The methane concentration profile from -1.5m depth in soil to 32m height in air was measured in alpine steppe lo-cated in the permafrost area. Methane concentrations showed widely variations both in air and in soil du...The methane concentration profile from -1.5m depth in soil to 32m height in air was measured in alpine steppe lo-cated in the permafrost area. Methane concentrations showed widely variations both in air and in soil during the study period. The mean concentrations in atmosphere were all higher than those in soil, and the highest methane concentration was found in air at the height of 16m with the lowest concentration occur-ring at the depth of 1.5m in soil. The variations of atmospheric methane concentrations did not show any clear pattern both temporally and spatially, although they exhibited a more steady-stable state than those in soil. During the seasonal variations, the methane concentrations at different depths in soil were sig-nificantly correlated (R2>0.6) with each other comparing to the weak correlations (R2<0.2) between the atmospheric concentra-tions at different heights. Mean methane concentrations in soil significantly decreased with depth. This was the compositive influence of the decreasing production rates and the increasing methane oxidation rates, which was caused by the descent soil moisture with depth. Although the methane concentrations at all depths varied widely during the growing season, they showed very distinct temporal variations in the non-growing season. It was indicated from the literatures that methane oxidation rates were positively correlated with soil temperature. The higher methane concentrations in soil during the winter were deter-mined by the lower methane oxidation rates with decreasing soil temperatures, whereas methane production rates had no reaction to the lower temperature. Relations between methane contribution and other environmental factors were not discussed in this paper for lacking of data, which impulse us to carry out further and more detailed studies in this unique area.展开更多
The Qinghai-Tibetan Plateau is the highest biogeographic unit on earth and widely regarded as its ‘third pole＇.The high-altitude,frigid and arid alpine ecosystems that form the Plateau are extremely sensitive to cli...The Qinghai-Tibetan Plateau is the highest biogeographic unit on earth and widely regarded as its ‘third pole＇.The high-altitude,frigid and arid alpine ecosystems that form the Plateau are extremely sensitive to climate change and human disturbance.Unsurprisingly,the Plateau is therefore a global epicenter of ecological and global change research and provides the ideal conditions and context to study the impacts of global change.Ecological research conducted on the Plateau can be partitioned into four developmental and chronological phases,beginning with the gathering of primitive knowledge and progressing towards a description of mechanistic processes.Throughout the course of Plateau research paradigm shifts from standalone surveys of biogeographic patterns to fixed monitoring and mechanism research;from isolated population,community and ecosystem approaches to more integrated,multidisciplinary research;and from pure theoretical research to an emphasis on effective resource utilization and sustainable development.Future ecological research will likely pay increasing attention to quantifying the impacts of climate warming and human activity on ecosystem change,and climate and ecosystem feedback processes.Multidisciplinary and comprehensive research should be strengthened amongst fields such as ecosystem ecology,physical geography,environmental science and remote sensing in order to support climate change adaptation and sustainable development in this fragile and unique region.展开更多
基金funded by The National Basic Research Program (Grant No. G1998040800)Pre-studies project of National Basic Research Program (Grant No. 2005CCA05500)
文摘The methane concentration profile from -1.5m depth in soil to 32m height in air was measured in alpine steppe lo-cated in the permafrost area. Methane concentrations showed widely variations both in air and in soil during the study period. The mean concentrations in atmosphere were all higher than those in soil, and the highest methane concentration was found in air at the height of 16m with the lowest concentration occur-ring at the depth of 1.5m in soil. The variations of atmospheric methane concentrations did not show any clear pattern both temporally and spatially, although they exhibited a more steady-stable state than those in soil. During the seasonal variations, the methane concentrations at different depths in soil were sig-nificantly correlated (R2>0.6) with each other comparing to the weak correlations (R2<0.2) between the atmospheric concentra-tions at different heights. Mean methane concentrations in soil significantly decreased with depth. This was the compositive influence of the decreasing production rates and the increasing methane oxidation rates, which was caused by the descent soil moisture with depth. Although the methane concentrations at all depths varied widely during the growing season, they showed very distinct temporal variations in the non-growing season. It was indicated from the literatures that methane oxidation rates were positively correlated with soil temperature. The higher methane concentrations in soil during the winter were deter-mined by the lower methane oxidation rates with decreasing soil temperatures, whereas methane production rates had no reaction to the lower temperature. Relations between methane contribution and other environmental factors were not discussed in this paper for lacking of data, which impulse us to carry out further and more detailed studies in this unique area.
文摘The Qinghai-Tibetan Plateau is the highest biogeographic unit on earth and widely regarded as its ‘third pole＇.The high-altitude,frigid and arid alpine ecosystems that form the Plateau are extremely sensitive to climate change and human disturbance.Unsurprisingly,the Plateau is therefore a global epicenter of ecological and global change research and provides the ideal conditions and context to study the impacts of global change.Ecological research conducted on the Plateau can be partitioned into four developmental and chronological phases,beginning with the gathering of primitive knowledge and progressing towards a description of mechanistic processes.Throughout the course of Plateau research paradigm shifts from standalone surveys of biogeographic patterns to fixed monitoring and mechanism research;from isolated population,community and ecosystem approaches to more integrated,multidisciplinary research;and from pure theoretical research to an emphasis on effective resource utilization and sustainable development.Future ecological research will likely pay increasing attention to quantifying the impacts of climate warming and human activity on ecosystem change,and climate and ecosystem feedback processes.Multidisciplinary and comprehensive research should be strengthened amongst fields such as ecosystem ecology,physical geography,environmental science and remote sensing in order to support climate change adaptation and sustainable development in this fragile and unique region.
