Responses Of Dominant Plant Nutrient Reabsorption And Litter Degradation To Nitrogen And Phosphorus Supplementation And AMF Inhibition In Desert Steppe

Nutrient resorption is a vital nutrient conservation strategy for plants.Plant litter decay plays an important role in nutrient cycling in grassland ecosystem.However,there are few studies focus on the potential relationship between plant nutrient resorption and litter decay.In this paper,we tested the effects of arbuscular mycorrhizal fungi and nitrogen(N)and phosphorus(P)supplies on the nutrient resorption of common plant species in desert steppe in Ningxia.We analyzed the litter decay and carbon(C)mineralization process for experiment induced-plant litter via a laboratory culture experiment.Furthermore,we tested the the litter decay and carbon mineralization process under various soil nutrient levels.Main results as follow:(1)Field study found that:benomyl addition significantly enhanced the nitrogen resorption efficiency(NRE)of Astragalus melilotoides,Agropyron mongolicum and Stipa breviflora.Benomyl addition significantly increased phosphorus resorption efficiency(PRE)of A.melilotoides.Nitrogen supply significantly decreased PRE in A.mongolicum.P supply significantly reduced NRE in S.breviflora.Benomyl,N and P addition interactively altered the NRE in S.breviflora.(2)Laboratory culture experiment found that N and P and AMF significantly changed the litter quality for A.melilotoides,A.mongolicum and S.breviflora.A.mongolicum and S.breviflora litter under P and N+P treatments significantly enhanced early CO2 mineralization rate when compared to other treatments.A.melilotoides litter under P addition treatment decreased 24 h C mineralization,CO2 accumulated mineralization,and priming effect when compared to other treatments.Compared with N and benomyl supply,P.mongolicum and S.breviflora litter under P treatment increased CO2 accumulated mineralization.Benomyl addition reduced the litter loss ratios for A.melilotoides and A.mongolicum.(3)Laboratory culture experiment found that N and P additions interactively shaped different plant litter decay and C mineralization.P supply enhanced the litter loss ratios of P.mongolicum,Salsola collina and Artemisia scoparia.P input significantly reduced the 24 hour C mineralization in A.melilotoides,A.mongolicum,S.collina,and A.scoparia litter added tubes.Compared with N supply,P input significantly increased CO2 accumulated mineralization and and priming effect under plant litter added tubes.Summary,AMF can shape the nutrient resorption and litter decay for dominant plants in desert steppe.The impacts of AMF on plant nutrient resorption and litter degradation was regulated by soil available N and P levels.Soil fertility and plant litter quality are vital factors changing litter decay and soil C mineralization.