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Inner Mongolia University (2021)

Effects of Different Grazing Types on Functional Traits of Dominant Species in Typical Steppe of Inner Mongolia

王铮

Titre : Effects of Different Grazing Types on Functional Traits of Dominant Species in Typical Steppe of Inner Mongolia

Auteur : 王铮

Grade : Master 2021

Université : Inner Mongolia University

Résumé
Plant functional traits are the basis for the study of ecosystem function and ecological adaptability.Plants can change their own functional traits and timely adjust adaptation strategies to adapt to changes in the external environment.Therefore,plant functional traits can effectively reflect the response of plants to different grazing types.In the grassland grazing ecosystem,plant functional traits can effectively reflect the responses of plants to different grazing intensities and grazing types.However,there are relatively few studies on the effects of different grazing types on plant functional traits in the temperate typical steppe.In this study,three kinds of grazing types,namely single grazing of cattle,single grazing of sheep and mixed grazing of cattle and sheep,were set up on the typical grassland in Inner Mongolia.Stipa grandis,Leymus chinensis,Anemarrhena asphodeloides,Cleistogenes squarrosa,Agropyrom cristatum were selected of the five dominant species,sixteen plant functional traits were determined,such as specific leaf area,leaf dry matter content and leaf nitrogen content,etc.The differences of functional traits and their intra-specified variations of dominant species under different grazing types were analyzed,the relationship between functional traits and water use efficiency was revealed,and the adaptation strategies of plants exposed to external disturbance were discussed from the perspective of functional traits.The main results and conclusions are as follows:1)the responses of functional traits of dominant species to grazing were consistent in the typical steppe of Inner Mongolia.After grazing,the plant height became shorter,the root length became shorter,and the stem-leaf ratio and root-shoot ratio increased,indicating that the plants escaped grazing through morphological and biomass changes.In addition,regardless of the grazing types,the specific leaf area and nitrogen content of the dominant plants in the grassland all increased.These changes indicated that the plants could increase the grazing tolerance by increasing the regeneration rate.2)The functional traits of Stipa grandis were significantly affected by grazing cattle,the leaf thickness was significantly increased to 0.07cm in single grazing cattle.Root shoot ratio was significantly increased to 1.67 in single grazing cattle.The root carbon content and root nitrogen content were significantly increased,which were246.28mg/g and 9.34mg/g in single grazing cattle.Grazing sheep affected the growth of Leymus chinensis,and significantly increased the stem leaf ratio,which was 0.99in single grazing sheep.The specific leaf area was significantly increased,which was152.45cm2/g in single grazing sheep.The nitrogen content of stem and leaf was significantly increased to 19.07mg/g and 34.36mg/g in the mixed grazing of cattle and sheep,to 15.91mg/g and 31.94mg/g in the single grazing sheep.The leaf dry matter content was significantly decreased,which was 344.17mg/g in mixed grazing of cattle and sheep,and 358.08mg/g in single grazing sheep.The grazing sheep had a greater impact on the water use efficiency of Leymus chinensis,Anemarrhena asphodeloides and Agropyrom cristatum.3)Grazing increased the intraspecific variation of plants and tended to give priority to morphological changes ;The functional traits of Cleistogenes squarrosa were more stable after grazing.4)Stipa grandis and Cleistogenes squarrosa can improve drought resistance and fix carbon as much as possible,so it is considered that they can better adapt to grazing and have both drought resistance and carbon fixation ability.The results of this study showed that mixed grazing was more beneficial to the sustainable use of typical grassland in Inner Mongolia than single grazing under the premise of reasonable grazing pressure.

Mots clés : plant functional traits ;grazing types ;morphological traits ;intraspecific variation ;trait tradeoff ;Water use efficiency ;

Présentation (CNKI)

Page publiée le 18 novembre 2021