Study Of Machilus And Phoebe Communities In Yongshun, Hunan

Yongshun county is located in western Hunan Province, the northern part of the Xiangxi Tujia and Miao autonomous prefecture. According to the division of China vegetation, Yongshun belongs to south Asia strip of evergreen broad-leaved forest in the middle subtropics; and its climate vegetation is evergreen broad-leaved forest. Yongshun has a larger area of natural forests, with the characteristics of rich species, diverse forest types. Three communities whose dominant species are Machilus lichuanensis, Machilus ichangensis and Phoebe bournei, are the most unique and special forest types, and deserve studying well. This paper discusses and studies the following aspects of Machilus and Phoebe communities in Yongshun:the flora of community, the characteristics of community, the ecological features and so on. The results of the study are as follows:1. The Machilus and Phoebe communities Yongshun have four important characteristics, that is, (1) the rarity of the communities, (2) the richness of the made-up species, (3) the frangibility of the ecological environment, and (4) the stability of the communities.2. The investigation and analysis showed that, in the eight Machilus and Phoebe community sample lands, there are 404 species of vascular plants, belonging to 118 families,279 genera. The flora characteristic shows that there are both tropical elements and temperate elements, and it also reflect obvious subtropical flora characteristics of Wuling Mountain.3. The analysis of amount features and structure characteristics of Machilus and Phoebe forests find that in the communities, Machilus and Phoebe occupies an absolute advantageous position, and its importance value takes the first place, which is much larger than other species in the community.4. The spatial patterns of Machilus and Phoebe population in the community are random. Machilus and Phoebe population has no obvious correlation with other populations. Machilus and Phoebe population shows large niche width themselves, high niche similarity proportion among other populations, small fluctuation of niche overlap with other populations, high degree of the use of resources, and better adaptability to local environment. All of those reflect that Machilus and Phoebe population has a wide distribution and a good ability to adapt to the environment.5. Machilus and Phoebe forests has the rich species diversity and nice stability, and its population age structure basically is pyramid-type. Machilus and Phoebe communities belong to growth-type, with the capability of self-regulation, self-renewal, self-improvement.6. Machilus and Phoebe communities which lie at an altitude of 300-800m, distribute in the mid hillside, lower valley, or steep slope areas. There are many bare rocks; soil is loose and moist; humus layer is thick; and soil fertility is high. The relationship between Machilus and Phoebe community and altitude is that the growth and development of Machilus and Phoebe will be affected to some extent as the altitude changes. At the altitude of 600m, the average height and diameter of Machilus and Phoebe population reach the maximum, where it also grows well and strong.7. Studies on the succession stage, succession degree, succession law of the Machilus and Phoebe communities, demonstrate that Machilus and Phoebe communities are a kind of stable one, with a high succession degree. And they are also one of the local climax communities in Yongshun.