Owing to the harsh natural environment and unsustainable production system,environmental vulnerability differs substantially among and within regions^([1]).Over the past 20 years,the most environmentally vulnerable co...Owing to the harsh natural environment and unsustainable production system,environmental vulnerability differs substantially among and within regions^([1]).Over the past 20 years,the most environmentally vulnerable countries lost over half of their economic growth potential^([2]).International trade is a double-edged sword for environmental vulnerability.On the one hand,production occurs beyond countries’borders while associated environmental impacts are displaced away from the location of consumption.展开更多
Aims The balance between leaf photosynthesis and respiration of terrestrial plants determines the net carbon(C)gain by vegetation and consequently is important to climate–C cycle feedback.This study is to reveal the ...Aims The balance between leaf photosynthesis and respiration of terrestrial plants determines the net carbon(C)gain by vegetation and consequently is important to climate–C cycle feedback.This study is to reveal the global patterns of the responses of leaf-level net photosynthesis and dark respiration to elevated temperature.Methods Data for leaf-level net photosynthesis rate(P_(n))and dark respiration rate(R_(d))in natural terrestrial plant species with standard deviation(or standard error or confidence interval)and sample size were collected from searched literatures on Web of Science.Then a metaanalysis was conducted to estimate the effects of experimental warming on leaf-level P_(n) and R_(d) of terrestrial plants.Important findings Across all the plants included in the analysis,warming enhanced P_(n) and R_(d) significantly by 6.13 and 33.14%,respectively.However,the responses were plant functional type(PFT)specific.Specifically,photosynthesis of C_(4) herbs responded to experimental warming positively but that of C_(3) herbs did not,whereas their respiratory responses were similar,suggesting C_(4) plants would benefit more from warming.The photosynthetic response declined linearly with increasing ambient temperature.The respiratory responses linearly enhanced with the increase in warming magnitude.In addition,a thermal acclimation of R_(d),instead of P_(n),was observed.Although greater proportion of fixed C was consumed(greater R_(d)/P_(n) ratio),warming significantly enhanced the daily net C balance at the leaf level.This provides an important mechanism for the positive responses of plant biomass and net primary productivity to warming.Overall,the findings,including the contrastive responses of different PFTs and the enhancement in daily leaf net C balance,are important for improving model projection of the climate–C cycle feedback.展开更多
The priming effect (PE) plays a critical role in the control of soil carbon (C) cycling and influences the alteration of soil organic C (SOC) decomposition by fresh C input.However,drivers of PE for the fast and slow ...The priming effect (PE) plays a critical role in the control of soil carbon (C) cycling and influences the alteration of soil organic C (SOC) decomposition by fresh C input.However,drivers of PE for the fast and slow SOC pools remain unclear because of the varying results from individual studies.Using meta-analysis in combination with boosted regression tree (BRT) analysis,we evaluated the relative contribution of multiple drivers of PE with substrate and their patterns across each driver gradient.The results showed that the variability of PE was larger for the fast SOC pool than for the slow SOC pool.Based on the BRT analysis,67%and 34%of the variation in PE were explained for the fast and slow SOC pools,respectively.There were seven determinants of PE for the fast SOC pool,with soil total nitrogen (N) content being the most important,followed by,in a descending order,substrate C:N ratio,soil moisture,soil clay content,soil pH,substrate addition rate,and SOC content.The directions of PE were negative when soil total N content and substrate C:N ratio were below 2 g kg~(-1)and 20,respectively,but the directions changed from negative to positive with increasing levels of this two factors.Soils with optimal water content (50%–70%of the water-holding capacity) or moderately low pH (5–6) were prone to producing a greater PE.For the slow SOC pool,soil p H and soil total N content substantially explained the variation in PE.The magnitude of PE was likely to decrease with increasing soil pH for the slow SOC pool.In addition,the magnitude of PE slightly fluctuated with soil N content for the slow SOC pool.Overall,this meta-analysis provided new insights into the distinctive PEs for different SOC pools and indicated knowledge gaps between PE and its regulating factors for the slow SOC pool.展开更多
Background:Countries have long been making efforts by reducing greenhouse-gas emissions to mitigate climate change.In the agreements of the United Nations Framework Convention on Climate Change,involved countries have...Background:Countries have long been making efforts by reducing greenhouse-gas emissions to mitigate climate change.In the agreements of the United Nations Framework Convention on Climate Change,involved countries have committed to reduction targets.However,carbon(C)sink and its involving processes by natural ecosystems remain difficult to quantify.Methods:Using a transient traceability framework,we estimated country-level land C sink and its causing components by 2050 simulated by 12 Earth System Models involved in the Coupled Model Intercomparison Project Phase 5(CMIP5)under RCP8.5.Results:The top 20 countries with highest C sink have the potential to sequester 62 Pg C in total,among which,Russia,Canada,USA,China,and Brazil sequester the most.This C sink consists of four components:productiondriven change,turnover-driven change,change in instantaneous C storage potential,and interaction between production-driven change and turnover-driven change.The four components account for 49.5%,28.1%,14.5%,and 7.9%of the land C sink,respectively.Conclusion:The model-based estimates highlight that land C sink potentially offsets a substantial proportion of greenhouse-gas emissions,especially for countries where net primary production(NPP)likely increases substantially and inherent residence time elongates.展开更多
A commentary on our recent article on Journal of Plant Ecology(Liang et al.2013)by Smith(2014)argues that it is not appro-priate to lump data from different experiments together to demonstrate the thermal acclimation ...A commentary on our recent article on Journal of Plant Ecology(Liang et al.2013)by Smith(2014)argues that it is not appro-priate to lump data from different experiments together to demonstrate the thermal acclimation of leaf dark respiration.We agree that many factors,as listed by Smith(2014),would impact the responses of leaf carbon exchanges to warming and the consequent thermal acclimation.Although not all factors were included,we discussed in the article that light and vapor pressure deficit(VPD)could have affected our conclusions(Liang et al.2013).The“acclimation”in our paper did not exactly accord with the physiological definition(Atkin and Tjoelker 2003;Smith and Dukes 2013).It is hard to make the environ-mental factors as well as warming magnitude coherent in a syn-thesis study because the data were from different experiments.Therefore,the“acclimation”in our meta-analysis was more like an apparent one rather than the physiologically intrinsic one as defined by Atkin et al.展开更多
基金supported by the Third Xinjiang Scientific Expedition Program(2021xjkk0904)the National Natural Science Foundation of China(42371207,42225107).
文摘Owing to the harsh natural environment and unsustainable production system,environmental vulnerability differs substantially among and within regions^([1]).Over the past 20 years,the most environmentally vulnerable countries lost over half of their economic growth potential^([2]).International trade is a double-edged sword for environmental vulnerability.On the one hand,production occurs beyond countries’borders while associated environmental impacts are displaced away from the location of consumption.
基金supported by the National Natural Science Foundation of China(32192462,32192460)the Chinese Universities Scientific Fund(2020RC009)the 2115 Talent Development Program of China Agricultural University(1201-00109017).
基金National Natural Science Foundation of China(41030104/D0308,30925009)the Ministry of Science and Technology of China(2013CB956300).
文摘Aims The balance between leaf photosynthesis and respiration of terrestrial plants determines the net carbon(C)gain by vegetation and consequently is important to climate–C cycle feedback.This study is to reveal the global patterns of the responses of leaf-level net photosynthesis and dark respiration to elevated temperature.Methods Data for leaf-level net photosynthesis rate(P_(n))and dark respiration rate(R_(d))in natural terrestrial plant species with standard deviation(or standard error or confidence interval)and sample size were collected from searched literatures on Web of Science.Then a metaanalysis was conducted to estimate the effects of experimental warming on leaf-level P_(n) and R_(d) of terrestrial plants.Important findings Across all the plants included in the analysis,warming enhanced P_(n) and R_(d) significantly by 6.13 and 33.14%,respectively.However,the responses were plant functional type(PFT)specific.Specifically,photosynthesis of C_(4) herbs responded to experimental warming positively but that of C_(3) herbs did not,whereas their respiratory responses were similar,suggesting C_(4) plants would benefit more from warming.The photosynthetic response declined linearly with increasing ambient temperature.The respiratory responses linearly enhanced with the increase in warming magnitude.In addition,a thermal acclimation of R_(d),instead of P_(n),was observed.Although greater proportion of fixed C was consumed(greater R_(d)/P_(n) ratio),warming significantly enhanced the daily net C balance at the leaf level.This provides an important mechanism for the positive responses of plant biomass and net primary productivity to warming.Overall,the findings,including the contrastive responses of different PFTs and the enhancement in daily leaf net C balance,are important for improving model projection of the climate–C cycle feedback.
文摘The priming effect (PE) plays a critical role in the control of soil carbon (C) cycling and influences the alteration of soil organic C (SOC) decomposition by fresh C input.However,drivers of PE for the fast and slow SOC pools remain unclear because of the varying results from individual studies.Using meta-analysis in combination with boosted regression tree (BRT) analysis,we evaluated the relative contribution of multiple drivers of PE with substrate and their patterns across each driver gradient.The results showed that the variability of PE was larger for the fast SOC pool than for the slow SOC pool.Based on the BRT analysis,67%and 34%of the variation in PE were explained for the fast and slow SOC pools,respectively.There were seven determinants of PE for the fast SOC pool,with soil total nitrogen (N) content being the most important,followed by,in a descending order,substrate C:N ratio,soil moisture,soil clay content,soil pH,substrate addition rate,and SOC content.The directions of PE were negative when soil total N content and substrate C:N ratio were below 2 g kg~(-1)and 20,respectively,but the directions changed from negative to positive with increasing levels of this two factors.Soils with optimal water content (50%–70%of the water-holding capacity) or moderately low pH (5–6) were prone to producing a greater PE.For the slow SOC pool,soil p H and soil total N content substantially explained the variation in PE.The magnitude of PE was likely to decrease with increasing soil pH for the slow SOC pool.In addition,the magnitude of PE slightly fluctuated with soil N content for the slow SOC pool.Overall,this meta-analysis provided new insights into the distinctive PEs for different SOC pools and indicated knowledge gaps between PE and its regulating factors for the slow SOC pool.
基金supported by the National Science Foundation Grants(DEB,1655499,2017884)US Department of Energy(DE-SC0020227)the subcontracts 4000158404 and 4000161830 from Oak Ridge National Laboratory(ORNL)to the Northern Arizona University。
文摘Background:Countries have long been making efforts by reducing greenhouse-gas emissions to mitigate climate change.In the agreements of the United Nations Framework Convention on Climate Change,involved countries have committed to reduction targets.However,carbon(C)sink and its involving processes by natural ecosystems remain difficult to quantify.Methods:Using a transient traceability framework,we estimated country-level land C sink and its causing components by 2050 simulated by 12 Earth System Models involved in the Coupled Model Intercomparison Project Phase 5(CMIP5)under RCP8.5.Results:The top 20 countries with highest C sink have the potential to sequester 62 Pg C in total,among which,Russia,Canada,USA,China,and Brazil sequester the most.This C sink consists of four components:productiondriven change,turnover-driven change,change in instantaneous C storage potential,and interaction between production-driven change and turnover-driven change.The four components account for 49.5%,28.1%,14.5%,and 7.9%of the land C sink,respectively.Conclusion:The model-based estimates highlight that land C sink potentially offsets a substantial proportion of greenhouse-gas emissions,especially for countries where net primary production(NPP)likely increases substantially and inherent residence time elongates.
文摘A commentary on our recent article on Journal of Plant Ecology(Liang et al.2013)by Smith(2014)argues that it is not appro-priate to lump data from different experiments together to demonstrate the thermal acclimation of leaf dark respiration.We agree that many factors,as listed by Smith(2014),would impact the responses of leaf carbon exchanges to warming and the consequent thermal acclimation.Although not all factors were included,we discussed in the article that light and vapor pressure deficit(VPD)could have affected our conclusions(Liang et al.2013).The“acclimation”in our paper did not exactly accord with the physiological definition(Atkin and Tjoelker 2003;Smith and Dukes 2013).It is hard to make the environ-mental factors as well as warming magnitude coherent in a syn-thesis study because the data were from different experiments.Therefore,the“acclimation”in our meta-analysis was more like an apparent one rather than the physiologically intrinsic one as defined by Atkin et al.