| The reduction of plant diversity in Lake wetland has become a thorny problem in the world.It is imminent to discuss the interrelated,differential distribution,influencing factors and management measures of wetland plants on the ecosystem scale.In this paper,the aquatic plants and habitat factors of 79 plots and 580 quadrats were investigated in the Caohai wetland of Heqing by route method,transect method and sample method.Diversity index was used to measure species diversity,bi-directional indicator species(TWINSPAN)was used to classify wetland plant communities.The relationship between major species distribution and environmental factors was analyzed by canonical correspondence analysis(CCA).Spearman rank correlation coefficient,Chi square test,and cluster analysis were used to identify interspecies and divide ecological species.The distribution pattern of aquatic plants on the sample scale was analyzed.The results are as follows.(1)There are 43 species of aquatic plants belonging to 32 genera and 21 families in Heqing Caohai wetland.The composition of ecological types is more balanced,37.21%of the total water plant,39.53% for the tquite water plant,11.63% for floating plants,11.63% for floating plants,86.05% in the local species and six for exotic plants(including 1 invasive species),with only seven species in the wild species.It indicates that the aquatic plants in Caohai wetland of Heqing are localized and have obvious biochemical characteristics.(2)Heqing Caohai wetland plant community is complex and diverse.TWINSPAN classification divided the aquatic plants into 17 clusters.Among them,the dominant group of seaweed,Zizania,Phragmites australis,wild rhombohedral and cauliflower was dominant.The results of CCA sequencing showed that the main environmental factors affecting the species(community)distribution were management intensity,while water depth and transparency had less influence,and the depth of sediment had no effect.(3)The species richness and Shannon-wiener index of different tubular wetlands showed the same regularity that the highest species richness was found in the Westerngrass sea,the lowest in Moon Bay and the medium in the Longtan and the East Grass sea.However,The Simpson index has the opposite trend.Odditionally,The Highest Pielou index was found in the Moon Bay,the lowest in Longtan,the medium of the West Caohai and the East Caohai.(4)In the chi square test,the perfect significant(P < 0.01)or significant(0.01<P <0.05)positive and negative connection pairs are 42 and 48 respectively,and 25 pairs are connected,and the negative connection is 381 pairs.The Spearman rank correlation coefficient showed that 41 species pairs,51 species pairs,20 species pairs were positively correlated,and the 384 species were negatively correlated.(5)Two groups were identified when RDCC equaled to 15 or 20 respectively.When RDCC=10,five groups were identified: first groups are the main species of Longtan;the second group is the same species of each wetland;the third group is the dominant species of Moon Bay;the fourth group is the dominant species of wetland water plant;the fifth group is the dominant species of floating leaf plants in the West grass sea.(6)On the scale of the sample belt,the environmental factors of the vertical lakeside have obvious gradient changes,but most of the samples with water depth,transparency and sediment depth have no obvious gradient law.The variety of plant species and quantity is related to other factors such as interspecific relationship and resource competition.To sum up,There are abundant aquatic plants in Caohai wetland of Heqing.The community structure and organization level were relatively high.The intensity of management and protection was the main factor affecting the species diversity and distribution pattern of wetland plants,while the distribution pattern of aquatic plants on the sample scale was mainly influenced by interspecific effects,and the interspecific effect of wetland dominant aquatic plants which is quite strong. |
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