To clarify the characteristics of photoinhibition and the primary defense mechanisms of ephemeral plant leaves against photodestruction under high temperature stress,inhibitors and the technology to determine chloroph...To clarify the characteristics of photoinhibition and the primary defense mechanisms of ephemeral plant leaves against photodestruction under high temperature stress,inhibitors and the technology to determine chlorophyll fluorescence were used to explore the protective effects of D1 protein turnover and the lutein cycle in the high temperature stress of the leaves of three ephemeral plants.The results showed that the maximum light conversion efficiency(Fv/Fm)of the ephemeral plant leaves decreased,and the initial fluorescence(Fo)increased under 35℃±1℃ heat stress for 1-4 h or on sunny days in the summer.Both Fv/Fm and Fo could be recovered after 8 h of darkness or afternoon weakening of the external temperature.Streptomycin sulfate(SM)or dithiothreitol(DTT)accelerated the decrease of Fv/Fm and the photochemical quenching coefficient(qP)in the leaves of three ephemeral plants at high temperature,and the decrease was greater in the SM than in the DTT treatment.When the high temperature stress was prolonged,the Y(II)values of light energy distribution parameters of PSII decreased,and the Y(NPQ)and Y(NO)values increased gradually in all the treatment groups of the three ephemeral plants.The results showed that the leaves of the three ephemeral plants had their own highly advanced mechanisms to protect against photodamage,which inhibited the turnover of D1 protein and xanthophyll cycle.This can damage the PSII reaction center in the leaves of the three ephemeral plants under high temperature.The protective effect of D1 protein turnover on heat stress in Erodium oxyrrhynchum and Senecio subdentatus was greater than that of the lutein cycle,while the protective effect of lutein cycle was greater than that of D1 protein turnover in Heliotropium acutiflorum subjected to heat damage.展开更多
Lakes play a crucial role in the carbon exchange of inland waters.However,determining the factors influencing carbon dioxide fluxes(FCO_(2)) from lakes remains challenging.Here,we synthesize 332 months of eddy covaria...Lakes play a crucial role in the carbon exchange of inland waters.However,determining the factors influencing carbon dioxide fluxes(FCO_(2)) from lakes remains challenging.Here,we synthesize 332 months of eddy covariance measurements from 19 lakes and 8 reservoirs(collectively referred to as lakes) to identify the dominant environmental factors of FCO_(2) across multiple timescales and to explore the carbon dioxide(CO_(2)) exchange mechanisms among different lake types.We found that increasing lake p H enhances the likelihood of the system acting as a carbon sink.The dominant factors influencing FCO_(2) differ markedly across timescales:radiation-related factors at the diel scale,energy exchange-related factors at the multi-day scale,and temperaturerelated factors at the seasonal scale.Relative mutual information results further reveal that the lags of these dominant factors vary among lake types.For the dominant factor on the diel scale,the lags of shortwave radiation incoming in acidic,neutral,and alkaline lakes are-0.3±0.5 days,0.4±0.9 days,and 0.2 ±0.7 days,respectively.The multi-day scale dominant factor,sensible heat,also has the shortest lags in acidic lakes.Seasonally,the lags of temperatures are more variable,indicating the influence of dominant factors on FCO_(2) and the lagged relationships are more diverse and complex on longer time scales.Our study highlights the importance of multi-site synthesis when extrapolating and generalizing scales across lake types.Understanding the drivers and mechanisms for lake FCO_(2) can help improve future simulations and the accurate estimation of lake carbon budgets.展开更多
Knowledge of forest management types is key to sustainable forest restoration practices,forest biomass assessment,and carbon accounting.However,there are no available global forest-management maps because of the spect...Knowledge of forest management types is key to sustainable forest restoration practices,forest biomass assessment,and carbon accounting.However,there are no available global forest-management maps because of the spectral similarity of different forest management types.As such,we applied random forest and change detection algorithms to generate annual maps of 6 forest management types at a spatial resolution of 250 m from 2001 to 2020 including naturally regenerated forest(unmanaged and managed),planted forest(rotation of>15 years and≤15 years),oil palm plantation,and agroforestry.In general,validation results on a point scale show that the overall accuracy is 86.82%±9.14%,indicating that our annual maps accurately represent global spatiotemporal variations in forest management types.Furthermore,we estimated the annual biomass carbon stock of different forest management types.The net expanded areas of planted forest,oil palm plantation,and agroforestry offset 59.56%of the loss of forest area and 77.13%of the loss of biomass carbon stock due to the decrease in the naturally regenerated forest.The decrease of managed natural regeneration forests,the expansion of planted forests with a rotation period of more than 15 years,and agroforestry resulted from reforestation practices,while the expansion of planted forests with a rotation period of less than 15 years and oil palm plantations resulted from the removal of part of agroforestry.Moreover,the expansion of planted forests with a rotation of less than 15 years(72.73%)dominates the global expansion of planted forests,and China has contributed 42.20%of this expansion.Our results are beneficial for nature solution-based climate change mitigation.展开更多
基金This work was supported by the Open Foundation of the State Key Laboratory of Desert and Oasis Ecology(KH0054).
文摘To clarify the characteristics of photoinhibition and the primary defense mechanisms of ephemeral plant leaves against photodestruction under high temperature stress,inhibitors and the technology to determine chlorophyll fluorescence were used to explore the protective effects of D1 protein turnover and the lutein cycle in the high temperature stress of the leaves of three ephemeral plants.The results showed that the maximum light conversion efficiency(Fv/Fm)of the ephemeral plant leaves decreased,and the initial fluorescence(Fo)increased under 35℃±1℃ heat stress for 1-4 h or on sunny days in the summer.Both Fv/Fm and Fo could be recovered after 8 h of darkness or afternoon weakening of the external temperature.Streptomycin sulfate(SM)or dithiothreitol(DTT)accelerated the decrease of Fv/Fm and the photochemical quenching coefficient(qP)in the leaves of three ephemeral plants at high temperature,and the decrease was greater in the SM than in the DTT treatment.When the high temperature stress was prolonged,the Y(II)values of light energy distribution parameters of PSII decreased,and the Y(NPQ)and Y(NO)values increased gradually in all the treatment groups of the three ephemeral plants.The results showed that the leaves of the three ephemeral plants had their own highly advanced mechanisms to protect against photodamage,which inhibited the turnover of D1 protein and xanthophyll cycle.This can damage the PSII reaction center in the leaves of the three ephemeral plants under high temperature.The protective effect of D1 protein turnover on heat stress in Erodium oxyrrhynchum and Senecio subdentatus was greater than that of the lutein cycle,while the protective effect of lutein cycle was greater than that of D1 protein turnover in Heliotropium acutiflorum subjected to heat damage.
基金supported by the National Natural Science Foundation of China(Grant No.42361144877)the Tianshan Talent Training Program of Xinjiang Uygur Autonomous Region,China(Grant No.2023TSYCJU0005)+4 种基金the Third Xinjiang Scientific Expedition Program(Grant No.2022xjkk0106)the U.S.National Science Foundation(NSF) North Temperate Lakes Long-Term Ecological Research(LTER) program under Cooperative Agreement(Grant No.DEB-2025982)the Ministry of Education of Singapore(Grant No.A-8001793-00-00)the German Science Foundation(DFG) within the projects Trega Ta(Grant No.288267759)MEDIWA(Grant No.445326344)。
文摘Lakes play a crucial role in the carbon exchange of inland waters.However,determining the factors influencing carbon dioxide fluxes(FCO_(2)) from lakes remains challenging.Here,we synthesize 332 months of eddy covariance measurements from 19 lakes and 8 reservoirs(collectively referred to as lakes) to identify the dominant environmental factors of FCO_(2) across multiple timescales and to explore the carbon dioxide(CO_(2)) exchange mechanisms among different lake types.We found that increasing lake p H enhances the likelihood of the system acting as a carbon sink.The dominant factors influencing FCO_(2) differ markedly across timescales:radiation-related factors at the diel scale,energy exchange-related factors at the multi-day scale,and temperaturerelated factors at the seasonal scale.Relative mutual information results further reveal that the lags of these dominant factors vary among lake types.For the dominant factor on the diel scale,the lags of shortwave radiation incoming in acidic,neutral,and alkaline lakes are-0.3±0.5 days,0.4±0.9 days,and 0.2 ±0.7 days,respectively.The multi-day scale dominant factor,sensible heat,also has the shortest lags in acidic lakes.Seasonally,the lags of temperatures are more variable,indicating the influence of dominant factors on FCO_(2) and the lagged relationships are more diverse and complex on longer time scales.Our study highlights the importance of multi-site synthesis when extrapolating and generalizing scales across lake types.Understanding the drivers and mechanisms for lake FCO_(2) can help improve future simulations and the accurate estimation of lake carbon budgets.
基金supported by the BNU-FGS Global Environmental Change Program(grant 2023-GC-ZYTS-01)the High-Resolution Earth Observation Major Special Aerial Observation System(grant 30-H30C01-9004-19/21)the State Key Laboratory of Earth Surface Processes and Resource Ecology(grant 2023-KF-02).
文摘Knowledge of forest management types is key to sustainable forest restoration practices,forest biomass assessment,and carbon accounting.However,there are no available global forest-management maps because of the spectral similarity of different forest management types.As such,we applied random forest and change detection algorithms to generate annual maps of 6 forest management types at a spatial resolution of 250 m from 2001 to 2020 including naturally regenerated forest(unmanaged and managed),planted forest(rotation of>15 years and≤15 years),oil palm plantation,and agroforestry.In general,validation results on a point scale show that the overall accuracy is 86.82%±9.14%,indicating that our annual maps accurately represent global spatiotemporal variations in forest management types.Furthermore,we estimated the annual biomass carbon stock of different forest management types.The net expanded areas of planted forest,oil palm plantation,and agroforestry offset 59.56%of the loss of forest area and 77.13%of the loss of biomass carbon stock due to the decrease in the naturally regenerated forest.The decrease of managed natural regeneration forests,the expansion of planted forests with a rotation period of more than 15 years,and agroforestry resulted from reforestation practices,while the expansion of planted forests with a rotation period of less than 15 years and oil palm plantations resulted from the removal of part of agroforestry.Moreover,the expansion of planted forests with a rotation of less than 15 years(72.73%)dominates the global expansion of planted forests,and China has contributed 42.20%of this expansion.Our results are beneficial for nature solution-based climate change mitigation.
