Litter Decomposition Driven By Soil Microarthropods And Its Effects On Soil Carbon,Nitrogen And Phosphorus In Desert Shrub Microhabitats

In grassland ecosystems,litter decomposition is an important process of soil element turnover and mineral nutrient cycling,as well as releasing mineral nutrients for plant growth.With the accumulation and decomposition of litter on the ground,nutrients and other substances in litter are gradually returned into the soil.A series of changes occur in soil chemical processes and biological processes,which plays implicaitons fro material cycling and energy flow of ecosystems.Litter arthropods play important role in litter decomposition and thus in soil carbon,nitrogen and phosphorus for ecological restoration of degraded grassland.The present study was to probe into the decomposition process of Lespedeza potaninii litter using litter bags in Caragana korshinskii shrub microhabitats in desert steppe ecosystems.The contribution of litter arthropods to litter mass loss and changes in carbon,nitrogen and phosphorus contents,and their effects on soil C,N,P content and stoichiometrical attributes were examined.The aim is to provide theoretical basis for the restoration,management and utilization of desert steppe ecosystem.The main research results were found as below:(1)Along with decomposition time,the mass loss rates of L.potaninii litter was greater at first stage and then being low at latter stage;the mass loss of litter gradually was lowest at decomposition time of 48 months.Litter arthropods played important role in the mass loss of litter.There was little difference in the release of litter C,N and P between both shrub microhabitats.As a whole,litter C content was at a state of release,and litter N content was at a state of release to enrichment and to release,and litter P content was at a state of release to enrichment;Litter C/N decreased gradually,litter C/P and N/P indicated a unimodal trend.(2)The abundance and group richness of litter arthropods was greater beneath shrub canopy than in open spaces.The diversity index of litter arthropods was significantly greater beneath shrub canopy than in open spaces at the decomposition timing of 44 and 60 months.The contribution rate of litter arthropods to litter decomposition beneanth shrub canopy was positive when it decomposed at the timing of 48 months,and the resting stage of litter decomposition was negative.The contribution rate of litter arthropods on decomposition in open spaces indicated a unimodal trend along with litter decomposition process.Litter arthropods improved litter element release after 48 months of decomposition.The contents of litter C,N and P were significantly affected by litter arthropods.(3)In the process of litter decomposition,soil C and P,and soil C/P showed little change during decomposition process.Soil N was at a state of enrichment to release and to enrichment,and soil C/N indicated a unimodal trend,and soil N/P indicated a valley trend,with maximum at the decomposition timing of 44 months.Soil C/N was mainly affected by litter N,C/N,and N/P.Soil N and P,and soil C/N and N/P were significantly affected by litter P beneath shrub canopy.Soil N and soil N/P were significantly affected by litter N and C/N in open spaces.It was suggested that the release of different nutrient elements by litter arthropods during litter decomposition was significant in shrub canopy,particularly in the release of litter C and N.The input of litter can improve soil nitrogen and phosphorus content.It is conducive for the input of litter P element into soil in the microhabitats beneath shrub canopy,while it is conducive for the input of litter N element into soil in open space.The source of soil N was mainly the litter decomposition alone.