Plant root-derived carbon(C)inputs(I_(root))are the primary source of C in mineral bulk soil.However,a fraction of I_(root)may lose quickly(I_(loss),e.g.,via rhizosphere microbial respiration,leaching and fauna feedin...Plant root-derived carbon(C)inputs(I_(root))are the primary source of C in mineral bulk soil.However,a fraction of I_(root)may lose quickly(I_(loss),e.g.,via rhizosphere microbial respiration,leaching and fauna feeding)without contributing to long-term bulk soil C storage,yet this loss has never been quantified,particularly on a global scale.In this study we integrated three observational global data sets including soil radiocarbon content,allocation of photo synthetically assimilated C,and root biomass distribution in 2,034 soil profiles to quantify I_(root)and its contribution to the bulk soil C pool.We show that global average I_(root)in the 0-200 cm soil profile is 3.5 Mg ha^(-1)yr^(-1),~80%of which(i.e.,I_(loss))is lost rather than co ntributing to long-term bulk soil C storage.I_(root)decreases exponentially with soil depth,and the top 20 cm soil contains>60%of total I_(root).Actual C input contributing to long-term bulk soil storage(i.e.,I_(root)-I_(loss))shows a similar depth distribution to I_(root).We also map I_(loss)and its depth distribution across the globe.Our results demonstrate the global significance of direct C losses which limit the contribution of I_(root)to bulk soil C storage;and provide spatially explicit data to facilitate reliable soil C predictions via separating direct C losses from total root-derived C inputs.展开更多
Aims Resource allocation in plants can be strongly affected by competition.Besides plant–plant interactions,terrestrial plants compete with the soil bacterial community over nutrients.Since the bacterial communities ...Aims Resource allocation in plants can be strongly affected by competition.Besides plant–plant interactions,terrestrial plants compete with the soil bacterial community over nutrients.Since the bacterial communities cannot synthesize their own energy sources,they are dependent on external carbon sources.Unlike the effect of overall amounts of carbon(added to the soil)on plant performance,the effect of fine scale temporal variation in soil carbon inputs on the bacterial biomass and its cascading effects on plant growth are largely unknown.We hypothesize that continuous carbon supply(small temporal variance)will result in a relatively constant bacterial biomass that will effectively compete with plants for nutrients.On the other hand,carbon pulses(large temporal variance)are expected to cause oscillations in bacterial biomass,enabling plants temporal escape from competition and possibly enabling increased growth.We thus predicted that continuous carbon supply would increase root allocation at the expense of decreased reproductive output.We also expected this effect to be noticeable only when sufficient nutrients were present in the soil.Methods Wheat plants were grown for 64 days in pots containing either sterilized or inoculated soils,with or without slow-release fertilizer,subjected to one of the following six carbon treatments:daily(1.5mg glucose),every other day(3mg glucose),4 days(6mg glucose),8 days(12mg glucose),16 days(24mg glucose)and no carbon control.Important Findings Remarkably,carbon pulses(every 2–16 days)led to increased reproductive allocation at the expense of decreased root allocation in plants growing in inoculated soils.Consistent with our prediction,these effects were noticeable only when sufficient nutrients were present in the soil.Furthermore,soil inoculation in plants subjected to low nutrient availability resulted in decreased total plant biomass.We interpret this to mean that when the amount of available nutrients is low,these nutrients are mainly used by the bacterial community.Our results show that temporal variation in soil carbon inputs may play an important role in aboveground–belowground interactions,affecting plant resource allocation.展开更多
Becoming the world's largest emitter of carbon makes China the object of criticism;however,people may ignore the fact that when China exports low-carbon products,the carbon emissions have been left in the meanwhil...Becoming the world's largest emitter of carbon makes China the object of criticism;however,people may ignore the fact that when China exports low-carbon products,the carbon emissions have been left in the meanwhile,forming the so-called"embodied carbon".Using the input-output model,this paper analyzes the carbon emission intensity and amount of embodied carbon of various sectors in China's export trade in 2002 and 2007,and filters out high carbon emission sectors.In addition,this paper also points out the problem of carbon emissions'international transfer from developed countries to China through the analysis of national and regional flow of export carbon emissions and changing of the proportion of emissions for exports relative to total emissions,and explains the reason that caused carbon transfer to China by using the treadmill of production theory.Based on that,this paper proposes some measures for carbon reduction in China from the foreign trade perspective.展开更多
Under the pressure of sustained growth in energy consumption in China,the implementation of a carbon pricing mechanism is an effective economic policy measure for promoting emission reduction,as well as a hotspot of r...Under the pressure of sustained growth in energy consumption in China,the implementation of a carbon pricing mechanism is an effective economic policy measure for promoting emission reduction,as well as a hotspot of research among scholars and policy makers.In this paper,the effects of carbon prices on Beijing's economy are analyzed using input-output tables.The carbon price costs are levied in accordance with the products'embodied carbon emission.By calculation,given the carbon price rate of 10 RMB/t-CO_2,the total carbon costs of Beijing account for approximately 0.22-0.40%of its gross revenue the same year.Among all industries,construction bears the largest carbon cost Among export sectors,the coal mining and washing industry has much higher export carbon price intensity than other industries.Apart from traditional energy-intensive industries,tertiary industry,which accounts for more than 70%of Beijing's economy,also bears a major carbon cost because of its large economic size.However,from 2007 to 2010,adjustment of the investment structure has reduced the emission intensity in investment sectors,contributing to the reduction of overall emissions and carbon price intensity.展开更多
Soil organic carbon （SOC）, soil microbial biomass carbon （SMBC） and SMBC quotient （SMBC/SOC, qSMBC） are key indexes of soil biological fertility because of the relationship to soil nutrition supply capacity. Yet...Soil organic carbon （SOC）, soil microbial biomass carbon （SMBC） and SMBC quotient （SMBC/SOC, qSMBC） are key indexes of soil biological fertility because of the relationship to soil nutrition supply capacity. Yet it remains unknown how these three indexes change, which limits our understanding about how soil respond to different fertilization practices. Based on a 22-yr （1990-2011） long-term fertilization experiment in northwest China, we investigated the dynamics of SMBC and qSMBC during the growing period of winter wheat, the relationships between the SMBC, qSMBC, soil organic carbon （SOC） concentrations, the carbon input and grain yield of wheat as well. Fertilization treatments were 1） nonfertilization （control）; 2） chemical nitrogen plus phosphate plus potassium （NPK）; 3） NPK plus animal manure （NPKM）; 4） double NPKM （hNPKM） and 5） NPK plus straw （NPKS）. Results showed that the SMBC and qSMBC were significantly different among returning, jointing, flowering and harvest stages of wheat under long-term fertilization. And the largest values were observed in the flowering stage. Values for SMBC and qSMBC ranged from 37.5 to 106.0 mg kg1 and 0.41 to 0.61%, respectively. The mean value rank of SMBC during the whole growing period of wheat was hNPKM〉NPK_M〉NPKS〉CK〉NPK. But there were no statistically significant differences between hNPKM and NPKM, or between CK and NPK. The order for qSMBC was NPKS〉NPKM〉CK〉hNPKM〉NPK. These results indicated that NPKS significantly increased the ratio of SMBC to SOC, i.e., qSMBC, compared with NPK fertilizer or other two NPKM fertilizations. Significant linear relationships were observed between the annual carbon input and SOC （P〈0.01） or SMBC （P〈0.05）, and between the relative grain yield of wheat and the SOC content as well （P〈0.05）. But the qSMBC was not correlated with the annual carbon input. It is thus obvious that the combination of manure, straw with mineral fertilizer may be benefit to increase SOC and improve soil quality than using only mineral fertilizer.展开更多
以湖北省恩施州烟区为例,通过生产调研与数据统计,对烤烟不同生产阶段(育苗期、大田生长期和采后烘烤期)以及整个生产过程的间接碳排放量进行了核算。结果表明:烤烟生产过程中主要碳源的碳排放量表现为烘烤能源>电力>农膜和肥料&...以湖北省恩施州烟区为例,通过生产调研与数据统计,对烤烟不同生产阶段(育苗期、大田生长期和采后烘烤期)以及整个生产过程的间接碳排放量进行了核算。结果表明:烤烟生产过程中主要碳源的碳排放量表现为烘烤能源>电力>农膜和肥料>农药、机械油耗和人工;采后烘烤期的碳排放量最大,大田生长期的次之,育苗期的最小;在大田生长期,不同肥力和不同种植规模烟田的碳排放总量有所差异,其中由肥料产生的碳排放量占总碳排放量的比例最大;按照烤房类型划分,烤烟整个生产过程的间接碳排放量表现为燃煤型烤房(5167.80 kg C/hm^(2))>生物质能源型烤房(2256.75 kg C/hm^(2))。恩施州烤烟生产中间接碳排放的主要影响因素为烘烤能源、电力,其次为农膜和肥料。因此,用生物质燃料全面替代煤炭作为烘烤能源是烤烟生产减少碳排放的重要途径。展开更多
基金supported by the National Key Research and Development Program(Grant No.2021YFE0114500)the Strategic Priority Research Program of the Chinese Academy of Sciences(Grant No.XDA26010103)the Major Program for Basic Research Project of Yunnan Province(Grant No.202101BC070002)。
文摘Plant root-derived carbon(C)inputs(I_(root))are the primary source of C in mineral bulk soil.However,a fraction of I_(root)may lose quickly(I_(loss),e.g.,via rhizosphere microbial respiration,leaching and fauna feeding)without contributing to long-term bulk soil C storage,yet this loss has never been quantified,particularly on a global scale.In this study we integrated three observational global data sets including soil radiocarbon content,allocation of photo synthetically assimilated C,and root biomass distribution in 2,034 soil profiles to quantify I_(root)and its contribution to the bulk soil C pool.We show that global average I_(root)in the 0-200 cm soil profile is 3.5 Mg ha^(-1)yr^(-1),~80%of which(i.e.,I_(loss))is lost rather than co ntributing to long-term bulk soil C storage.I_(root)decreases exponentially with soil depth,and the top 20 cm soil contains>60%of total I_(root).Actual C input contributing to long-term bulk soil storage(i.e.,I_(root)-I_(loss))shows a similar depth distribution to I_(root).We also map I_(loss)and its depth distribution across the globe.Our results demonstrate the global significance of direct C losses which limit the contribution of I_(root)to bulk soil C storage;and provide spatially explicit data to facilitate reliable soil C predictions via separating direct C losses from total root-derived C inputs.
基金Sol Leshin UCLA-BGU Program,grant number 8721991.
文摘Aims Resource allocation in plants can be strongly affected by competition.Besides plant–plant interactions,terrestrial plants compete with the soil bacterial community over nutrients.Since the bacterial communities cannot synthesize their own energy sources,they are dependent on external carbon sources.Unlike the effect of overall amounts of carbon(added to the soil)on plant performance,the effect of fine scale temporal variation in soil carbon inputs on the bacterial biomass and its cascading effects on plant growth are largely unknown.We hypothesize that continuous carbon supply(small temporal variance)will result in a relatively constant bacterial biomass that will effectively compete with plants for nutrients.On the other hand,carbon pulses(large temporal variance)are expected to cause oscillations in bacterial biomass,enabling plants temporal escape from competition and possibly enabling increased growth.We thus predicted that continuous carbon supply would increase root allocation at the expense of decreased reproductive output.We also expected this effect to be noticeable only when sufficient nutrients were present in the soil.Methods Wheat plants were grown for 64 days in pots containing either sterilized or inoculated soils,with or without slow-release fertilizer,subjected to one of the following six carbon treatments:daily(1.5mg glucose),every other day(3mg glucose),4 days(6mg glucose),8 days(12mg glucose),16 days(24mg glucose)and no carbon control.Important Findings Remarkably,carbon pulses(every 2–16 days)led to increased reproductive allocation at the expense of decreased root allocation in plants growing in inoculated soils.Consistent with our prediction,these effects were noticeable only when sufficient nutrients were present in the soil.Furthermore,soil inoculation in plants subjected to low nutrient availability resulted in decreased total plant biomass.We interpret this to mean that when the amount of available nutrients is low,these nutrients are mainly used by the bacterial community.Our results show that temporal variation in soil carbon inputs may play an important role in aboveground–belowground interactions,affecting plant resource allocation.
基金sponsored by NSFC(Grant No.71073124)National Social Science Fund Key Projects(Grant No.11AZD028)the Central University Basic Scientific Research Funds
文摘Becoming the world's largest emitter of carbon makes China the object of criticism;however,people may ignore the fact that when China exports low-carbon products,the carbon emissions have been left in the meanwhile,forming the so-called"embodied carbon".Using the input-output model,this paper analyzes the carbon emission intensity and amount of embodied carbon of various sectors in China's export trade in 2002 and 2007,and filters out high carbon emission sectors.In addition,this paper also points out the problem of carbon emissions'international transfer from developed countries to China through the analysis of national and regional flow of export carbon emissions and changing of the proportion of emissions for exports relative to total emissions,and explains the reason that caused carbon transfer to China by using the treadmill of production theory.Based on that,this paper proposes some measures for carbon reduction in China from the foreign trade perspective.
基金The authors would like to thank Key Projects in the National Science&Technology Pillar Program during the Twelfth Five Year Plan Period[grant number 2012BAC20B03]Beijing Natural Science Foundation[grant number 9112008]for supporting this research
文摘Under the pressure of sustained growth in energy consumption in China,the implementation of a carbon pricing mechanism is an effective economic policy measure for promoting emission reduction,as well as a hotspot of research among scholars and policy makers.In this paper,the effects of carbon prices on Beijing's economy are analyzed using input-output tables.The carbon price costs are levied in accordance with the products'embodied carbon emission.By calculation,given the carbon price rate of 10 RMB/t-CO_2,the total carbon costs of Beijing account for approximately 0.22-0.40%of its gross revenue the same year.Among all industries,construction bears the largest carbon cost Among export sectors,the coal mining and washing industry has much higher export carbon price intensity than other industries.Apart from traditional energy-intensive industries,tertiary industry,which accounts for more than 70%of Beijing's economy,also bears a major carbon cost because of its large economic size.However,from 2007 to 2010,adjustment of the investment structure has reduced the emission intensity in investment sectors,contributing to the reduction of overall emissions and carbon price intensity.
基金the National Natural Science Foundation of China (41061035, 41371247)the Project of Aid of Science and Technology in Xinjiang, China (201191140) for providing funding for this work
文摘Soil organic carbon （SOC）, soil microbial biomass carbon （SMBC） and SMBC quotient （SMBC/SOC, qSMBC） are key indexes of soil biological fertility because of the relationship to soil nutrition supply capacity. Yet it remains unknown how these three indexes change, which limits our understanding about how soil respond to different fertilization practices. Based on a 22-yr （1990-2011） long-term fertilization experiment in northwest China, we investigated the dynamics of SMBC and qSMBC during the growing period of winter wheat, the relationships between the SMBC, qSMBC, soil organic carbon （SOC） concentrations, the carbon input and grain yield of wheat as well. Fertilization treatments were 1） nonfertilization （control）; 2） chemical nitrogen plus phosphate plus potassium （NPK）; 3） NPK plus animal manure （NPKM）; 4） double NPKM （hNPKM） and 5） NPK plus straw （NPKS）. Results showed that the SMBC and qSMBC were significantly different among returning, jointing, flowering and harvest stages of wheat under long-term fertilization. And the largest values were observed in the flowering stage. Values for SMBC and qSMBC ranged from 37.5 to 106.0 mg kg1 and 0.41 to 0.61%, respectively. The mean value rank of SMBC during the whole growing period of wheat was hNPKM〉NPK_M〉NPKS〉CK〉NPK. But there were no statistically significant differences between hNPKM and NPKM, or between CK and NPK. The order for qSMBC was NPKS〉NPKM〉CK〉hNPKM〉NPK. These results indicated that NPKS significantly increased the ratio of SMBC to SOC, i.e., qSMBC, compared with NPK fertilizer or other two NPKM fertilizations. Significant linear relationships were observed between the annual carbon input and SOC （P〈0.01） or SMBC （P〈0.05）, and between the relative grain yield of wheat and the SOC content as well （P〈0.05）. But the qSMBC was not correlated with the annual carbon input. It is thus obvious that the combination of manure, straw with mineral fertilizer may be benefit to increase SOC and improve soil quality than using only mineral fertilizer.
文摘以湖北省恩施州烟区为例,通过生产调研与数据统计,对烤烟不同生产阶段(育苗期、大田生长期和采后烘烤期)以及整个生产过程的间接碳排放量进行了核算。结果表明:烤烟生产过程中主要碳源的碳排放量表现为烘烤能源>电力>农膜和肥料>农药、机械油耗和人工;采后烘烤期的碳排放量最大,大田生长期的次之,育苗期的最小;在大田生长期,不同肥力和不同种植规模烟田的碳排放总量有所差异,其中由肥料产生的碳排放量占总碳排放量的比例最大;按照烤房类型划分,烤烟整个生产过程的间接碳排放量表现为燃煤型烤房(5167.80 kg C/hm^(2))>生物质能源型烤房(2256.75 kg C/hm^(2))。恩施州烤烟生产中间接碳排放的主要影响因素为烘烤能源、电力,其次为农膜和肥料。因此,用生物质燃料全面替代煤炭作为烘烤能源是烤烟生产减少碳排放的重要途径。
