As an important component of ecosystem carbon（C） budgets, soil carbon dioxide（CO2） flux is determined by a combination of a series of biotic and abiotic processes. Although there is evidence showing that the abiot...As an important component of ecosystem carbon（C） budgets, soil carbon dioxide（CO2） flux is determined by a combination of a series of biotic and abiotic processes. Although there is evidence showing that the abiotic component can be important in total soil CO2 flux（R（total））, its relative importance has never been systematically assessed. In this study, after comparative measurements of CO2 fluxes on sterilized and natural soils, the R（total） was partitioned into biotic flux（R（biotic）） and abiotic flux（R（abiotic）） across a broad range of land-cover types（including eight sampling sites： cotton field, hops field, halophyte garden, alkaline land, reservoir edge, native saline desert, dune crest and interdune lowland） in Gurbantunggut Desert, Xinjiang, China. The relative contribution of R（abiotic） to R（total）, as well as the temperature dependency and predominant factors for R（total）, R（biotic） and R（abiotic）, were analyzed. Results showed that R（abiotic） always contributed to R（total） for all of the eight sampling sites, but the degree or magnitude of contribution varied greatly. Specifically, the ratio of R（abiotic） to R（total） was very low in cotton field and hops field and very high in alkaline land and dune crest. Statistically, the ratio of R（abiotic） to R（total） logarithmically increased with decreasing R（biotic）, suggesting that R（abiotic） strongly affected R（total） when R（biotic） was low. This pattern confirms that soil CO2 flux is predominated by biotic processes in most soils, but abiotic processes can also be dominant when biotic processes are weak. On a diurnal basis, R（abiotic） cannot result in net gain or net loss of CO2, but its effect on transient CO2 flux was significant. Temperature dependency of R（total） varied among the eight sampling sites and was determined by the predominant processes（abiotic or biotic） of CO2 flux. Specifically, R（biotic） was driven by soil temperature while R（abiotic） was regulated by the change in soil temperature（ΔT）. Namely, declining temperature（ΔT0） resulted in positive R（abiotic）（i.e., CO2 released from soil）. Without recognition of R（abiotic）, R（biotic） would be overestimated for the daytime and underestimated for the nighttime. Although R（abiotic） may not change the sum or the net value of daily soil CO2 exchange and may not directly constitute a C sink, it can significantly alter the transient apparent soil CO2 flux, either in magnitude or in temperature dependency. Thus, recognizing the fact that abiotic component in R（total） exists widely in soils has widespread consequences for the understanding of C cycling.展开更多
Soil CO 2 emission from an arable soil was measured by closed chamber method to quantify year round soil flux and to develop an equation to predict flux using soil temperature, dissolved organic carbon(DOC) and soil...Soil CO 2 emission from an arable soil was measured by closed chamber method to quantify year round soil flux and to develop an equation to predict flux using soil temperature, dissolved organic carbon(DOC) and soil moisture content. Soil CO 2 flux, soil temperature, DOC and soil moisture content were determined on selected days during the experiment from August 1999 to July 2000, at the Ecological Station of Red Soil, the Chinese Academy of Sciences, in a subtropical region of China. Soil CO 2 fluxes were generally higher in summer and autumn than in winter and spring, and had a seasonal pattern more similar to soil temperature and DOC than soil moisture. The estimation was 2 23 kgCO 2/(m 2·a) for average annual soil CO 2 flux. Regressed separately, the reasons for soil flux variability were 86 6% from soil temperature, 58 8% from DOC, and 26 3% from soil moisture, respectively. Regressed jointly, a multiple equation was developed by the above three variables that explained approximately 85 2% of the flux variance, however by stepwise regression, soil temperature was the dominant affecting soil flux. Based on the exponential equation developed from soil temperature, the predicted annual flux was 2 49 kgCO 2/(m 2·a), and essentially equal to the measured one. It is suggested the exponential relationship between soil flux and soil temperature could be used for accurately predicting soil CO 2 flux from arable soil in subtropical regions of China.展开更多
Safe and economical disposal of paper mill sludge is a key consideration for forest products industry. A study was conducted to examine the effects of amendments of sludge and nutrients on soil surface CO2 flux （Rs）...Safe and economical disposal of paper mill sludge is a key consideration for forest products industry. A study was conducted to examine the effects of amendments of sludge and nutrients on soil surface CO2 flux （Rs） in northern hardwood forests and to quantify the relationship among Rs, soil temperature, and moisture in these stands. The experiment was a randomized complete block design that included sludge-amended, fertilized, and control treatments in sugar maple （Acer saccharum Marsh） dominated hardwood forests in the Upper Peninsula of Michigan, USA. Results showed that Rs was positively correlated to soil temperature （R^2 = 0.80, p 〈 0.001）, but was poorly correlated to soil moisture. Soil moisture positively affected the Rs only in the sludge-amended treatment. The Rs was significantly greater in the sludge-amended treatment than in the fertilized （p = 0.033） and the control （p = 0.048） treatments. The maximum Rs in the sludge-amended treatment was 8.8 μmol CO2 · m^ 2. s^-1, 91% and 126% greater than those in the fertilized （4.6 μmol CO2 · m^-2· s^-1） and control （3.9 μmol CO2· m^- 2· s^-1） treatments, respectively. The Rs did not differ significantly between the fertilized and control treatments. The difference in Rs between sludge-amended and the other treatments decreased with time following treatment.展开更多
采用静态箱-气相色谱法对浙江省临安市玲珑山风景区天然阔叶林和由天然阔叶林改造的杉木人工林的土壤呼吸进行1年的定位监测.结果表明：天然阔叶林和杉木人工林土壤CO2排放速率均呈现一致的季节性变化规律即夏秋季高、冬春季低;天然阔...采用静态箱-气相色谱法对浙江省临安市玲珑山风景区天然阔叶林和由天然阔叶林改造的杉木人工林的土壤呼吸进行1年的定位监测.结果表明：天然阔叶林和杉木人工林土壤CO2排放速率均呈现一致的季节性变化规律即夏秋季高、冬春季低;天然阔叶林和杉木人工林土壤CO2排放速率分别为20.0-111.3和4.1-118.6 mg C·m-2·h-1;天然阔叶林土壤CO2年累积排放通量（16.46 t CO2·hm-2·a-1）显著高于杉木人工林（11.99 t CO2·hm-2·a-1）.天然阔叶林和杉木人工林土壤CO2排放速率与土壤含水量均没有显著相关性,而与5cm处土壤温度呈显著指数相关,Q10值分别为1.44和2.97;天然阔叶林土壤CO2排放速率与土壤水溶性碳（WSOC）含量无显著相关性,杉木人工林土壤CO2排放速率与WSOC含量呈显著相关.天然阔叶林转换为杉木人工林显著降低了土壤CO2排放,提高了土壤呼吸对环境因子的敏感性.展开更多
基金supported by the National Natural Science Foundation of China (41301279, 41201041)the International Science & Technology Cooperation Program of China (2010DFA92720)the Knowledge Innovation Project of the Chinese Academy of Sciences (KZCX2-YW-T09)
文摘As an important component of ecosystem carbon（C） budgets, soil carbon dioxide（CO2） flux is determined by a combination of a series of biotic and abiotic processes. Although there is evidence showing that the abiotic component can be important in total soil CO2 flux（R（total））, its relative importance has never been systematically assessed. In this study, after comparative measurements of CO2 fluxes on sterilized and natural soils, the R（total） was partitioned into biotic flux（R（biotic）） and abiotic flux（R（abiotic）） across a broad range of land-cover types（including eight sampling sites： cotton field, hops field, halophyte garden, alkaline land, reservoir edge, native saline desert, dune crest and interdune lowland） in Gurbantunggut Desert, Xinjiang, China. The relative contribution of R（abiotic） to R（total）, as well as the temperature dependency and predominant factors for R（total）, R（biotic） and R（abiotic）, were analyzed. Results showed that R（abiotic） always contributed to R（total） for all of the eight sampling sites, but the degree or magnitude of contribution varied greatly. Specifically, the ratio of R（abiotic） to R（total） was very low in cotton field and hops field and very high in alkaline land and dune crest. Statistically, the ratio of R（abiotic） to R（total） logarithmically increased with decreasing R（biotic）, suggesting that R（abiotic） strongly affected R（total） when R（biotic） was low. This pattern confirms that soil CO2 flux is predominated by biotic processes in most soils, but abiotic processes can also be dominant when biotic processes are weak. On a diurnal basis, R（abiotic） cannot result in net gain or net loss of CO2, but its effect on transient CO2 flux was significant. Temperature dependency of R（total） varied among the eight sampling sites and was determined by the predominant processes（abiotic or biotic） of CO2 flux. Specifically, R（biotic） was driven by soil temperature while R（abiotic） was regulated by the change in soil temperature（ΔT）. Namely, declining temperature（ΔT0） resulted in positive R（abiotic）（i.e., CO2 released from soil）. Without recognition of R（abiotic）, R（biotic） would be overestimated for the daytime and underestimated for the nighttime. Although R（abiotic） may not change the sum or the net value of daily soil CO2 exchange and may not directly constitute a C sink, it can significantly alter the transient apparent soil CO2 flux, either in magnitude or in temperature dependency. Thus, recognizing the fact that abiotic component in R（total） exists widely in soils has widespread consequences for the understanding of C cycling.
文摘Soil CO 2 emission from an arable soil was measured by closed chamber method to quantify year round soil flux and to develop an equation to predict flux using soil temperature, dissolved organic carbon(DOC) and soil moisture content. Soil CO 2 flux, soil temperature, DOC and soil moisture content were determined on selected days during the experiment from August 1999 to July 2000, at the Ecological Station of Red Soil, the Chinese Academy of Sciences, in a subtropical region of China. Soil CO 2 fluxes were generally higher in summer and autumn than in winter and spring, and had a seasonal pattern more similar to soil temperature and DOC than soil moisture. The estimation was 2 23 kgCO 2/(m 2·a) for average annual soil CO 2 flux. Regressed separately, the reasons for soil flux variability were 86 6% from soil temperature, 58 8% from DOC, and 26 3% from soil moisture, respectively. Regressed jointly, a multiple equation was developed by the above three variables that explained approximately 85 2% of the flux variance, however by stepwise regression, soil temperature was the dominant affecting soil flux. Based on the exponential equation developed from soil temperature, the predicted annual flux was 2 49 kgCO 2/(m 2·a), and essentially equal to the measured one. It is suggested the exponential relationship between soil flux and soil temperature could be used for accurately predicting soil CO 2 flux from arable soil in subtropical regions of China.
基金The research was funded by a NCASI grant to S.T. Gower. Wang CK was supported by Innovated Talent Program of Northeast Forestry University (2004-07)
文摘Safe and economical disposal of paper mill sludge is a key consideration for forest products industry. A study was conducted to examine the effects of amendments of sludge and nutrients on soil surface CO2 flux （Rs） in northern hardwood forests and to quantify the relationship among Rs, soil temperature, and moisture in these stands. The experiment was a randomized complete block design that included sludge-amended, fertilized, and control treatments in sugar maple （Acer saccharum Marsh） dominated hardwood forests in the Upper Peninsula of Michigan, USA. Results showed that Rs was positively correlated to soil temperature （R^2 = 0.80, p 〈 0.001）, but was poorly correlated to soil moisture. Soil moisture positively affected the Rs only in the sludge-amended treatment. The Rs was significantly greater in the sludge-amended treatment than in the fertilized （p = 0.033） and the control （p = 0.048） treatments. The maximum Rs in the sludge-amended treatment was 8.8 μmol CO2 · m^ 2. s^-1, 91% and 126% greater than those in the fertilized （4.6 μmol CO2 · m^-2· s^-1） and control （3.9 μmol CO2· m^- 2· s^-1） treatments, respectively. The Rs did not differ significantly between the fertilized and control treatments. The difference in Rs between sludge-amended and the other treatments decreased with time following treatment.
文摘采用静态箱-气相色谱法对浙江省临安市玲珑山风景区天然阔叶林和由天然阔叶林改造的杉木人工林的土壤呼吸进行1年的定位监测.结果表明：天然阔叶林和杉木人工林土壤CO2排放速率均呈现一致的季节性变化规律即夏秋季高、冬春季低;天然阔叶林和杉木人工林土壤CO2排放速率分别为20.0-111.3和4.1-118.6 mg C·m-2·h-1;天然阔叶林土壤CO2年累积排放通量（16.46 t CO2·hm-2·a-1）显著高于杉木人工林（11.99 t CO2·hm-2·a-1）.天然阔叶林和杉木人工林土壤CO2排放速率与土壤含水量均没有显著相关性,而与5cm处土壤温度呈显著指数相关,Q10值分别为1.44和2.97;天然阔叶林土壤CO2排放速率与土壤水溶性碳（WSOC）含量无显著相关性,杉木人工林土壤CO2排放速率与WSOC含量呈显著相关.天然阔叶林转换为杉木人工林显著降低了土壤CO2排放,提高了土壤呼吸对环境因子的敏感性.
