Dong, Xiaoyu

Fu, Hua

Guo, Ding

Li, Xiaodong

Li, Xudong

English

University of Kentucky

University of Kentucky UKnowledge International Grassland Congress Proceedings 21st International Grassland Congress / 8th International Rangeland Congress Effect of Soil Temperature and Soil Moisture on Soil Respiration of Ungrazed Grassland in Loess Plateau , Gansu Xudong Li Lanzhou University, China Ding Guo Lanzhou University, China Xiaodong Li Lanzhou University, China Xiaoyu Dong Lanzhou University, China Hua Fu Lanzhou University, China Follow this and additional works at: https://uknowledge.uky.edu/igc  Part of the Plant Sciences Commons, and the Soil Science Commons This document is available at https://uknowledge.uky.edu/igc/21/2-1/30 The 21st International Grassland Congress / 8th International Rangeland Congress took place in Hohhot, China from June 29 through July 5, 2008. Proceedings edited by Organizing Committee of 2008 IGC/IRC Conference Published by Guangdong People's Publishing House This Event is brought to you for free and open access by the Plant and Soil Sciences at UKnowledge. It has been accepted for inclusion in International Grassland Congress Proceedings by an authorized administrator of UKnowledge. For more information, please contact UKnowledge@lsv.uky.edu. 　 Multifunctional Grasslands in a Changing World 　 Volume Ⅰ 　 瞯 ]325　 瞯Grasslands/Rangelands Resources and Ecology ——— Soil Quality and Plant NutritionEffect of soil temperature and soil moisture on soil respiration of ungrazed grassland in LoessPlateau , GansuL i Xudong , Guo Ding , L i X iaodong , Dong X iaoyu , Fu Hua倡Key L aboratory o f G rassland A gro‐ecosystem ,M inistry o f A griculture , College o f Pastoral A gricultural Science andTechnology , L anz hou University , L anz hou 730000 , China . 倡 Corresponding author . E‐mail address :f uhua＠ lz u .edu .cnKey words : soil respiration , soil temperature , soil moisture , grassland , Loess PlateauIntroduction Soil respiration ( SR) is a major component of greenhouse gas emission and is a crucial pathway of the C cycle . Thepotential increase of SR caused by global warming may present a positive feedback effect on atmospheric CO２ and climate change( Kirschbaum ,１９９５) . However , the factors that control the exchange of CO２ between soil and atmosphere in Loess Plateau ,Gansu are not well understood . The results in this paper represent a preliminary exercise in studying SR variations and itscorrelation with soil temperature ( Ts) and soil moisture ( Ms) .Materials and methods Monthly measurements of SR were made from August ２００６ to July ２００７ in a fenced Stipa . bungeanagrassland ( free from grazing since Oct . ２００５) which located in the Semi‐Arid Climate and Environment Observatory Station ofLanzhou University ( ３５° ５７′ N , １０４° ０９′ E ) . The measurements of SR were made by using a LICOR ６４００ portablephotosynthesis system fitted with a soil respiration chamber ( LICOR , Inc . , Lincoln NE) . SR was measured between ８ :００ ～１０ :００ .１２ PVC collars that held the SR chamber were set ２４ hours before SR measuring . Ts at ２ , ５cm depths and Ms down to１０cm were measured simultaneously .Figure 1 Diurnal variations o f SR .Results Diurnal variations of SR could be expressed as one‐humped curves , reaching to the maximum around １３ :００and falling to the minimum between ０ : ００ ～ ３ : ００ indifferent growing periods . Ts at ５cm depth was thedominant factor controlling SR ( P ＜ ０ .００１ ) . Ms hadrelatively little effect on diurnal SR variation as it changedlittle within one day . Seasonal SR variation was dominatedby Ts‐Ms interaction and root biomass . The maximum ofSR was observed in Jun ,２００７ , while the minimum in Nov ,２００６ . Negative CO２ efflux was observed from Nov , ２００６to Jan , ２００７ . The correlation between Ts at ２cm ,５cmdepths and SR were much remarkable( R２ ＝ ０ .５４ and R２ ＝Figure 2 Seasonal variations o f SR , Ts and Ms .0 .５６ , P ＜ ０ .００１ ) . Ms was secondary factor controlling SRvariation at seasonal scale . The single Ms effect on SR wasexamined by normalizing SR at a reference value of ２０ ℃ ,and the correlation was significant ( R２ ＝ ０ .３９ , P ＜ ０ .００１ ) .When both Ts and Ms effects on SR were considered , SRcould be given better simulations :SR ＝ ０ .０２４T ＋ ０ .０３９Ms － ０ .２６ ( R２ ＝ ０ .７３ , P ＜ ０ .００１) .Conclusions Ts was dominant factor controlling diurnal SRvariation when Ms was relatively stable . Both Ts and Mseffects on SR could better reveal SR variation at seasonalscale , thus the predictive capacity of the model about SRvariation has been improved .ReferenceKirschbaum , M .U .F . , １９９５ . The temperature dependenceof soil organic matter decomposition , and the effect onglobal warming on soil organic C storage . Soil Biol .Biochem . ２７ , ７５３‐７６０ .~ 2.0 !/) ~ 1.6 E N 1.2 0 0 0.8 0 E 0.4 ::J s; 0.0 ~ 2.0 !/) ~ 1.5 E a 1.0 () 0.5 0 E 0 0 :J ffi -0.5 40 ::R 30 0 10 9:00 --o-12 Sept,2006 -+-29 Jun,2007 13:00 17:00 21 :00 3:00 Local time -SR --0- Ts 40 30 20 ~ {!:. 10 ~-ilWWU>.b_..,.,~cwwuw---~ o -10 o C=illll~~~~~~~~~~~~~ Aug Sept Oct Nov Dec Jan Feb Mar Apr May Jun Jul 

Effect of Soil Temperature and Soil Moisture on Soil Respiration of Ungrazed Grassland in Loess Plateau , Gansu

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Effect of Soil Temperature and Soil Moisture on Soil Respiration of Ungrazed Grassland in Loess Plateau , Gansu

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