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Effects Of Different Warming Modes On Soil Organic Carbon And Microorganisms In A Subtropical Chinese Fir Plantation

Posted on:2022-01-14Degree:MasterType:Thesis
Country:ChinaCandidate:P F ZhangFull Text:PDF
GTID:2480306752970019Subject:Physical geography
Abstract/Summary:PDF Full Text Request
Under the background of global climate change,it is a hot topic to study the storage change and stability of soil carbon pool.Temperature is an environmental factor that has a great influence on the process of soil carbon cycle,and it is also a significant feature of future climate change.It is found that the response of soil carbon pool to warming has great uncertainty,which is largely due to the inconsistent response of soil microorganisms to temperature.For example,the increase of soil carbon input caused by the increase of temperature can also improve soil / heterotrophic respiration.The loss of soil carbon pool caused by the increase of respiration intensity can partly offset the increase of soil carbon input caused by the increase of temperature.Therefore,the change of soil organic carbon pool and the feedback response of soil microorganisms after climate warming have become the focus of current research.At present,a large number of field warming simulation experiments have been carried out on the impact of climate warming on soil carbon pool.However,different warming methods may lead to great differences in the experimental results.Therefore,the comparative study on the effects of different warming methods(cable warming + 4 ?,open top box warming + 4 ? and open top box cable joint warming +4 ?)on soil carbon pool has important reference value for eliminating the uncertainty of related research.In order to provide basic data and scientific support for further understanding of soil carbon dynamics and microbial response mechanism of subtropical forest ecosystem under the background of global warming,three different field warming control experiments were set up in humid subtropical forest area,focusing on the effects of warming on soil organic carbon and microorganisms of young Chinese fir forest.The results showed that soil respiration increased by 8.99%-31.9% and heterotrophic respiration increased by 10.99%-38.09%.The results showed that the average annual rate of soil respiration increased by 20.63%,8.99% and 31.9%,and the average annual rate of heterotrophic respiration increased by 21.13%,10.99% and 38.09%,respectively.Correlation analysis showed that soil temperature could explain 72%-77% of the seasonal variation of soil respiration and 64%-73% of the seasonal variation of heterotrophic respiration,while the correlation between soil moisture and soil respiration and heterotrophic respiration was not significant(P > 0.05).The Q10 values of soil respiration and heterotrophic respiration were decreased by warming treatment: the Q10 values of soil respiration and heterotrophic respiration in the control treatment were 1.35 and 1.65,respectively;after cable warming treatment,open top box warming treatment and open top box cable combined warming treatment,the Q10 values of soil respiration were 1.22,1.22 and 1.11,respectively;the Q10 values of heterotrophic respiration changed to 1.49,1.49 and 1.35.The results showed that the three warming treatments could reduce the acid proof biomass of five kinds of microbial phospholipids,including Gram-positive bacteria,Gram-negative bacteria,actinomycetes,arbuscular mycorrhizal fungi and fungi.The three warming treatments increased the relative abundance of Gram-positive bacteria in each soil layer,but decreased the relative abundance of Gram-negative bacteria,actinomycetes,arbuscular mycorrhizal fungi and fungi Abundance.RDA analysis of soil microbial community structure showed that the control plots and the plots with different warming treatments were obviously separated in each soil layer,which indicated that the soil microbial community structure of each soil layer was significantly changed by different warming treatments.In0-10 cm soil layer,the contents of total organic carbon and soluble organic carbon were significantly positively correlated with microbial community structure.In 10-20 cm soil layer,the contents of soluble organic carbon and soluble organic nitrogen were significantly positively correlated with microbial community structure.In 20-40 cm soil layer,the contents of soil moisture and soluble organic carbon were significantly positively correlated with microbial community structure.The activities of glucosidase and cellulose hydrolase in different soil layers were inhibited to a certain extent by cable warming,open top box warming and combined warming treatment,and only combined warming treatment made the inhibition reach a significant level(P < 0.05);the activities of peroxidase,leucine aminopeptidase and acid phosphatase in different soil layers were significantly increased by soil warming,atmospheric warming and combined warming treatment The activities of phenoloxidase and acetylglucosidase in different soil layers were significantly decreased(P < 0.05).Redundancy analysis of environmental factors affecting soil enzyme activities showed that nitrate nitrogen was the common factor driving the changes of soil enzyme activities in all soil layers.There was a significant positive correlation between p H and soil enzyme activity in 0-10 cm soil layer,total organic carbon content in 10-20 cm soil layer and ammonium nitrogen content in 20-40 cm soil layer.The warming treatment reduced soil particulate organic carbon by 10.31%-35.4% and soil mineral bound organic carbon by 6.42%-16.01%,indicating that soil particulate organic carbon content is more sensitive to warming.In this study,different warming treatments had no significant effect on the content of stable bound organic carbon and calcium bound organic carbon,but significantly reduced the content of iron aluminum bound organic carbon in soil,which indicated that the decrease of mineral bound organic carbon content by warming treatment was mainly caused by the decrease of iron aluminum bound organic carbon content.
Keywords/Search Tags:warming mode, soil respiration/heterotrophic respiration, soil organic carbon component, microbial community structure, soil enzyme activity
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