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Inner Mongolia Agricultural University (2013)

Study on Biomass Dynamics and Carbon Storage Distribution in Desert Steppe

Yang Zuo Zuo

Titre : Study on Biomass Dynamics and Carbon Storage Distribution in Desert Steppe

Auteur : Yang Zuo Zuo

Grade : Doctoral Dissertation 2013

Université : Inner Mongolia Agricultural University

Résumé
Grassland ecosystem plays an important role in the global carbon cycle, so far therehave a great deal of basic information on grassland biomass and carbon accumulationwere accumulated. Many scholars have done a lot of research work on biomass dynamicand carbon stock in typical and meadow steppe. While for the studies about biomassdynamics and carbon stocks in desert steppe, there are only few articles, especiallybelow-ground biomass seasonal dynamics. Due to the lack of field survey data, thecarbon storage estimation of China grassland is uncertain. Therefore, in this paper, wetake Stipa klemenzii steppe as research object, which is the preventative grassland ofdesert steppe in Inner Mongolia. The above and below ground biomass, soil organiccarbon content have been surveyed and determined from May to September. Thedynamics of biomass and soil organic carbon in Stipa klemenzii steppe were analized.The spatial and temporal distribution of carbon stocks in Sonid Youqi were studied, theinfluence factors such as climate, grazing and soil microbial to desert steppe carbon poolswere explored, which can improve the ability to estimate carbon storage in terrestrialecosystems.1. The seasonal dynamics and its influence factors of biomass, root : shoot ratio andsoil organic carbon in Stipa klemenzii steppe was studied by2years determination.(1) The biomass of Stipa klemenzii steppe in different years shows differentdynamics due to precipitation distribution. The aboveground biomass in2011showedremarkably single-peak curve, the peak value appeared in late June. The belowgroundbiomass showed the principle of N type, the peak value appeared in late July. While, in2012, both the above and below ground biomass showed single-peak curve, the peakvalue appeared in July or August.(2) The distribution of belowground biomass showed T type in the pattern ofvertical space and progressively decreased from top soil to bottom soil. Below-groundbiomass in soil layer of0-30cm accounted for more than80%of the total belowgroundbiomass.(3) Seasonal fluctuations of the root : shoot ratio of Stipa klemenzii steppe iscomparatively large. It is significantly correlated with aboveground biomass, and is asignificant negative correlation with cumulative precipitation and last month temperatures, and is a significant positive correlation with the0-10cm soil moisture.(4) The seasonal variation of soil organic carbon showed a single-peak curve, it is asignificant positive correlation with below ground biomass in the soil layer of0-10cm.2. Based on3years field survey data and MODIS-NDVI data, the Above-groundbiomass of Sonid Youqi were estimated, combining root : shoot ratio and soil organiccarbon data, the total carbon storage of Sonid Youqi were estimated.(1) Total carbon storage of Sonid Youqi in2006,2011and2012is respectively329.86Tg,328.63Tg and335.03Tg. Soil carbon storage accounted for more than95%of the total carbon storage. Root carbon storage is20times of above ground biomass.(2) The average aboveground biomass of Sonid Youqi in2012was significantlyhigher than those in2006and2011, which is respectively59.08g/m 2,37.59g/m 2and41.23g/m 2. Soil carbon density in different grassland is different, the soil carbon densityin Stipa breviflora steppe is the highest, which is18690.3g/m 2,the soil carbon density insteppe desert is the lowest, which is4358.43g/m 23. The influence of climate, grazing and soil microbial to grassland biomass andcarbon pool in Sonid Youqi.(1) Nearly30years, temperature in Sonid Youqi is an increasing trend especially insummer and autumn, while the precipitation decreased. The above carbon pool and rootcarbon pool showed a significant positive correlation with annul precipitation, and anegative correlation with temperature. The climate change in Sonid Youqi is notconducive to the accumulation of carbon reserves.(2) With the increasing of grazing intensity, the above and below biomass of Stipaklemenzii steppe decreased during growing season. Compared with CK, soil organiccarbon in LG increased, while soil organic carbon in MG, HG and EG reduced indifferent degree.(3) Soil microbial number showed significantly positive correlation with aboveground biomass. Under different grazing intensities, soil microbial number showed ahighly positive correlation with soil organic carbon, temperature and soil water content

Mots clés : Desert Steppe Biomass Seasonal Dynamics Influence Factors CarbonStorage Spatial Distribution

Présentation (Dissertation topics)

Page publiée le 1er avril 2014, mise à jour le 10 janvier 2018