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sur le développement des zones arides et semi-arides

Titre : The Effect of Warming and Precipitation on Process of Carbon Budget in Stipa Breviflora Desert Steppe

Auteur : 郭娜

Grade : Doctoral Dissertation 2022

Université : Inner Mongolia Agricultural University

Résumé partiel
The Stipa breviflora desert grassland is an important part of the ecological carbon（C）pool,and its carbon budget process is not only an important part of affecting the global climate,but also an important part of responding to global climate change.Studying the impact of different climate change scenarios on the key processes of desert grassland carbon budget and the regulation mechanism can improve people’s understanding of the process of ecosystem carbon balance under the background of climate change.At the same time,it has important scientific significance for understanding the soil carbon cycle process of fragile habitats.Thus,an experiment was conducted to investigate the photosynthetic capacity of dominant plants in the Stipa breviflora desert steppe,the characteristics of the stable carbon isotope of leaf-litter-root-soil continuum,soil respiration and oxidation and reduction of soil methane under three levels of warming（T0:ambient temperature ;T1:T0+2℃ ;T2:T0+4℃）,three levels of increased precipitation（W0:ambient precipitation ;W1:W0+25% ;W2:W0+50%）treatments and their interaction（T*W）in Inner Mongolia,China.Temperature enhancement was achieved by open-top growth chamber（OTC）,and precipitation enhancement was achieved by self-made rain interception device.The results as follows :（1）Physiological parameters of plant photosynthesisWarming（T）,increased precipitation（W）and their interactions treatment significantly improved the gas exchange parameters of the leaves of Stipa breviflora,Cleistogenes songorica and Kochia prostrata.The C3 plants was significantly restricted by stomatal factors,while the C4 plants was not restricted by it.The instantaneous water use efficiency（WUE）and intrinsic WUE of the five plants have a very significant negative correlation with intercellular carbon dioxide（CO2）concentration（Ci）.The parameters fitting the photosynthetic/CO2 response curve showed that Stipa breviflora had a wider growth range of photosynthetically active radiation（PAR）,was more adaptable to low PAR,had the ability to preferentially accumulate photosynthetic products and higher assimilation adaptability.

Mots clés : Stable Carbon Isotope ;Photosynthesis;Fluorescence ;Soil Respiration ;Flux;

Présentation (CNKI)