The Decomposition Process Of Reaumuria Soongorica Litter And The Contribution Of Arthropod In Shrub Microhabitats In Semi-Arid And Arid Regions

In arid and semi-arid regions,Reaumuria soongorica has the characteristics of drought resistance,salinity resistance,stress resistance and sand-collecting ability.It can grow in arid environment for a long time,and it has become an extremely important plant species to maintain the stability of the fragile ecosystem of desert steppe.Due to the dual effects of climate and human disturbance,the R.soongorica woodland is severely degraded.To promote the ecological restoration of the R.soongorica woodland,the vegetation construction of Caragana korshinskii as the main plant species was carried out in the degraded area.C.korshinskii and R.are inlaid and distributed to form a compound shrubgrass system.The microenvironment formed by C.korshinskii shrubs not only affects the distribution of litter arthropods and the decomposition process of R.soongorica litter but also affects the decomposition of litter arthropods on R.soongorica litter.In this study,in semi-arid region(Yanchi,Ningxia)and arid area(Urad Rear Banner,Inner Mongolia)desert steppe area,the microhabitat inside and outside the C.korshinskii shrubs was selected as the research sample,the R.soongorica litter was used as the research object,and the use of mesh The litter decomposition bag method was used to investigate the distribution characteristics of arthropod communities in microhabitats inside and outside the shrubs,and to determine the mass loss and nutrient release dynamics of R.soongorica litter in the shrub microhabitats.The action law of mass loss and nutrient release dynamics revealed the action mechanism of litter arthropod in shrub microhabitats on the decomposition of R.soongorica litter under different water and heat conditions.The main results are as follows:(1)During the decomposition process of R.soongorica litter,only when the litter was decomposed in December.The abundance and group richness of litter arthropods were found to be significantly higher in the open spaces than beneath shrub canopy in semi-arid region,but the group richness of litter arthropods was found to be significantly lower in the open spaces than beneath shrub canopy only in arid region(P>0.05).There were no significant differences in Shannon-Wiener index and Margalef index between the two shrub microhabitats at either of the study sites(P>0.05).In addition to soil total carbon,which is a common factor affecting the distribution of litter arthropods.in the study area,it is also mainly affected by soil conductivity,pH value,clay silt and total nitrogen in semi-arid region,while in arid region,it is also mainly affected by soil water content and soil C/N.(2)The litter decomposition constant k in the study area showed that there was no significant difference between the microhabitats inside and outside the shrub,and was not related to the presence or absence of litter arthropod involved in the decomposition.When the litter was decomposed for 12 months,only in semi-arid region,the residual rate of litter was affected by litter arthropod and shrub microhabitats.At decomposition stage of 12 months,the mass remaining rate of litter was significantly higher in open spaces than beneath shrub canopy only in semi-arid region without the participation of arthropods;however,there was no significant difference between both shrub microhabitats with arthropod presence(P>0.05).But the residual rate of litter was less affected by litter arthropod and shrub microhabitats in arid region.At decomposition stage of 44 months,the mass remaining rate of litter was significantly higher in open spaces than beneath shrub canopy only in the arid region without the participation of arthropods;however,there was no significant difference between both shrub microhabitats with arthropod presence(P>0.05).But the residual rate of litter was less affected by litter arthropod and shrub microhabitats in semi-arid region.Compared with no litter arthropod involved in decomposition,when litter arthropod participated in decomposition,the decomposition half-life and turnover period of R.soongorica litter decreased from 1.28 times to 1.03 times in the relatively open spaces and shrubs microhabitats in semi-arid region,while in arid region increased from 0.93 times to 1.07 times With the extension of decomposition time,the contribution rate of litter arthropod to the mass loss of litter in the two study areas showed a single peak phenomenon,and reached a peak at 24 months after decomposition.(3)With the prolongation of decomposition time,in the shrub microhabitats of the arid and semiarid regions,the C elements of litter are in a released state as a whole,and are less affected by litter arthropod;while the P and N element of litter is less affected.The whole shows a fluctuating state of release-enrichment-release,and is also less affected by litter arthropods,litter arthropods have a positive effect on the release of K element in the litter as a whole,and the whole fluctuates from releaseenrichment-release.Changed to the state of full release;The C/N and lignin/N of litter first increased and then decreased with the prolongation of decomposition time.The contribution rate of litter arthropod to the nutrient release and nutrient ratio of R soongorica litter in arid and semi-arid regions was mainly affected by the lignin and cellulose contents in the litter.The comprehensive study shows that only in the initial stage of the decomposition of R.soongorica litter,With increased aridity,there was a transition from an ’overflow’ effect towards a ’facilitative’effect of shrubs on the distribution of litter arthropod abundance.The participation of litter arthropods shortened the decomposition time of litter in microhabitats inside and outside the shrubs in arid and semi-arid regions and promoted its decomposition.The arthropod as a whole had little effect on the release of C,N,and P elements from litter inside and outside the shrubs in arid and semi-arid regions,but had a positive effect on the release of K element and had a positive effect on the litter C/N and lignin/N have a negative effect,but this effect is related to the decomposition time.