| Biological invasion is causing the local species extinction, making the important reasons for the loss of biodiversity. Eichhirnia crasslpes invasion in worldwide bring huge ecological and economic loss. its introduction about eight decades ago, water hyacinth has infested many water bodies across almost half of China's territory, causing a decline of native biodiversity, alteration of ecosystem services and deterioration of aquatic environments. Eichhirnia crasslpes is not only floating plants and is famous invasive species in the world ranking of malignant intrusion weeds.This article through to hainan island Eichhirnia crasslpes invasion of common areas of investigation, Eichhirnia crasslpes invasion of ecological system characteristics and genetic variation is analyzed, the results show that:(1) Eichhirnia crasslpe on Hainan Island ecosystem invasion of habitat types in accordance with lettuce into the river, marshes, ponds, paddy fields lost shortage, five types of aquatic wasteland. Environment of the invasion, according to the invasion intensity points, lost shortage paddy> ponds> aquatic wasteland> river> swamp.(2) Eichhirnia crasslpes invasion of ecosystems, vegetation for pure plant more plexus, mostly for one or two year or the perennial herbaceous plants, the total 91.04%accounted for. This community composition, aerial parts not canopy closure to receive invasive species violation, the invasion in suitable conditions of airspace settled, ecological niches.(3) Vegetation types could be divided into 11 formations with quantitative classification method. Analysis from the species composition, The characteristics of Eichhirnia crasslpes invasion of community is:①Opening plant communities, mixed herbs constitute extremely simple community.②Performance for invasive species is symbiotic coordinated invasion in community. Community gradually simple.(4) The distribution of Eichhirnia crasslpe, TN in the range of 0.29～4.3mg/L; TP in the range of 0.02～0.39mg/L; YK within the range of 1.4～8.1mg/L; BOD5 in the range of 9～33mg/L; CODCr in the range 0.5～9mg/L; pH in the range of 6.05～7.79. After the invasion of water is the typical feature of water BOD5/CODcr the emergence of a high percentage of the value.(5) Invasion of habitat species distribution and environmental factors that correlation analysis (CCA) chemical factor analysis:TN,TP,TK and BOD5 is the key factor for Eichhirnia crasslpes invasion of water. After successful invasion water, the high ratio of BOD5/CODcr. can explain eutrophication of water environment toward the direction development trend. Aquatic environment the emergence of this feature, reflects the habitat community on the water invasion adaptation to the environment by vegetation, habitat material circulation in the transformation of the environment.(6) Under different habitats Eichhirnia crasslpes analysis of genetic diversity (ISSR markers) show that the Eichhirnia crasslpes in Hainan island in different habitats, did not appear genetic differentiation. Although in different habitats there is some difference in morphology, but there arc no difference. Hainan island of different habitats Eichhirnia crasslpes under the same genetic background, the produce genetic drift genetic variation is unlikely, even if there are a few variations, also often failed to test it out. So, mainly by-asexual reproduction Eichhirnia crasslpes adapt and successfully invaded different habitat types, did not produce genetic differentiation.(7) Under the control of the existing conditions of the invasion of the wild on Hainan Island, Eichhirnia crasslpes need to control the spread of pollution sources, as much as possible reduce the possibility of eutrophication in the water flowing through the basin, through rainfall runoff, convergence, seepage is not Increase the degree of eutrophication, in this based on the ability to repair itself through the ecology, to maintain the relative stability of clean water. Invasive water lettuce directly reduce the availability of water resources. |
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