷杉林恢复过程中土壤动物群落动态

为了掌握川西北冷杉林群落恢复过程中土壤动物群落的变化动态,2008年4月对川西北地区的原始冷杉林和50a冷杉林的土壤动物群落进行了调查。共捕获大型土壤动物287个,33科(类);中小型土壤动物4681个,57科(类)。50a冷杉林大型土壤动物群落的类群数和密度显著高于原始冷杉林(P<0.05);中小型土壤动物群落的类群数和密度分别显著低于(P<0.05)和高于原始林(P<0.05)。PCA排序结果表明两个不同年龄段间的大型和中小型土壤动物群落结构均存在明显差异,但大型土壤动物群落间的相似性系数小于中小型土壤动物群落,表明大型土壤动物群落的恢复速度慢于中小型土壤动物群落;且大型和中小型土壤动物群落间的Srenson相似性均低于Morisita-Horn相似性,进一步表明群落物种组成的恢复速度较慢,而优势类群及常见类群的数量恢复较快。50a冷杉林的大型和中小型土壤动物的多样性指数H、丰富度指数D和优势度指数C均高于原始冷杉林,而均匀度指数E则低于原始冷杉林,但仅大型土壤动物的丰富度指数D存在显著差异(P<0.05)。以上研究结果表明,冷杉林的恢复过程可显著提高大型土壤动物群落多样性,且土壤动物群落的组成恢复较慢,而优势类群和常见类群的个体数量恢复较快。

Changes of soil faunal communities during the restoration progress of Abies faxoniana Forests in Northwestern Sichuan

Abies faxoniana forests create a zone of vegetation in the northwestern Sichuan alpine valley area and are important ecologically and as a center of biodiversity. This zone is sensitive to global climate change and is located in the eastern portion of the Qinghai-Tibet Plateau and the upper reaches of Yangtze River. After long-term extensive logging on a broad scale, the extent of these forests has been greatly reduced and the forests themselves degraded. More recently, forest restoration and regeneration are being emphasized in the region including old growth natural forests, plantation forests and natural secondary forests. Wolong Nature Reserve and Miyaluo Forest District were selected as an area to study soil faunal dynamics during the restoration of A. faxoniana forests. The study was conducted in old-growth A. faxoniana forest (OAFF) and 50-year-old A. faxoniana forest (50AFF) in April 2008. This study was conducted in northwestern Sichuan Province (27°57'-34°21'N, 97°26'-104°27'E), China. A total of 287 soil macrofauna individuals and 4681 soil meso-microfauna individuals, belonging to 33 and 57 families, respectively, were collected during the study. Three dominant groups, the Doratodesmidae, Paradoxosomatidae and Curculionidae, accounted for 62.02% of the soil macrofauna individuals. Nematoda dominated the soil meso-microfauna, accounting for 81.01% of the individuals. The number of taxonomic groups and the individual density of soil macrofauna in the 50AFF were significantly higher than those of the OAFF (P<0.05). The number of taxonomic groups of soil meso-microfauna in the 50AFF were significantly lower and the individual density was significantly higher than those of the OAFF (P<0.05). PCA ordination suggests the community structures of the two soil macrofauna communities were more different than those of the soil meso-microfauna communities. The similarities between the two soil macrofauna communities were lower than those of soil meso-microfauna, and the values of the Sørenson Index were lower than those of the Morisita-Horn Index. This implies the recovery rate is slower for the soil macrofauna than the soil meso-microfauna, and the restorative process has a relatively stronger influence on the taxonomic compositions of the soil macrofauna community than on the individual densities of the dominant and common taxonomic groups. Several ecological indices, such as species richness, abundance, and a diversity index, were analyzed. The Shannon (H), Margalef (D) and Simpson (C) indices of soil meso-microfauna communities in 50AFF were higher and the Pielou Index (E) was lower than that of the OAFF. But a significant difference (P<0.05) between the two soil macrofauna communities was only recorded with the Margalef Index (D). Correlation analysis suggests the group number and mean density of the soil macrofauna were remarkably positively correlated with organic matter content (P<0.05); the group number was remarkably positively correlated with litter depth content, but was also markedly negatively correlation with total N content (P<0.05). The group number and mean density of the soil meso-microfauna were only positively correlated with soil bulk density content (P<0.05). All results above showed the restoration of A. faxoniana forests can significantly improve soil macrofauna diversity; the taxonomic composition of the soil fauna community recovered slowly, but the individuals of the dominant and common taxonomic groups recovered rapidly.