Community Characteristics Of Carabid Beetle And Its Response To Environmental Factors Within Grassland In Ningxia

Grasslands are one of the most important components of natural ecosystems.Under the influence of global climate change,grasslands are experiencing large-scale desertification,degradation and salinization,which have attracted the attention of global ecologists,especially the biodiversity of grassland ecosystems has received widespread attention.Carabidae insects are the most diverse and numerous taxa in grassland ecosystems,and are also natural enemies of important pests in agriculture and forestry,characterized by predatory nature.Therefore,the study of grassland habitats on the composition,diversity,spatial distribution and response to environmental factors can help to understand the function of grassland ecosystems and provide scientific reference for grassland biodiversity conservation and restoration,as well as grassland management and restoration.A virtual grid of 300m×300m was used to set up and code the sampling points with GPS in three steppe habitats:desert steppe,typical steppe and meadow steppe in Ningxia.In each sample point area,20m×20m sample squares were set up,and the carabid beetle was investigated and sampled by pitfall traps.We investigated the vegetation,soil and climate factors in the study area to understand the relationship between vegetation,soil and climate factors and carabid beetle;Measured the functional traits,and compared the differences in the functional traits of the carabid beetle and its response to environmental factors in different study areas;Investigated the spatial factors in the study area to clarify the spatial distribution of the carabid beetle species richness and its environmental interpretation.The main findings are as follows.(1)A total of 9776 individuals were captured,belonging to 12 genera and 26 species.The results showed that the number of individuals of Carabus glyptoterus was 1193,accounting for 13.59%,and it was the dominant species in desert steppe;the number of individuals of Carabus vladimirsky was 2825,accounting for 28.89%,and it was the dominant species in typical steppe and meadow steppe;the small phytophagous carabid beetle were mainly found in desert steppe,and the predators were concentrated in typical steppe and meadow grassland.Pseudotaphoxenus mongolicus,Cymindis binotata and Carabus glyptoterus are the indicator species in desert steppe.Poecillus gebler,Carabus culptipennis,Pseudotaphoxenus rugipennis are typical steppe indicator;Carabus crassesculptus,Reflexisphodrus reflexipennis,Carabus modestulus have a strong indicator role for meadow steppe.(2)The Hill number interpolation and extrapolation curves based on sample size and coverage were used to assess the diversity of steppe beetles in different steppe.The results showed that species richness was the richest in typical steppe and the least in desert steppe,but could not reflect the significant variability of steppe species richness among the three steppes;The Shannon diversity index was the highest in meadow steppe and the lowest in desert steppe;the evenness was the highest in desert steppe,while was the lowest in meadow steppe.The functional richness,functional dispersion,and Rao Q entropy index of carabid beetles were the highest in desert steppe,and function of evenness was the highest in typical steppe.(3)Based on redundantly analyzing the correlations between carabid beetle and environmental factors,it can be concluded that the abundance of carabid beetle is closely related to the value of soil pH,plant coverage and annual precipitation in typical steppe,but plant coverage,annual precipitation and soil temperature are the main driving factors;while plant coverage,the value of soil pH and soil temperature are closely related carabid beetle but the factors driving the abundance of carabid beetle are soil temperature,plant coverage,annual temperature and the value of soil.The environmental factors that were closely related to the indicator carabid beetle were vegetation factors rather than soil factors.(4)The carabid beetle in desert steppe was long and heavy,and small and light in meadow steppe and typical steppe;Four corner analysis showed that functional traits were positively correlated with soil temperature and soil pH,and negatively correlated with plant richness,plant coverage,and total soil phosphorus.(5)There was a significant difference between the spatial distribution of beetle richness and influence factors.The main factor driving the spatial distribution of carabid beetle was precipitation(q=0.677)based on geographic detector method,and the interactions among environmental factors all mutually enhanced the influence on the spatial distribution of carabid beetle,while the main factors influencing the spatial distribution were annual mean maximum temperature,soil temperature and annual precipitation.The hierarchical partitioning and variance decomposition showed that climate factor was the main factor influencing the spatial distribution pattern of beetle in desert steppe,the spatial variables in typical steppe and the soil factors in meadow steppe.The risk area of carabid beetle distribution is located in desert steppe and the northern part of meadow steppe.In summary,carabid beetle plays an important role in the diversity of grassland system.There were significant differences in maintaining carabid beetle’s diversity among different steppe types.The highest species richness was found in typical steppe,which indicates that typical steppe plays an important role in the conservation of carabid beetles.Functional traits,on the other hand,provide a better analysis of carabid beetle community composition at the functional level and contribute to a better understanding of the response of carabid beetle to environmental changes,thus maintaining the functional diversity of carabid beetle communities at a large scale and exploiting their potential biocontrol potential.