模拟干旱增温对高寒草原土壤理化性质及酶活的影响OACHSSCD

Climate change is believed to exert pressure on the soil environment through direct and indirect ways,and ultimately on soil microorganisms.This study simulated drought and warming conditions by applying different gradient water control treatments(20%,30%,40%,60%,100%)and heating treatments(30-60 cm,60-90 cm,and 90-120 cm).It analyzed the effects on soil environment and microorganisms,following the changes in soil physical-chemical properties and enzyme activity.Results showed that:(1)The water control treatment reduced the value of soil pH,the content of soil organic carbon(SOC),dissolved organic carbon(DOC),total nitrogen(STN),ammonium nitrogen(AN),nitrate nitrogen(NN),total phosphorus(STP),and available phosphorus(SAP).The index of soil pH,AN,NN and SAP showed significant differences(P＜0.05)under the same soil layer with different treatments.All of aforementioned indexes showed significant differences(P＜0.05)in heating treatments under different soil layers,especially in the 0-30cm layer compared with the other three layers(30-60 cm,60-90 cm,and 90-120 cm).However,only DOC showed significant differences(P＜0.05)under different heating treatments in the same soil layer.(2)Compared to CK,most of the microbial entropy declined under the treatment of water controlling.Increasing water control gradient,except for S-UE urease(SUE),the activity of the other five microorganism's enzymes(alpha glucosidase(AG),beta-glucosidase(BG),leucine aminopeptidase(LAP),glucosaminidase(NAG),and S-alkaline phosphatase(ALP))decreased firstly,and then increased.After heating the 60-90 cm layer,the microbial entropy value of the 0-30 cm layer was larger than that of CK and was the largest.Generally speaking,except for a few groups,warming reduces the enzymatic activities of AG and BG,while in the 30-60 cm soil layer,heating increases the enzymatic activity of NAG,but in other soil layers,heating reduces the enzymatic activity of NAG.Heating increased the enzymatic activity of LAP in 0-30 cm and 60-90 cm layers,but reduced that in 30-60 cm and 90-120 cm layers.Warming only reduced the enzymatic activity of SUE in 60-90 cm layer,while promoted that in other soil layers.As for ALP,the activity was inhibited in 90-120 cm layer with warming treatment and promoted in other layers.(3)The water control treatment had deteriorated the soil quality index(SQI).The SQI of the group with 40%water control reduction decreased the least,while that of the group with 100%water control reduction decreased the most.For all warming treatment,the soil quality of the upper layer adjacent to the heating layer was the highest.This study also employed redundancy analysis to explore the effects of soil temperature and moisture changes on soil physical and chemical properties as well as on microorganisms,and the responses of microorganisms to soil environmental changes.These efforts laid the foundation for further in-depth research on the response mechanisms of soil to climate change.