| Through investigate the kind of alpine Rhododendron L. Sejila mountain communities, according to field survey datas, Sejila Mountain Alpine Rhododendron L.species composition of communities and the number of characteristics, species diversity index, the dominant species niche characteristics, the relationship between species were analyzed, then ,draw the following main conclusion.(1)Sejila Mountain Rhododendron L. community, was a large area located in Sejila Mount or high-altitude areas near the timberline, it is the natural vegetation . Through 16 type place's investigation, community high 0.4～1.6m, the vertical hierarchical structure is simple, may divide into the bush level, field layer obvious two, the mess, the lichen class plant is developed in the community. Alpine Rhododendron L. pant communities plant makes up 38 genera of 21 families, the species makes up 54 kinds, also there are abundant dendritic lichen, shell form lichen and liver moss in the community. Among investigating Alpine Rhododendron L. plant community that arrive, kinds of number compositae(10 kinds), secondly it is Rosaceae and Ericsceae subject (6 kinds respectively), plants of ground bud are the most, is 35.2% on average; Secondly it is short high-order bud plant and underground bud plant, accounts for 31.2% and 27.3% respectively;And the annual plant and there are less bud plants on the ground, accounts for 23.1% and 4.0% respectively .Sejila alpine mountain community and the East Qilian Mountains Rhododendron L. shrub community characteristics compared to the two families, genera, as well as the composition of the number of life forms, leaf type and leaf quality characteristics such as appearance are close to, but different species composition .Through analysis community's geographical composition, this community area is the temperate zone distribution majority, reflects the community the North temperate zone nature, but the community also has the world distribution, the pan-tropics distribution, North Pole - - mountain distributed being, this said that the brilliant Sejila Mountain alpine distribution not only has the temperate zone zonality vegetation's typical characteristic, moreover also has certain contacting with the cold temperate zone vegetation and the alpine vegetation.(2)The community species multiplicity and locates the environment by the community itself and so on many kinds of factors to synthesize the decision, because all kinds the position is different, in the community the habitat non-uniformity difference, the species multiplicity is also different. Alpine mountain habitat of a high degree of heterogeneity, different aspect, slope position, such as lots of soil thickness and light, there are differences in moisture, therefore in the plant individual is been not similarly big the microhabitat influence, the habitat non-uniformity difference is obvious, have greater influence on distribution and growth of the species.Adopt of evenness, Simpson, Shannon-Winner, Patrick richness, Hill and other index Sejila Mountain alpine Rhododendron L.a diversity of communities, communities in all sorts of species richness and species diversity index showed an overall index of herb layer > the characteristics of shrub layer or the characteristics of shrub layer > herb layer, caused the field layer plant's change to be big to the high and cold cuckoo community species multiple index influences, the community bush level multiple index movements were not big, but the field layer multiple index movements were big, the explanation cuckoo's was strong in its community competitive power. Looking from the entire community species abundance and the species multiple indices, the same slope to the species multiplicity and the species abundance change is not big, is close, but the shady side and the sunny slope change is actually various, this constructs group aspects and so on kind, microhabitat, community's degree of cover, shade density with the cuckoo community to have the relations.(3)Niche similar to the proportion from Pianka niche overlap and the measurement results, the vast majority of species niche overlap between the values in between 0 ~ 0.6,indicate the competition among alpineRhododendron L.advantage community is not very fierce, mainly due to its community for the cold mountain Rhododendron L. mature community type, is the original vegetation, in the long-term development, in the harsh alpine environment under the pressure of the relationship between species tend to complement each other, weakening the competition, which is "survival of the fittest" is all about. Alpine mountain complex topography, different sections of different slope, slope position of the niche there are significant differences, soil coverage of non-continuity and heterogeneity, as well as changes in the complexity of the diversity of habitat led to a high degree of heterogeneity, resulting in plant Habitat characteristics of their adaptation, distribution differences emerged, some niche differentiation between species, thus reducing the inter-species niche overlap. As a whole , the dominant population determined niche: niche breadth, the greater the population, species adapt to ecological factors on the greater range in the distribution of communities within the greater rate of utilization of various resources stronger. The greater the niche overlap, populations of the greater proximity of the ecological use of resources, the higher the degree of similarity. Wide ecological niche of the population of the narrow population of the overlap may have a higher value, lower the contrary.(4)In the alpine shrub Communities, the bush makes up and plays an important role with the space structure in the plant kind of the community, Thus, the alpine shrub communities of the shrub layer of vegetation interspecific association properties to some extent, directly or indirectly, the entire community to reflect the characteristics of the structure and function. Shrub layer of species based on community values and the importance of the binary distribution of sample data, through the alpine Rhododendron L.shrub layer communities associated species analysis alpineRhododendron L.community was not generally significant positive association, a comprehensive analysis of AC coefficients,χ2 test the main populations of shrub layer showed a significant negative association that Sejila Mountain Alpine Rhododendron L.shrub layer of plant communities on a better division of resources, the relationship between the relative independence of strong communities in a variety of groups tend to appear independent. Therefore, alpine mountain Sejila Rhododendron L.symbiotic community in the role of mutual benefit or in a small-scale habitat conditions on the same type of low demand; Sejila Mountain alpine Rhododendron L.during the course of performing and taking the place of in more steady development in season.Due to objective conditions, the paper alpine Rhododendron L.communities of the study group of the original data is only based on 16 surveys based on the plot, although the populations of 11 to be generally representative of Sejila Mountain alpine Rhododendron L.basic characteristics of communities, But objectively speaking, to 16 samples to represent the whole mountain Sejila situation is still not perfect, the future need to be further supplemented. |
PDF Full Text Request