Fluxes of nitrous oxide (N2O) from different land use patterns (matured forest, secondary forest, grassland and cropland) in a subtropical karst region of Guizhou Province, Southwest China, were measured for one year ...Fluxes of nitrous oxide (N2O) from different land use patterns (matured forest, secondary forest, grassland and cropland) in a subtropical karst region of Guizhou Province, Southwest China, were measured for one year with a closed static chamber technique and by gas chromatography. The results showed that soil under different land uses was a source of atmospheric N2O. The cropland was a source with relatively high N2O as compared to forest and grassland, but no significant differences were observed. N2O emissions from soils varied with land use change and fertilizer application. There were two peaks of N2O flux occurred following the combination of two obvious precipitation and fertilizer events in the cultivated land. Converting from the matured forest to secondary forest tended to increase annual emissions of N2O (from 1.40 to 1.65 kg N ha -1 a -1 ), while changing land use from secondary forest to scattered grassland tended to decrease annual emissions of N2O slightly (from 1.65 to 1.45 kg N ha -1 a -1 ). Our range of cumulative annual N2O emission across different land uses (1.40-1.91 kg N ha -1 a -1 ) in a karst region is in general agreement with previously published data in a non-karst region. However, in the maize field, N2O emission factor (EF) was 0.34% for fertilizer application, which is about 71.2% lower than the IPCC default value. It is suggested that current IPCC (Intergovernmental Panel on Climate Change) EF methodology could overestimate N2O emission from the karstic cropland. Anyway, the N2O emission from cropland in the karst region would contribute significantly to the global N2O budget, so reducing fertilization frequency during the crop growing season could lead to a decrease in N2O emission in the whole year.展开更多
Accurate estimation of forest carbon storage is crucial in understanding global and regional carbon cycles and projecting future ecological and economic scenarios.Guizhou is the largest karst landform province in Chin...Accurate estimation of forest carbon storage is crucial in understanding global and regional carbon cycles and projecting future ecological and economic scenarios.Guizhou is the largest karst landform province in China;61.9% of its land area is characterized as karst. However,monitoring its field biomass and carbon storage is difficult.This study synthesized and analyzed a comprehensive database of direct field observations of forest vegetation and soil carbon storage in Guizhou Province by using data from existing literature. The total vegetation carbon storage in Guizhou Province was 488.170 TgC, the average vegetation carbon density(VCD) was 27.866 MgC hm^(-2), the total amount of soil organic carbon(SOC)(20 cm) was 1017.364 TgC, and the average SOC density was 58.074 MgC hm^(-2). Among all vegetation types, needleleaf forest had the highest vegetation carbon stocks, and scrub presented the highest SOC storage. The vegetation and SOC storage values of the karst landform were 282.352 and 614.825 TgC, respectively, which were higher than thoseof the non-karst landform. VCD was concentrated at 10–40 MgC hm^(-2), and SOC density was concentrated at 40–60, 60–80, and 80–100 MgC hm^(-2). This comprehensive regional data synthesis and analysis based on direct field measurement of vegetation and soil will improve our understanding of the forest carbon cycle in karst landforms under a changing climate.展开更多
Huainan coal field as main object,investigation of Karstic hydrogeological con- ditions were developed in Huainan structureal unit,and the basic conditions,features and rules of Karstic growth were summarized.Geology ...Huainan coal field as main object,investigation of Karstic hydrogeological con- ditions were developed in Huainan structureal unit,and the basic conditions,features and rules of Karstic growth were summarized.Geology background and causes of Karstic col- lapse columns were analyzed.Combined with ancient physiognomy,environment and li- tho-facies features.After studying synthetically Karstic collapse columns,shape of col- lapse body,filling feature,hydrodynamic condition and agglutinate material in Huainan area,considering mine hydrogeological conditions of Xuhuai coal field and referenced Karstic collapse columns characters of other mines in North China,the internal thermal origin theory is elementarily formed for Karstic collapse columns extrinsic cycle can not operate smoothly.Finaly,three aspects including distributing features of different kinds of Karstic collapse columns in north China type coal field,conditions of Karstic collapse col- umns origined from internal thermal with no smoothly extrinsic cycle,mechanics of causes were analyzed and demonstrated.展开更多
基金financially supported jointly by the National Natural Science Foundation of China (Nos. 41021062, 40872212,41103078)the Key Agriculture R&D Program of Guizhou Province (Qian Science co-NY [2011] No.3079)+1 种基金the Strategic Priority Research Program of the Chinese Academy of Sciences (XDA05070400)the Natural Science Foundation of Guizhou Province(Qian Science co-J [2011] No. 2054)
文摘Fluxes of nitrous oxide (N2O) from different land use patterns (matured forest, secondary forest, grassland and cropland) in a subtropical karst region of Guizhou Province, Southwest China, were measured for one year with a closed static chamber technique and by gas chromatography. The results showed that soil under different land uses was a source of atmospheric N2O. The cropland was a source with relatively high N2O as compared to forest and grassland, but no significant differences were observed. N2O emissions from soils varied with land use change and fertilizer application. There were two peaks of N2O flux occurred following the combination of two obvious precipitation and fertilizer events in the cultivated land. Converting from the matured forest to secondary forest tended to increase annual emissions of N2O (from 1.40 to 1.65 kg N ha -1 a -1 ), while changing land use from secondary forest to scattered grassland tended to decrease annual emissions of N2O slightly (from 1.65 to 1.45 kg N ha -1 a -1 ). Our range of cumulative annual N2O emission across different land uses (1.40-1.91 kg N ha -1 a -1 ) in a karst region is in general agreement with previously published data in a non-karst region. However, in the maize field, N2O emission factor (EF) was 0.34% for fertilizer application, which is about 71.2% lower than the IPCC default value. It is suggested that current IPCC (Intergovernmental Panel on Climate Change) EF methodology could overestimate N2O emission from the karstic cropland. Anyway, the N2O emission from cropland in the karst region would contribute significantly to the global N2O budget, so reducing fertilization frequency during the crop growing season could lead to a decrease in N2O emission in the whole year.
基金financially supported by National Natural Science Foundation of China (Nos. 41471049 and 31870462)
文摘Accurate estimation of forest carbon storage is crucial in understanding global and regional carbon cycles and projecting future ecological and economic scenarios.Guizhou is the largest karst landform province in China;61.9% of its land area is characterized as karst. However,monitoring its field biomass and carbon storage is difficult.This study synthesized and analyzed a comprehensive database of direct field observations of forest vegetation and soil carbon storage in Guizhou Province by using data from existing literature. The total vegetation carbon storage in Guizhou Province was 488.170 TgC, the average vegetation carbon density(VCD) was 27.866 MgC hm^(-2), the total amount of soil organic carbon(SOC)(20 cm) was 1017.364 TgC, and the average SOC density was 58.074 MgC hm^(-2). Among all vegetation types, needleleaf forest had the highest vegetation carbon stocks, and scrub presented the highest SOC storage. The vegetation and SOC storage values of the karst landform were 282.352 and 614.825 TgC, respectively, which were higher than thoseof the non-karst landform. VCD was concentrated at 10–40 MgC hm^(-2), and SOC density was concentrated at 40–60, 60–80, and 80–100 MgC hm^(-2). This comprehensive regional data synthesis and analysis based on direct field measurement of vegetation and soil will improve our understanding of the forest carbon cycle in karst landforms under a changing climate.
基金the China National Program on Key Basic Research Project(2006CB202209)
文摘Huainan coal field as main object,investigation of Karstic hydrogeological con- ditions were developed in Huainan structureal unit,and the basic conditions,features and rules of Karstic growth were summarized.Geology background and causes of Karstic col- lapse columns were analyzed.Combined with ancient physiognomy,environment and li- tho-facies features.After studying synthetically Karstic collapse columns,shape of col- lapse body,filling feature,hydrodynamic condition and agglutinate material in Huainan area,considering mine hydrogeological conditions of Xuhuai coal field and referenced Karstic collapse columns characters of other mines in North China,the internal thermal origin theory is elementarily formed for Karstic collapse columns extrinsic cycle can not operate smoothly.Finaly,three aspects including distributing features of different kinds of Karstic collapse columns in north China type coal field,conditions of Karstic collapse col- umns origined from internal thermal with no smoothly extrinsic cycle,mechanics of causes were analyzed and demonstrated.
