Effects Of AM Fungi On Litter Decomposition And Soil Nutrient Content Under Different Competitive Treatments

Arbuscular mycorrhizal fungi(AMF)are symbiotic organisms formed by plants and AMF fungi.This symbiotic organism supplies root exophytic mycelia through carbohydrates produced by plant photosynthesis and exchanges and absorbs soil nutrients to promote plant growth,thus affecting the plant-soil ecological process.Litter,as a common nutrient carrier in nature,is the source of soil nutrients and the guarantee of soil fertility.Studies have reported that AM saprophytic litter nutrients and decomposes nutrients from Karst litter for plant growth.However,these studies are limited to single plant inoculation experiments.Species in natural communities always coexist with other species in the same habitat,and regulate the limited nutrient resources by competition.How AM fungi regulate nutrient release from soil litter and change soil properties under competitive conditions is a theoretical issue deserving attention.Therefore,Broussonetia papyrifera and Carpinus pubescens were selected for competitive treatment in karst natural community habitat,inoculated with AM fungi Glomus etunicatum and mixtured the litter of Broussonetia papyrifera and Itea yunnanensis treated.A three-factor experiment was designed.(B.papyrifera intra-species competition,B.papyrifera + C.arpinuspubes inter-species competition,C.arpinuspubes intra-species competition),To explore the effects of AM fungi on litter decomposition and soil nutrients under species competition.The litter decomposition property index and soil nutrient index were determined by experiments.The main results are as follows:(1)Without litter treatment,the spore density,mycelium density and pH were significantly increased by AMF inoculation.Under litter treatment,AMF inoculation significantly increased the spore density,mycelium density and pH under intraspecific competition of B.papyrifera and interspecific competition,increased the spore density and mycelium density under intraspecific competition of C.pubescens as well.Without AMF inoculation treatment,the application of litter significantly reduced the pH of the soil under intraspecific competition of B.papyrifera and interspecific competition,the pH of soil under interspecific competition was significantly increased under intraspecific competition of C.pubescens as well.Under AMF inoculation treatment,the soil pH and spore density under the intraspecific competition of C.pubescens were significantly increased by adding litter.(2)Inoculation of AMF significantly reduced the concentration of nitrogen and potassium in the residual litter under intraspecific competition of B.papyrifera,increased the concentration of phosphorus in the residual litter,and significantly reduced the concentration of the residual litter under interspecific competition as well.The content of nitrogen,potassium and phosphorus in the residual litter under intraspecific competition of B.papyrifera were significantly decreased by AMF inoculation.The contents of litter nitrogen and phosphorus and potassium were significantly increased by AMF inoculation under the intraspecific competition of B.papyrifera.(3)Without litter treatment,the content of total phosphorus,total potassium and available potassium in the soil were significantly reduced by AMF under intraspecific competition of B.papyrifera and interspecific competition,the content of total potassium in soil under intraspecific competition of C.pubescens was significantly decreased as well.Under litter treatment,the content of total nitrogen,total phosphorus and total potassium in soil was significantly decreased by AM fungi under intraspecific competition of B.papyrifera,soil total nitrogen and organic matter were significantly increased under interspecific competition and total phosphorus and potassium in the soil were decreased and the organic matter was increased under intraspecific competition of C.pubescens as well.Without AMF inoculation treatment,the application of litter significantly reduced soil total phosphorus and total potassium under interspecific competition,reduced the total phosphorus and available phosphorus under intraspecific competition of C.pubescens as well.Under AMF inoculation treatment,the application of litter significantly decreased the total potassium and available potassium in the soil under intraspecific competition of B.papyrifera,increased soil total nitrogen and organic matter?decreased total potassium and available potassium under interspecific competition and significantly reduced the total phosphorus and available phosphorus under intraspecific competition of C.pubescens as well.(4)Without litter treatment,AMF inoculation significantly increased soil urease activity and EE-GRSP under intraspecific competition of B.papyrifera,significantly increased soil urease activity,decreased alkaline phosphatase activity and EE-GRSP under interspecific competition and increased the urease activity under intraspecific competition of C.pubescens as well.Under litter treatment,AMF inoculation significantly reduced soil EE-GRSP under intraspecific competition of B.papyrifera and significantly improved soil alkaline phosphatase activity under interspecific competition.Without AMF inoculation treatment,the application of litter significantly increased soil urease activity and EE-GRSP under intraspecific competition of B.papyrifera,significantly increased soil urease activity and decreased alkaline phosphatase activity under interspecific competition as well.Under AMF inoculation treatment,the application of litter soil significantly reduced urease activity and increased EE-GRSP under intraspecific competition of B.papyrifera,increased the activity of alkaline phosphatase and EE-GRSP in soil under interspecific competition as well.Generally speaking,the effects of AM fungi on litter decomposition,soil nutrients and enzyme activities were different under different competition treatments.AM fungi significantly increased spore density,mycelium density and urease activity in all treatments and reduce pH.Facilitated decomposition of litter nitrogen and potassium and increasing EE-GRSP and Reduced soil total phosphorus and potassium under intraspecific competition of B.papyrifera Reduced Soil Total Potassium under Intraspecific Competition of C.pubescens.Reducied soil total phosphorus,potassium,alkaline phosphatase activity and EE-GRSP and reduce pH under interspecific competition.Litter significantly increased urease activity,EE-GRSP content and decreased pH under intraspecific competition of B.papyrifera,increased pH under intraspecific competition,of C.pubescens.increased urease activity under interspecific competition,and decreased pH,total phosphorus,total potassium and alkaline phosphatase activity.Compared with AM fungi,AM fungi × litter significantly increased EE-GRSP content and decreased soil potassium under intraspecific competition of B.papyrifera.increased spore density,organic matter,alkaline phosphatase activity and EE-GRSP under interspecific competition and reduced soil potassium.Compared with litter,the pH,spore density,mycelium density and total nitrogen under intraspecific competition of B.papyrifera were significantly increased.,increased spore density,mycelium density,organic matter and reducing total phosphorus and potassium under intraspecific competition of C.pubescens,increased the spore density,mycelium density,total nitrogen,organic matter and alkaline phosphatase activity and pH under interspecific competition.