The Relationship Between Abundance Of Carabid Beetles And Environmental Factors Within Three Grassland Types And Management Regimes

The relationship between biodiversity and ecosystem functioning(BEF)is an important issue in current ecological research.Vegetation and soil are important environmental factors to maintain the function of grassland ecosystem,which are of great significance for biodiversity conservation.However,the differences in grassland types and management regimes will affect the relationship,and surface arthropods represented by carabids are particularly sensitive to environmental changes.Therefore,this study monitored the composition and distribution of carabids in six transects of three grassland types in Ningxia from 2017 to 2018 by using the pitfall traps.The effects of three grassland management regimes(enclosure,mowing,and grazing),and different altitudes on carabids abundance were evaluated at the transect level.The differences of carabids richness,population diversity and functional diversity within three grassland types(desert steppe,typical steppe,and meadow steppe)were quantified and analyzed at regional level.Finally,the main environmental factors driving the distribution of carabids were explored,and the response mechanism of carabids activity density and its indicative species to environmental variables was fitted,which provided theoretical basis for the regulation and control of grassland management regimes in Ningxia,enriching the stability,productivity,environmental monitoring and biodiversity conservation of grassland ecosystem.1.A total of 6873 carabids specimens were collected,belonging to 25 species from 13 genera.Carabus vladimirskyi,Poecillus gebleri and C glyptoterus were dominant species.The peak period of carabids occurrence was September(Desert steppe),August(Typical steppe)and July(Meadow grassland),?-diversity showed that carabids population and functional diversity in desert steppe were significantly lower than in typical steppe and meadow steppe.Enclosure and mowing areas were significantly higher than farming and pastoral areas.The weeds area was significantly higher than Festuca brachyphylla area.2.PCA and multiple regression showed that soil organic matter,soil total phosphorus and plant coverage were the key environmental factors affecting the activity density of carabids in typical steppe.RDA and multiple regression showed that elevation,soil total nitrogen,surface temperature and plant height were the key factors in meadow steppe.3.Carabus glyptoterus is the only indicative species in desert steppe.Carabus vladimirskyi C.vladimirskyi and P.gebleri are the indicative species in typical steppe.Carabus vladimirskyi and Poecillus fortipes are the indicative species in meadow grassland.GAM fitting curves showed that C.vladimirskyi increased with the increase of soil organic matter and total phosphorus,while C.glyptoterus decreased in typical steppe.Carabus vladimirskyi increased with the increase of altitude and soil total nitrogen,and decreased with the increase of plant height and soil temperature,and P.fortipes decreased first and then increased with the increase of altitude in the meadow grassland.