| Biological invasion is a hot topic of current research, and community invasibility is the core of the study of biological invasion. Many scholars attempted to study the relationship between community invasibility and the invasion of invasive species, but most of scholars tended to consider just a factor, such as species diversity or community disturbance, etc., as the reflection of community susceptibility. However, the community invasibility was impacted by a series of biological and ecological processes, such as species diversity, the role of outside interference, environmental factors, etc., every of which could be the dominant impact factor on the community invasibility in different habitats. Therefore, studying the relationship between stability of community and the invasion of invasive species, with considering every major factors, could comprehensively understand the correlation between the community invasibility and the invasion of invasive species. Therefore, employing methods of sampling and statistical data processing, this paper evaluated the stability of the southwest karst habitat, studyed the impact of the main environmental factors and the habitat stability on Eupatorium odoratum population, and discussed the variation of the basic characteristics of Eupatorium odoratum population, including fractal structure, age structure, survivorship curves and ratio of the number of plant seedling and plant cloning in different stability habitats.The results are as follows:Based on the concept of community stability and referencing the evaluating index of stability in other relating literatures, we selected community height, coverage of local species, local species diversity, soil moisture, soil fertility reflected by soil organic matter and available N, P, K, human disturbance, six aspects of nine stability evaluateing index as the index system which could well describe community stability characteristics, and used the methods of principal components analysis and grey relational analysis which can evaluate the weight of every factor objectively, to analysis and evaluate the stability of southwest karst habitats comprehensively. The results showed that: Cephalomappa sinensis+ Bischofia polycarpa -Drypetes perreticulata- Ophiopogon dracaenoides community, Cleistanthus sumatranus- Excentrodendron hsienmu- Gymnostachyum subrosulatum community, Bischofia polycarpa- Callicarpa longifolia- Microstegium fasciculatum community and so on had higher stability index, reflecting higher stability of communities. Eupatorium odoratum+ Pueraria phaseoloides community, Trigonostemon lutescens+ litsea glutinosa- Eupatorium odoratum community, Zenia insignis + Melia azedarach - Eupatorium odoratum community and so on had lower stability index, reflecting lower stability of communities.According to stability of the classification formula, Cephalomappa sinensis+ Bischofia polycarpa- Drypetes perreticulata- Ophiopogon dracaenoides community and other seven communities were classifyed in the high stability level of communities; Melia azedarach+ Zenia insignis-Mallotus japonicus- Microstegium fasciculatum+ Eupatorium odoratum community and other three communities were classifyed in the middle stability level of communities; Eupatorium odoratum+ Pueraria phaseoloides community, Trigonostemon lutescens+ litsea glutinosa- Eupatorium odoratum community and other thirteen communities were classifyed in poor stability level of communities.Correlative software was used to analyze the data to get the relation between the main environmental factors, the habitat stability and the invasion of Eupatorium odoratum. The results showed that: coverage of local species, community height, community stability, and aircraft grass cover and abundance were significantly and negatively correlated with coverage, abundance of Eupatorium odoratum, indicating that these factors can significantly impact the invasion of Eupatorium odoratum, and perhaps light was the dominant factor and limiting factor affecting the growth of Eupatorium odoratum. Local species diversity was also negatively correlated with coverage, abundance of Eupatorium odoratum, indicating that high local species diversity can resist the invasion of Eupatorium odoratum effectively. Human disturbance had remarkable correlation with the coverage, abundance of Eupatorium odoratum, It suggested that disturbance could promote the invasion of Eupatorium odoratum. Soil available nitrogen, organic matter content and soil moisture had remarkable negative relation with the coverage, abundance of Eupatorium odoratum, with the possible reason that fertilizer and water of communities were negatively correlated with light dominant factor affecting the growth of Eupatorium odoratum.In the paper the fractal characters of Eupatorium odoratum population were studied in different types of stability communities by boxing-counting dimension and information dimension. The results showed that, the fractal characters of of Eupatorium odoratum population patterns variated with the changes of community stability. Boxing-counting dimension and information dimension were both lower, reflecting low spatial occupation abilities and weak individual spatial distributions of Eupatorium odoratum populations in high stability habitats. Boxing-counting dimension were higher or lower, which reflected the variation status degree of Eupatorium odoratum populations in the fierce competition, and lower information dimension of Eupatorium odoratum populations discloseed weak scale degree of populations pattern intensity and lower evenness of individual distribution in middle type of stability habitats. Boxing-counting dimension were higher, reflecting higher spatial occupation degrees, and information dimension were higher or lower, implying the more development of community succession, the weaker scale degree of pattern intensity of Eupatorium odoratum populations in low type of stability habitats.This paper analysed the age structure, survival curves and time-series prediction of Eupatorium odoratum population in different types of stability communities. The results showed that: Age structures of Eupatorium odoratum population were different in different types of stability habitats. Eupatorium odoratum populations were in declining and the population survival curve closed to the type of Deeveyâ… in high stability habitats. Eupatorium odoratum populations were in growing and survival curves were the types of Deeveyâ…¢or closed to the types of Deeveyâ…¡in most of low and middle stability communities. The invasion time sequence model predicts that once the Eupatorium odoratum population invade and made a stble lives in a community, it will harm the community seriously with plenty of young and mature individuals which are more adapt to habitats.Analyzing the variation of ratios of plant seedling and plant cloning number and the changes of reproductive strategies of Eupatorium odoratum population, we founded that: Eupatorium odoratum adopted different reproductive strategies in different types of stability habitats. Eupatorium odoratum mainly adopted clonal reproduction to maintain the survival and development of population in high and middle stability habitats. Eupatorium odoratum mainly used seed propagation to seek the expansion of population, or adopted seeds and reproductive strategies to seek population stability and development in less stable habitats.When taking measures to prevent Eupatorium odoratum biologically,we recommend that we should both consider the biological and ecological characteristics of Eupatorium odoratum and the susceptibility of communities, that is to say that ,we should reduce the interference of the communities and increase local species coverage and diversity to increase community stability, and to enhance the resilience of communities; When clearing of Eupatorium odoratum, we should plant local fast-growing plants to accelerate the process of community succession, to improve the stability of communities, and to prevent and control the invasion of Eupatorium odoratum.
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