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Effects Of Warming And Nitrogen Deposition On Soil Amino Sugar And Lignin Of Cunninghamia Lanceolata In Mid-subtropical

Posted on:2020-02-02Degree:MasterType:Thesis
Country:ChinaCandidate:Y LiFull Text:PDF
GTID:2370330620957032Subject:Ecology
Abstract/Summary:PDF Full Text Request
There is still no ideal technology which can effectively separate soil organic carbon fractions up to now,hence,the carbon fractions in soil organic matter is insufficiently understood,and the role both plants and microorganisms play in soil organic carbon accumulation is also unclear.Global warming and nitrogen deposition are two important aspects of global climate change.The change eventually affects soil organic carbon accumulation by impacting soil water,gas,heat,nutrient cycling and some others which contribute to the activities of plants and microorganisms.The current research on this change is mainly concentrated in temperate regions,so the effects of warming and its interaction with nitrogen deposition on plant-derived organic carbon and microbial-derived organic carbon in subtropical forests have not been reported yet.To this end,the experiment was conducted in Forest Ecosystem and Global Change Research Station in Chenda,Sanming in the Fujian Province of China.The experiments were established in 20 mini-plots(2 m×2 m)with the following treatments: control(CT),warming(W),nitrogen addition(N)and warming + nitrogen addition(WN).We sampled the soil of 0-10 cm and 10-20 cm in April 2018,respectively.The soil physical and chemical properties,microbial community structure,enzyme activities,amino sugars and lignin of these samples were determined.The aim of this study was to investigate the response of microbial community and enzyme activities,amino sugars and lignin to soil warming and nitrogen deposition in mid-subtropical Chinese fir plantations,and to understand the role of soil microbial community and enzyme activity played in the accumulation of amino sugars and lignin under global climate change.The main results are as follows:(1)Warming significantly increased the content of soil ammonia nitrogen and inorganic nitrogen in 0-10 cm and 10-20 cm soil layers,and the nitrogen application significantly increased the content of ammonia nitrogen and inorganic nitrogen in soil of10-20 cm soil layer,warming + nitrogen application treatment increased the content of soil nitrate in 0-10 cm layer and decreased the content of ammonia nitrogen and inorganic nitrogen in soil 10-20 cm,indicating that warming promoted soil organic nitrogen mineralization,and nitrogen application may inhibit the promotion of organicnitrogen mineralization by warming.Warming significantly decreased MBP in 0-10 cm soil layer,nitrogen application and warming + nitrogen application treatment decreased MBC and increased MBN in 0-10 cm soil layer,indicating that warming and nitrogen application inhibit soil microbial activity.(2)Warming significantly decreased the F:B ratio in 0-10 cm soil layer,decreased the content of fungi,bacteria,total PLFAs and F:B ratio in 10-20 cm soil layer,.Warming +nitrogen application treatment increased the content of bacteria and total PLFAs and decreased the F:B ratio in the 0-10 cm soil layer,and decreased the content of fungi,bacteria and total PLFAs in 10-20 cm soil layer.Theses change indicate that soil microbes adapt to environmental changes by reducing their biomass and adjusting their structure under increasing temperature conditions.(3)Warming significantly increased the NAG activity in 0-10 cm,10-20 cm soil layer.Warming decreased the AP activity and increased the ?G activity in 0-10 cm soil,decreased the ?G activity in 10-20 cm soil layer;nitrogen application treatment increased soil ?G,CBH,NAG and AP activities in 0-10 cm soil layer,and reduced AP activity in 10-20 cm soil layer;warming + nitrogen application treatment significantly reduced AP activity and increased ?G,CBH,NAG activity in 0-10 cm soil,reduced soil AP and ?G activity and increased CBH activity in 10-20 cm soil layer,indicates that the warming may change the carbon,nitrogen and phosphorus nutrient demand patterns of soil microorganisms.(4)Warming significantly increased the content of MurA in 10-20 cm soil layer and decreased the GluN/MurA ratio.The nitrogen application treatment increased the content of MurA and decreased the GluN/MurA ratio in 0-10 cm soil layer,and decreased the content of total amino sugar and GalN in 10-20 cm soil layer.Warming +nitrogen application treatment decreased the content of total amino sugar,GluN,GalN and GluN/MurA ratio in 0-10 cm soil layer,and decreased the content of total amino sugar,GluN,GalN and MurA in 10-20 cm soil layer,indicates that warming and nitrogen application are beneficial to the accumulation of bacterial-derived amino sugars in the soil,which is not conducive to the accumulation of fungal-derived amino sugars in the soil.(5)Warming decreased the content of vanillin(V),syringyl(S)lignin monomer and total lignin in 0-10 cm soil layer,and nitrogen application decreased the content of vanillin(V)lignin monomer in 0-10 cm soil layer,warming + application nitrogen significantly reduced the content of vanillin(V),syringyl(S)lignin monomer and total lignin in 0-10 cm soil layer,indicating that warming and nitrogen application promoted the decomposition of lignin.While warming,nitrogen application and warming +nitrogen application treatment significantly improved the ratio of(Ad/Al)v in the 0-10 cm soil layer,indicating that the combination of warming,nitrogen application and warming+ nitrogen application can increase the degree of oxidative decomposition of lignin in the surface soil.
Keywords/Search Tags:warming and nitrogen deposition, microbial community structure, enzyme activity, amino sugar, soil lignin
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