Plant Community Under The Influence Of Ecological Water Transport In The Lower Tarim River Evaluation Of Ecological Characteristics And Restoration Effects

In order to solve the problem of ecological degradation in the lower reaches of the Tarim River and prevent the complete decline of the desert plant communities around the river channel,as of 2019,a total of 19 ecological water transfer tasks have been carried out in the lower reaches of the Tarim River.This is of great significance for saving fragile ecosystems.Environmental conditions and the impact of water transfer tasks,the water head arrival area,the water consumption in different sections,and the degree of degradation of the original study area are different,resulting in different degrees of ecological water transfer in different areas.According to the different degrees of degradation in each study area,four research areas,namely Yingsu,Kaerdayi,Alagan,and Yiganbujima,were selected to study the species diversity,community stability,interspecific relationships,distribution patterns,and ecology of plant communities.The characteristics of the site differentiation and the coexistence mechanism are discussed,and the similarities and differences between the ecological characteristics and restoration status of plant communities affected by the different degrees of ecological water transport are summarized,which provides a theoretical basis for ecological restoration in the lower reaches of the Tarim River.The results show:(1)There was a peak of species diversity in Yingsu at a distance of about 250 m from the river,and then the response to ecological water transport gradually decreased;the impact of ecological water transport on Kaerdayi was wide,Shannon within 500 m from the river-Weiner index is between 1 and 1.5,and the species diversity after 500 m shows a significant decline trend;the species diversity of Alagan is higher within 100 m from the river,and then gradually declines and gradually gets rid of the water transport.The role of species diversity is uplifted;the dryness of the cannabis is less affected by water transport,and the response of species diversity to water transport is not obvious,and its characteristics are more caused by the constraints of local environmental conditions.The peak value of the diversity of different research areas in the range of 0?250 m from the river channel is:Yingsu>Alagan>Kaerdayi>Yiganbujima;the peak of species diversity in the range of 250?700 m from the river The size is expressed as:Kaerdayi>Yingsu>Yiganbujima>Alagan.The distribution of the species in the four study areas was relatively uniform and the characteristics were similar.The Pielou evenness index was about 0.5 to 1.0.According to the measurement results of ? diversity of species and their ecological significance,the comparison results of the overall species diversity in each study area are:Alagan>Kaerdayi>Yiganbujima>Yingsu.(2)The stability of the plant community was determined as follows:Yingsu>Kaerdayi>Yiganjima>Alagan,all did not reach a stable level.There is no mature functional group formed in the plant community.There are differences in the asynchronous growth and development time of each species' response to the construction of the community and the environment after filtering through the environment.(3)The interspecific relationship of vegetation in the lower reaches of the Tarim River is not significant,and the distribution is loose,and it is more inclined to be distributed independently.The structure of the community is unstable,and the dependence between species pairs in the same plot is not strong.There are plaque distribution in plant communities,but the species are relatively single.The number of negativelyconnected species pairs is higher than the number of positive-associated species pairs in the three crosssections of the plant communities in Kaerdayi,Alagan,and Yiganbujima.It proves that there is a certain degree of competition and exclusivity among species in these three regions,but it not does not have a high significance.According to the characteristics of interspecific association,the existing population can be divided into three ecological species groups.(4)The environmental stress under drought conditions affects the spatial distribution of species,and the plant population is mostly in a distributed pattern.Environmental filtration is the main reason for the formation of the current species coexistence mechanism.Based on the niche width characteristics of plant populations in each study area,The order of species' competition ability to resources is:shrubs>trees>herbs.The niche overlap index indicates that there is a more general competition relationship in the community.The intensity of inter-species competition is higher than that of intra-species,but the intensity of competition is not fierce and subject to drought stress.The ecological adaptability of the plant population after filtering with the environment is small,and there is a situation of shared resource levels and long-term coexistence.(5)The succession degree of the plant communities in Yingsu was higher,followed by Kaerdayi.Alagan and Yiganbujima officinalis are at the early stage of plant community development,and Yiganbujima officinalis has been filtered by the environment,enabling stable succession,while the plant community of Alagan is in the state of environmental filtration,and the population in this area will continue Dynamic changes occur.Based on the above conclusions,the restoration effect of the plant community under the influence of ecological water transport in the lower reaches of the Tarim River is funnel-shaped,starting from the Daxihaizi Reservoir,and gradually decreasing towards Taitema Lake.