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Université de Mongolie-Intérieure (2013)

Photosynthetic Characteristics and Soil Respiration Under Warming and Precipitation Enhancement in Stipa Krylovii Steppe in Inner Mongolia

张立欣;

Titre : Photosynthetic Characteristics and Soil Respiration Under Warming and Precipitation Enhancement in Stipa Krylovii Steppe in Inner Mongolia

Auteur : 张立欣;

Grade : Master’s Theses 2013

Université : Université de Mongolie-Intérieure

Résumé partiel
Recently, global climate change has a great impact on terrestrial ecosystems. Grassland ecosystem is an important part of terrestrial ecosystem and very sensitive to climate change. Stipa bylovii is one of the main constructive species of typical steppe, S.krylovii steppe is an important class of grassland resources in Inner Mongolia, which plays an important role in livestock production. Research indicates that there is a trend of temperature increase and precipitation change is uncertain. It must have a profound impact on vegetation and soil of Inner Mongolia S.krylovii steppe in the future climate change. In this paper, we used open top chambers (OTCs) to simulate warming(+2℃, based on the local temperature increase from1961to2010and IPCC(2007)) and precipitation enhancement (+20%, based on the local average monthly precipitation during1961-2010) in the2011(July-September) and the whole growing season of2012(may-September). In order to examine the interactive effects of climate warming and precipitation enhancement on photosynthesis of S.krylovii and soil respiration of the Inner Mongolia S.krylovii steppe. To determine the impact of climate change. We measured soil temperature, soil moisture, air temperature, photosynthesis and each photosynthetic parameters of S.krylovii, soil respiration. to analyze the response and adaptation strategies of S.krylovii steppe under warming and precipitation enhancement. The main conclusions as follow :(1) In the growing season, Average air temperature of ground surface was increased1.91℃in daytime and3.14℃in diurnal under warming in Open top chambers (OTCs), but had no significant effect in nighttime air temperature and soil temperature. Warming treatment significantly reduced the soil moisture, in which significantly reduced10and30cm soil moisture. Warming precipitation enhancement treatment increased Average air temperature1.64℃.Precipitation enhancement treatment effectively alleviate the warming effect of OTCs, Warming precipitation enhancement treatment significantly reduced the10cm and20cm soil temperature, although soil moisture was reduced but no significantly effects. We found increase20%precipitation can not compensate soil water deficit conditions under warming.(2) Warming(1.91℃) made the photosynthetic rate(Pn) reduced22.0%of S.krylovii, but increased the water use efficiency(WUE)15.0%. Precipitation enhancement(20%) promote Pn14.0%. But had no significantly effects on WUE of S.krylovii. There was no significantly interactive effects were observed under warming precipitation enhancement treatment(1.64℃+20%) on Pn and WUE.(3) The change of photosynthetic rate and water use efficiency under warming and precipitation enhancement was caused by stomatal and non-stomatal factors. Warming treatments not only reduced soil moisture and photosynthetic parameters, but also made stomatal conductance(gs) of S.krylovii reduce28.0%, warming precipitation enhancement treatments could alleviate the conditions of soil water deficit, made gs reduce7.1%, while other photosynthetic parameters were also reduced, but no significant effects were found compared with the control. Precipitation enhancement treatments could promote each photosynthetic parameters, made gs increased5.48%. gs regulation the S.krylovii transpiration rate and photosynthetic rate under warming. In addition, precipitation enhancement partially alleviated the negative effect on each photosynthetic parameters of warming.(4) The warming treatment significantly inhibited soil respiration, made it reduced19%. But precipitation enhancement and warming+precipitation enhancement treatment significantly increased soil respiration. Made soil respiration increase18.6%and13%, respectively.

Mots clés : Global change; Photosynthesis; Stipa krylovii; Soil respiration; Typicalsteppe; Warming and precipitation enhancement;

Présentation (CNKI)

Page publiée le 15 mai 2018