Study On Functional Traits Of Dominant Plants And Community Biodiversity In Desert Steppe

The loss of biodiversity on a global scale has made biodiversity and ecosystem functions a research hotspot.The steppe has the functions of water conservation,wind and sand fixation,soil and water conservation,and maintenance of biological diversity.However,in recent years,due to climate change and human disturbance,biodiversity and productivity have decreased,and the area of degradation has been increasing,which seriously threatens ecological security.In this study,using vegetation surveys and correlation analysis methods,the dynamic characteristics of species diversity in desert steppe,dynamic characteristics and adaptation strategies of dominant plant functional traits,and the relationship between biological diversity and functional diversity were analyzed by the degraded grassland of desert steppe in Yanchi County,Ningxia.The main conclusions are as follows:(1)During the whole growing season,the species richness,Simpson index,Shannon-wiener index,and Pielou index of the plant communities in the plots as a whole were plot 3>plot 1>plot 2,and the functional groups of plant communities in all plots took the perennial grasses as the most important value.The important values of each functional group in Sample 1 fluctuated during the year,and the important value of perennial grasses was greater than that of other functional groups,occupying an advantageous position;The important values of functional group n plot 2 were perennial grasses>perennial weeds>half shrubs>perennial legumes>annual weeds,and perennial grasses and perennial weeds dominated;The important value of perennial grasses was the highest in plot 3,and the important values of perennial grasses,perennial weeds,semi-shrubs,and perennial legumes all showed a"decline-rise-decline" trend.In another,there was a compensation effect between perennial weeds and perennial grasses in plot 1,perennial weeds and perennial grasses in plot 2 and perennial weeds and semi-shrubs in plot 3.(2)The dominant plant traits and leaf traits of the three plots showed obvious and different changes during the growing season,reflecting the adaptability of functional traits under different phylogenetic backgrounds.At the overall level,the specific leaf area and leaf N content of dominant plants in plot 1 showed a significant positive correlation(P<0.01),and the crown size of dominant plants in plot 2 had a significant negative correlation with leaf dry matter content(P<0.05),and the dry matter content of the three plots were negatively related to the specific leaf area;leaf N content,leaf C content,and leaf dry matter content were the main functional traits that affect different dominant plant growth processes.All in all,desert plants have smaller specific leaf area and larger leaf dry matter content helpful for reducing the combination of transpiration and nutrient storage,which may be the main survival strategy for adapting to arid and desert environment.(3)The functional uniformity,functional separation,and functional dispersion of the dominant plants in the three plots were all represented as plot 3>plot 1>plot 2 and functional richness as plot 1>plot 3>plot 2.The correlation between function richness and Simpson index,Shannon-wiener index and Pielou index was strong,and the correlation between function separation and Simpson index and Pielou index was strong.The correlation between functional richness and species richness,Simpson index,Shannon-wiener index and Pielou index was not strong in plot 2,and the correlation between functional separation and Simpson index,Shannon-wiener index and Pielou was strong.The correlation between functional richness and Pielou index in plot 3 was strong,while the correlation with species richness,Simpson index and Shannon-wiener index was weak.And the correlation between functional separation and Shannon-wiener index and Pielou index was strong.(4)Species diversity,functional diversity,and the relationship between the two behave differently in plant communities in desert steppe.Therefore,when studying the ecological function of the degraded grassland in the desert,we should also explore the functional diversity closely related to species diversity and ecological functions in addition to measuring the traditional species diversity.