Brueck, H.

Gao, Y. Z.

Giese, M.

Han, X. G.

Lin, S.

Taube, Friedhelm

Zhou, Z. Y.

English

University of Kentucky

University of Kentucky UKnowledge International Grassland Congress Proceedings 21st International Grassland Congress / 8th International Rangeland Congress Grazing and Drought Interactively Influence Total Plant Density Y. Z. Gao Christian-Albrechts University of Kiel, Germany M. Giese Christian-Albrechts University of Kiel, Germany Z. Y. Zhou Chinese Academy of Sciences, China X. G. Han Chinese Academy of Sciences, China Friedhelm Taube Christian-Albrechts University of Kiel, Germany See next page for additional authors 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/21/3-2/13 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. Presenter Information Y. Z. Gao, M. Giese, Z. Y. Zhou, X. G. Han, Friedhelm Taube, H. Brueck, and S. Lin This event is available at UKnowledge: https://uknowledge.uky.edu/igc/21/3-2/13 瞯 ]496　 瞯 　 Multifunctional Grasslands in a Changing World 　 Volume Ⅰ 　Grasslands/Rangelands Resources and Ecology ——— Soil‐Plant‐Animal InterrelationshipsGrazing and drought interactively influence total plant densityY . Z . Gao1 ,2 ,3 , M . Giese1 ,2 , Z . Y . Zhou4 , X . G . H an4 , F . Taube1 , H . Brueck 1 , S . L in21 Institute o f Plant Nutrition and Soil Science , Christian‐A lbrechts University o f K iel , D‐24118 , K iel , Germany , E‐mail :gaoyz108＠ nenu .edu .cn ; 2 Dep artment o f Plant Nutrition , China A gricultural University , Y uanmingyuan West Road 2 ,100094 Bei j ing , China ; 3 K ey L aboratory o f Vegetation Ecology , Northeast Normal University , Changchun , 130024China ;4 L aboratory o f Quantitative Vegetation Ecology , Institute o f Botany , Chinese A cademy o f Sciences , 100093Key words : heavy grazing , Inner Mongolian steppe , net primary productivity , plant heightIntroduction Great changes have taken place in vegetation in Inner Mongolian steppe due mainly to overgrazing in the past fourdecades . Overgrazing and N losses in combination with altered soil physical parameters and water availability further have beenshown to exert strong impact on plant productivity , total density and height ( Cingolani et al . , ２００５ ) . In addition to grazingdisturbance , drought also can significantly affect species height and density due to dif erent drought resistant or tolerant ability .However , drought and grazing always interactively influence the ecosystem processes in grazing ecosystems .Material and methods Our experiment was conducted at one site protected from grazing since １９７９ ( UG７９) , at one moderatelygrazed ( MG) and one heavily grazed ( HG ) site in Inner Mongolian steppe . At peak biomass time in ２００４ , ２００５ and ２００６ ,plant material of １ m x １ m ground area was cut with grass shears down to the soil surface at these three experimental sites . １０replications were done in each site . Additionally to the number of species , height , number of tillers and number of individualswere recorded before harvesting .Results There was no significant interaction of plant height between grazing and year ( P ＜ ０ .００１ ) ( Table １ ) . Plant heightdecreases with increasing grazing intensity . Plant height has no significant dif erence in two dry years ２００５ and ２００６ . Grazingand year interactively affect total plant density ( P ＜ ０ .００１ ) ( Figure １ ) . In all three years , total plant density was highest atsite HG and lowest at site UG７９ and was higher in ２００４ than in ２００５ and ２００６ .　 　 Figure 1 Total p lant density at three di ff erently managed sites . Symbols are as Table 1 .Table 1 The average height o f community (cm) at di f f erently managed sites . Signi f icant di f f erences between graz ing andyears are indicated by di f f erent small and cap ital letters , respectively .Sites ２００４ *２００５ 媼２００６ lAverageUG ３１ N.０ ２５ /.０ ２２  .７ ２６ 挝.２ aWG ２９ N.３ ２０ /.６ ２３  .１ ２４ 挝.３ aHG １１ N.０ ７  .０ ６ �.８ ９ 吵.０ bAverage ２３  .８ A １７ .５ B １７ 邋.６ BConclusions Heavy grazing leads to lower plant height and more small individuals . Drought reduces total plant density more atsite HG than site UG７９ , suggesting heavy grazing with a prolong drought can seriously deteriorate grassland .ReferenceCingolani , A .M . ,Noy‐Meir I .&Díaz S .(２００５) . Grazing effects on rangeland diversity : a synthesis of contemporary models .Ecological A p p lications １５ , ７５７‐７７３ .700 aA c::::::::J U G 7 9 600 ~ W G c ~ HG ·:;; 500 ::: <l) "O 400 = "' p., 300 3 0 200 c--100 2004 Year 

Grazing and Drought Interactively Influence Total Plant Density

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Grazing and Drought Interactively Influence Total Plant Density

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