红河干热河谷土地利用变化下土壤碳排放 时空变化及机制研究

	红河干热河谷土地利用变化下土壤碳排放时空变化及机制研究; Study of spatial-temporal changes of soil Carbon emission and mechanism under land use change in dry-hot valley
	王正洪
导师	许建初
摘要	Soil CO2 emissions caused by land-use change (LUC) are now the second-largest source of anthropogenic greenhouse gases after fossil fuels and are continually increasing. Moreover, CO2 emissions from soil are increasingly considered a valuable indicator of overall soil health. Thus, the impact of LUC on CO2 emissions and soil carbon reserves is in need of increased attention. Microbial communities mediate multiple processes of soil carbon cycling (such as carbon degradation), and microbial geography indicates that differences in ecosystems and land-use types will alter the main factors affecting the distribution of bacterial communities. Given the heterogeneity of soil environments across variables such as differences in soil nutrient level, microclimate, vegetation cover, and management practices, changes in CO2 emissions as well as its main influencing factors under LUC in different ecosystems have been controversial. Furthermore, little is known about the effects of LUC on soil CO2 emissions and other ecological functions in ecologically fragile areas (e.g., dry-hot valley regions). Based on local government efforts to develop dry-hot regions, this study was conducted to investigate the effects of LUC on the fragile ecosystems of dry-hot valleys. Natural degraded grassland, newly transformed farmland as well as farmland converted with different chronosequences were selected. Under investigation were ecological and soil metagenomics, the effects and mechanisms of LUC and its chronosequences on soil CO2 emissions, chemical and functional characteristics as well as microbial communities. The main conclusions were as follow: （1）Effects of LUC on soil CO2 efflux and microbial community characteristics Most soil chemical properties remained unaffected after conversion due to generally low regional nutrient levels. Principal component analysis revealed a decline in soil heterogeneity of the selected properties (pH, SOC, TN, TP, AP), which will be useful for future unified soil management. Compared to grassland, CO2 efflux in mango plantations increased by 20-69% after LUC. This common trend could be seen in soil CO2 efflux across an elevation gradient. The temperature sensitivity (Q10: 0.68~1.98) of CO2 efflux in both land use types was low due to low soil moisture at high temperatures. Soil water content was the primary factor affecting CO2 efflux in the dry-hot valley region, followed by microbial biomass carbon. Metagenomics data revealed significant differences in soil microbial community composition before and after LUC. Bacteria community diversity decreased after LUC, and the OTUs belonging to the phyla Actinobacteria, Bacteroidetes, and Proteobacteria showed clear enrichment, yet a wide range of low abundance phylum (26) generally decreased. Classification at the genus level had a high accuracy in differentiating bacterial communities among land types, and 22 genera were capable of being used as biomarker genera. Results from db-RDA indicate
	2021-05
文献类型	学位论文
条目标识符	http://ir.kib.ac.cn/handle/151853/74539
专题	昆明植物所硕博研究生毕业学位论文
推荐引用方式 GB/T 7714	王正洪. 红河干热河谷土地利用变化下土壤碳排放时空变化及机制研究, Study of spatial-temporal changes of soil Carbon emission and mechanism under land use change in dry-hot valley[D],2021.

条目包含的文件
文件名称/大小	文献类型	版本类型	开放类型	使用许可
王正洪-王正洪-终稿上传3ec6e87e（10085KB）	学位论文		限制开放	CC BY-NC-SA	请求全文