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Study On Forest Soil Temperature And Organic Carbon Mineralization Of Permafrost Region In The Great Hing'an Mountains

Posted on:2021-03-30Degree:MasterType:Thesis
Country:ChinaCandidate:X F DongFull Text:PDF
GTID:2370330611455729Subject:Physical geography
Abstract/Summary:PDF Full Text Request
Under the background of climate warming,the dynamics of soil carbon pools in permafrost regions is a hotspot of current research on ecological geography.Although a lot of studies have been carried out by predecessors,further research and discussion are needed on how soil temperature changes with depth in frozen soil regions and how soil carbon mineralization responds to environmental changes.Based on the ground temperature data of forest soil borehole monitoring in Daxing'anling permafrost region,this paper discussed the vertical structure and ecological benefits on soil organic carbon mineralization of the ground temperature in permafrost region.Therefore,we collected0-6 m soil samples to analyze the distribution of soil carbon and nitrogen with depth,and through the incubation experiments of different temperature and water gradient to reveal the response characteristics of forest soil organic carbon mineralization to temperature,water,forest type and depth in permafrost region,and clarified the temperature sensitivity of each layer of soil organic carbon mineralization under each water treatment.The main conclusions are as follows:?1?The average soil temperature of each soil layer varied in waves with the month,and the phases of its maximum and minimum values lagged with the depth;The variation of ground temperature with depth accorded with composite index function y=y0+a?1-exp?bx??,and the functions of"matching"months?such as March and September,June and December?were basically symmetrical to each other;The annual difference of average soil temperature of each soil layer decreased with depth,and the annual range of average soil temperature in 20 cm soil was the largest,32.19C.The annual average temperature difference of 670 cm soil was the smallest,only 0.8C.?2?The mineralization rate of soil organic carbon decreased first and then stabilized with the incubation time,the accumulated carbon mineralization was0.39-2.29 mg g-1,and the value of Larix gmelini was higher than that of Pinus sylvestris var.Mongolica;Soil organic carbon mineralization significantly increased with temperature?p<0.001?,but its response to water content varied with forest type,and the interaction of temperature and moisture had no significant effect on soil organic carbon mineralization.Temperature sensitivity?Q10?of soil organic carbon mineralization wasthe lowest in the larch soil with a soil moisture content of 30%?2.11?,and the hHioghwee?s3vt?e ir,Tn th htehe eav vaseloruiaelg se c wuvleatrlueur een oo?tf2.spi5g0Hn?,i fTiwciOathCnt,l ayD laOafrfCce,ch t TesdNo,ib l yN wsOiot3i-hl-Nma,oaimsntodui srtNeu aHren4+d-c fNoo nritenes ntp tte yropfme as6f.r0o%st.layer were higher than those in the active layer.During the 60-day incubation period,the accumulated mineralization of soil organic carbon ranged from 0.20 to 4.86 mg C,which varied with depth,temperature and moisture.Q10 values gradually decreased in the active layer,and reached the minimum in the transition layer.It showed the trend of increasing first and then decreasing in the permafrost layer.
Keywords/Search Tags:climate change, permafrost region, ground temperature, soil moisture, organic carbon mineralization, temperature sensitivity
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