| Plant aboveground and belowground input is the main source of soil organic carbon,and it is also the main carbon source of soil microorganisms.Plants aboveground and belowground inputs differentiate in quantity,quality,and input time and frequency.Therefore,it may produce different soil microbial activity,abundance and community composition,and have different effects on the quantity and stability of soil carbon pool.However,few experiments can distinguish aboveground and belowground inputs in situ,and compare their effects on microbial activity,abundance,community composition,quantity and stability of carbon pool.For this reason,this study was conducted in the 2018 at the aboveground and belowground input positioning test station of grassland plants in Haicheng,Liaoning Province.At each block,there were four treatments:(1)no plant input(NI),(2)only plant belowground input(+B),(3)only plant aboveground input(+A),(4)both aboveground and belowground inputs(+A+B).In2019 year,the end of April(before the growing season)and the end of October(after the growing season)are non-growing seasons.0～20 cm soil of each community was collected,measure soil enzyme activity.,soil respiration rate,soil microbial abundance and community.Analyze aboveground and belowground inputs who plays a more important role in maintaining microbial activity,abundance and community.In addition,0～20 cm soil was collected in the autumn of 2018,2019,2020 and 2021.Measure the contents of soil organic carbon,total nitrogen,particulate organic carbon and mineral-associated organic carbon,and analyze the effects of plant aboveground and belowground input on the quantity and stability of soil organic carbon pool.The research results are as follows:(1)In the non growing season,the contribution of plant aboveground and belowground inputs to the maintenance of soil microbial community varies before and after the growing season.Before the growing season,the soil respiration rate,cumulative respiration and most microbial groups abundance(non-specific bacteria,Gram-positive bacteria,Gram-negative bacteria and Anaerobesa)show that +A+B>+A>+B≈NI,the microbial community structure of+A+B treatment is similar to +A treatment,but significantly different from NI and + B treatment,description compared to belowground input,plant belowground input are closer to both above and belowground input on soil microbial activity,abundance and community composition,it means that the plants aboveground input plays a major role in soil microbial activity,abundance and community composition before the growing season;On the contrary,after the growing season,the soil respiration rate and cumulative respiration showed +A+B>+B>+A≈NI,all soil microorganisms groups abundance show +A+B≥+B>+A>NI,+A+B treatment microbial community structure almost coincident with + B treatment,but significantly different with +A and NI treatments,description compared to aboveground input,plant belowground input are closer to both above and belowground input on soil microbial activity,abundance and community composition,it means that the plants belowground input plays a major role in soil microbial activity,abundance and community composition after the growing season.This shows that plants aboveground and belowground inputs have seasonal differences in maintaining soil microorganisms.(2)Short term experiment for 4 years did not change the amount of soil total organic carbon,but had a certain impact on the composition of soil active carbon(particulate organic carbon).There was no difference in soil organic carbon,total nitrogen content and mineralassociated organic carbon content among different input treatments,but the content of soil particulate organic carbon in +A+B and +B plots was higher than that in +A and NI plots(P <0.05).Therefore,the proportion of particulate organic carbon in total soil organic carbon in the former was higher than that in the latter,and the proportion of mineral-associated organic carbon in soil organic carbon was lower than that in the latter(P < 0.05).This shows that compared with aboveground input,belowground input of plants contributes more to soil particulate organic carbon,but will reduce the stability of soil carbon poolIn summary,soil microorganisms are sensitive to aboveground and underground inputs,while the response of soil organic carbon is a long-term process. |
