Effect Of Litter Decomposition Of Caragana Korshinskii On Litter Arthropod Community

To mitigate desertification and land degradation,the afforestation by native shrub Caragana korshinskii is often used as one of the most effective ways to attain ecological recovery in semiarid and arid desertified ecosystems.These shrub litter can thus shape the trophic structure within arthropod community and extend the food chain,and maintain the complexity and stability of fragile grassland ecosystems.Litter arthropod is sensitive to environmental changes.The abundance,richness,and diversity of litter arthropod are determined by the availability of soil microhabitat and food resources.Hence,the change in environmental properties and food resources caused by the decomposition of C.korshinskii litter will have significantly effect on the composition and diversity distribution of litter arthropod.Understanding the effects of decomposition of shrub litter on the abundance,richness,and diversity distribution of litter arthropod across semiarid and arid sites could be conducive to biological diversity conservation and associated grassland ecosystem functioning under future climatic changes.Using the litterbag method,we determine the decomposition rate and nutrient elements of litter,and investigated the composition and diversity of litter arthropod during litter decomposition in the semi-arid desertified grassland of Yanchi County and the arid desertified grassland of Urat County.The main results were as follows:(1)The decomposition process of C.korshinskii litter was affected by the shrub microhabitat and climatic factors.There were significantly higher litter decomposition rate in the shrub understory than in the open patches between shrubs at 12th months,20 months,and 24 months in Yanchi County and at 20 months in Urat County.In Yanchi County,there were significantly higher residual rate of carbon and nitrogen at 20 months only,there were significantly higher residual rate of phosphorus at 12 and 20 months,there were significantly higher residual rate of potassium at 20 and 24 months,and there were significantly higher residual rate of lignin at 12 months only in the open patches between shrubs than in the shrub understory.While in Urat County,there were no significant differences in the residual rates of carbon,nitrogen,phosphorus,and lignin between microhabitats,but after 12 months of litter decomposition,the residual rate of potassium was significantly higher in the open patches between shrubs than in the shrub understory.Soil moisture was a key factor driving the decomposition of C.korshinskii litter.(2)During litter decomposition process,in Yanchi County,there were significantly higher abundance of litter arthropod at 20 months only,and there were significantly higher richness and Shannon index of litter arthropods at 8 months,20 months,and 24 months in the shrub understory than in the open patches between shrubs.The total nitrogen and carbon of the litter,and the soil pH were the main environmental factors driving the distribution of litter arthropod.In Urat County,there were significantly higher abundance of litter arthropod at 12 months,20 months,and 24 months,and there were significantly higher richness of litter arthropods at 12 months and 24 months in the shrub understory than in the open patches between shrubs.Nevertheless,there were no significant differences in the Shannon index of litter arthropod between microhabitats.The total nitrogen of the litter and the soil moisture were the main environmental factors driving the distribution of litter arthropod.(3)In Yanchi County,during the litter decomposition process,the abundance and richness of mite were significantly higher in the shrub understory than in than in the open patches between shrubs at 20 months.Soil temperature,litter content,litter total potassium,litter total carbon,and litter total nitrogen were closely related to the distribution of mite populations.The abundance and richness of collembola were significantly higher in the shrub understory than in than in the open patches between shrubs at 20 months of decomposition.Environmental factors have little effect on the distribution of collembola populations.In Urat County,there were signigicantly higher abundance of mite at 12 months,20 months,and 24 months,and there were signigicantly higher richness of mite at 12 months and 24 months in the shrub understory than in the open patches between shrubs.The litter content,litter total phosphorus,litter total potassium,litter total nitrogen,and litter total carbon are closely related to the distribution of mite populations.The abundance and richness of collembola were significantly higher in the shrub understory than in than in the open patches between shrubs at 12 months.Soil conductivity was closely related to the distribution of collembola populations.(5)The result showed that soil moisture was a key factor driving the decomposition of C.korshinskii litter,and the shrub microhabitat will delay the decomposition process of C.korshinskii litter.During the litter decomposition process,the total nitrogen and carbon of the litter were the main environmental factors driving the distribution of litter arthropod in Yanchi County,while the total nitrogen of the litter were the main environmental factors driving the distribution of litter arthropod in Urat County.Meanwhile,under the condition of climate change,the decreased precipitation weakens the effect of litter carbon on litter arthropods.