Soils play a critical role in the global carbon cycle, and can be major source or sink of CO2 depending upon land use, vegetation type and soil management practices. Fine roots are important component of a forest ecos...Soils play a critical role in the global carbon cycle, and can be major source or sink of CO2 depending upon land use, vegetation type and soil management practices. Fine roots are important component of a forest ecosystem in terms of water and nutrient uptake. In this study the effects of thinning and litter fall removal on fine root production and soil organic carbon content were examined in 20-year-old Masson pine （Pinus resinosa） plantations in Huitong, Hunan Province of China in the growing seasons of 2004 and 2005. The results showed that fine root production was significantly lower in the thinning plots than in the control plots, with a decrease of 58% and 14% in 2004 and 2005 growing seasons, respectively. Litter fall removal significantly increased fine root production by 14% in 2004. Soil temperature （Tsoil） and soil moisture （Msoil） were higher in the thinning plots than those in the controls. Litter fall removal had significant effects on Tsoil and Msoil. Soil organic carbon content was higher in the thinning plots but was lower in the plots with litter fall removal compared with that in the controls. Our results also indicated that annual production of fine roots resulted in small carbon accumulation in the upper layers of the soil, and removal of tree by thinning resulted in a significant increase of carbon storage in Masson pine plantations.展开更多
This study investigates the stratification of soil thermal properties induced by soil organic carbon (SOC) and its impacts on the parameterization of the thermal properties. Soil parameters were measured for alpine gr...This study investigates the stratification of soil thermal properties induced by soil organic carbon (SOC) and its impacts on the parameterization of the thermal properties. Soil parameters were measured for alpine grassland stations and North China flux stations, with a total of 34 stations and 77 soil profiles. Measured data indicate that the topsoils of alpine grasslands contain high SOC contents than underlying soil layers, which leads to higher soil porosity values and lower thermal conductivity and bulk density values in the topsoils. However, this stratification is not evident at the lowland stations due to low SOC contents. Evaluations against measured data show that three thermal conductivity schemes used in land surface models severely overestimate the values for soils with high SOC content (i.e. topsoils of alpine grassland), but they are better for soils with low SOC content. A new parameterization is then developed to take the impacts of SOC into account. The new one can well estimate the soil thermal conductivity values in both low and high SOC content cases, and therefore, it is a potential candidate of thermal conductivity scheme to be used in land surface models.展开更多
基金Supported by the "948" Grant of the National Forestry Administration of China (No.2007-4-19)the Special Grantof Chinese Forestry Public Benefits (Nos.200804030 and 2007-4-15)the Provincial Fund for Distinguished Young Scholars of Hunan, China (No.07JJ1004)
文摘Soils play a critical role in the global carbon cycle, and can be major source or sink of CO2 depending upon land use, vegetation type and soil management practices. Fine roots are important component of a forest ecosystem in terms of water and nutrient uptake. In this study the effects of thinning and litter fall removal on fine root production and soil organic carbon content were examined in 20-year-old Masson pine （Pinus resinosa） plantations in Huitong, Hunan Province of China in the growing seasons of 2004 and 2005. The results showed that fine root production was significantly lower in the thinning plots than in the control plots, with a decrease of 58% and 14% in 2004 and 2005 growing seasons, respectively. Litter fall removal significantly increased fine root production by 14% in 2004. Soil temperature （Tsoil） and soil moisture （Msoil） were higher in the thinning plots than those in the controls. Litter fall removal had significant effects on Tsoil and Msoil. Soil organic carbon content was higher in the thinning plots but was lower in the plots with litter fall removal compared with that in the controls. Our results also indicated that annual production of fine roots resulted in small carbon accumulation in the upper layers of the soil, and removal of tree by thinning resulted in a significant increase of carbon storage in Masson pine plantations.
基金supported by National Natural Science Foundation of China (Grant No. 41105003)Key Project of Chinese Academy of Sciences (Grant No.KZCX2-YW-Q10-2)+1 种基金National Natural Science Foundation of China (Grant No. 91025004)Open Fund from the State Key Laboratory of Remote Sensing Science (Grant No. OFSLRSS201108) that is cosponsored by the Institute of Remote Sensing Applications of Chinese Academy of Sciences and Beijing Normal University
文摘This study investigates the stratification of soil thermal properties induced by soil organic carbon (SOC) and its impacts on the parameterization of the thermal properties. Soil parameters were measured for alpine grassland stations and North China flux stations, with a total of 34 stations and 77 soil profiles. Measured data indicate that the topsoils of alpine grasslands contain high SOC contents than underlying soil layers, which leads to higher soil porosity values and lower thermal conductivity and bulk density values in the topsoils. However, this stratification is not evident at the lowland stations due to low SOC contents. Evaluations against measured data show that three thermal conductivity schemes used in land surface models severely overestimate the values for soils with high SOC content (i.e. topsoils of alpine grassland), but they are better for soils with low SOC content. A new parameterization is then developed to take the impacts of SOC into account. The new one can well estimate the soil thermal conductivity values in both low and high SOC content cases, and therefore, it is a potential candidate of thermal conductivity scheme to be used in land surface models.
