Understanding the drivers of variations in fine root lifespan is key to informing nutrient cycling and productivity in terrestrial ecosystems.However,the general patterns and determinants of forest fine root lifespan ...Understanding the drivers of variations in fine root lifespan is key to informing nutrient cycling and productivity in terrestrial ecosystems.However,the general patterns and determinants of forest fine root lifespan at the global scale are still limited.We compiled a dataset of 421 fine root lifespan observations from 76 tree species globally to assess phylogenetic signals among species,explored relationships between fine root lifespan and biotic and abiotic factors,and quantified the relative importance of phylogeny,root system structure and functions,climatic and edaphic factors in driving global fine root lifespan variations.Overall,fine root lifespan showed a clear phylogenetic signal,with gymnosperms having a longer fine root lifespan than angiosperms.Fine root lifespan was longer for evergreens than deciduous trees.Ectomycorrhizal(ECM)plants had an extended fine root lifespan than arbuscular mycorrhizal(AM)plants.Among different climatic zones,fine root lifespan was the longest in the boreal zone,while it did not vary between the temperate and tropical zone.Fine root lifespan increased with soil depth and root order.Furthermore,the analysis of relative importance indicated that phylogeny was the strongest driver influencing the variation in forest fine root lifespan,followed by soil clay content,root order,mean annual temperature,and soil depth,while other environmental factors and root traits exerted weaker effects.Our results suggest that the global pattern of fine root lifespan in forests is shaped by the interplay of phylogeny,root traits and environmental factors.These findings necessitate accurate representations of tree evolutionary history in earth system models to predict fine root longevity and its responses to global changes.展开更多
Global occurrences of Steptoean Positive Carbon Isotope Excursion（SPICE） during Late Cambrian recorded a significant perturbation in marine carbon cycle, and might have had profound impacts on the biological evoluti...Global occurrences of Steptoean Positive Carbon Isotope Excursion（SPICE） during Late Cambrian recorded a significant perturbation in marine carbon cycle, and might have had profound impacts on the biological evolution. In previous studies, SPICE has been reported from the Jiangnan slope belt in South China. To evaluate the bathymetric extent of SPICE, we investigate the limestone samples from the upper Qingxi Formation in the Shaijiang Section in the Jiangnan Basin. Our results show the positive excursions for both carbonate carbon（δ^（13）C） and organic carbon（δ^（13）C_（org）） isotopes, as well as the concurrent positive shifts in sulfur isotopes of carbonate associated sulfate（CAS, δ^（34）S_（CAS）） and pyrite（δ^（34）S_（pyrite））, unequivocally indicating the presence of SPICE in the Jiangnan Basin. A 4‰ increase in δ^（13）C_（carb） of the Qingxi limestone implies the increase of the relative flux of organic carbon burial by a factor of two. Concurrent positive excursions in δ^（34）S_（CAS） and δ^（34）S_（pyrite） have been attributed to the enhanced pyrite burial in oceans with extremely low concentration and spatially heterogeneous isotopic composition of seawater sulfate. Here, we propose that the seawater sulfur isotopic heterogeneity can be generated by volatile organic sulfur compound（VOSC, such as methanethiol and dimethyl sulfide） formation in sulfidic continental margins that were widespread during SPICE. Emission of 32S-enriched VOSC in atmosphere, followed by lateral transportation and aerobic oxidation in atmosphere, and precipitation in open oceans result in a net flux of ^（32）S from continental margins to open oceans, elevating δ^（34）S of seawater sulfate in continental margins. A simple box model indicates that about 35% to 75% of seawater sulfate in continental margins needs to be transported to open oceans via VOSC formation.展开更多
The effect of evolutionary history on wood density variation may play an important role in shaping variation in wood density,but this has largely not been tested.Using a comprehensive global dataset including 27,297 m...The effect of evolutionary history on wood density variation may play an important role in shaping variation in wood density,but this has largely not been tested.Using a comprehensive global dataset including 27,297 measurements of wood density from 2621 tree species worldwide,we test the hypothesis that the legacy of evolutionary history plays an important role in driving the variation of wood density among tree species.We assessed phylogenetic signal in different taxonomic(e.g.,angiosperms and gymnosperms)and ecological(e.g.,tropical,temperate,and boreal)groups of tree species,explored the biogeographical and phylogenetic patterns of wood density,and quantified the relative importance of current environmental factors(e.g.,climatic and soil variables)and evolutionary history(i.e.,phylogenetic relatedness among species and lineages)in driving global wood density variation.We found that wood density displayed a significant phylogenetic signal.Wood density differed among different biomes and climatic zones,with higher mean values of wood density in relatively drier regions(highest in subtropical desert).Our study revealed that at a global scale,for angiosperms and gymnosperms combined,phylogeny and species(representing the variance explained by taxonomy and not direct explained by long-term evolution process)explained 84.3%and 7.7%of total wood density variation,respectively,whereas current environment explained 2.7%of total wood density variation when phylogeny and species were taken into account.When angiosperms and gymnosperms were considered separately,the three proportions of explained variation are,respectively,84.2%,7.5%and 6.7%for angiosperms,and 45.7%,21.3%and 18.6%for gymnosperms.Our study shows that evolutionary history outpaced current environmental factors in shaping global variation in wood density.展开更多
Continental silicate weathering acts as a crucial negative feedback mechanism for removing atmospheric CO_(2) and maintaining Earth's long-term climate stability.However,quantifying continental silicate weathering...Continental silicate weathering acts as a crucial negative feedback mechanism for removing atmospheric CO_(2) and maintaining Earth's long-term climate stability.However,quantifying continental silicate weathering rates and fluxes continues to pose a fundamental challenge in Earth system science.This study utilizes the GEOCLIM carbon cycle model,which integrates modern high-resolution(0.1°×0.1°)datasets on surface temperature,runoff,topography,and lithology to model the spatial distribution of global silicate weathering fluxes.Results indicate a strong correlation between modeled basin-scale outputs and hydrological observations,with weathering rates falling within consistent error margins.Silicate weathering fluxes exhibit distinct latitudinal patterns,with the highest values concentrated within 30°of the equator,accounting for 76.9%of the global total.Continental contributions differ significantly,with Asian river basins representing 36.9%of global fluxes,primarily from Southeast Asia(17.4%),South Asia(8.2%),and East Asia(6.6%).They are followed by South America(29.2%)and Africa(21.7%).Tectonically active regions contribute 21.9%of global silicate weathering,while stable regions account for 72.6%.Multivariate regression analyses using RF and XGBoost machine learning algorithms identify runoff as the primary controlling factor of weathering on a global scale.Weathering in stable regions is jointly regulated by runoff and erosion rates,whereas temperature is the prevailing factor in tectonically active zones.The GEOCLIM model offers a robust framework for quantifying continental weathering processes.Future studies should incorporate organic carbon oxidation,burial,and sulfide oxidation dynamics to clarify carbon cycle interactions and reveal climate-dependent mechanisms for weathering responses and feedback.展开更多
The Cryogenian Sturtian(717–660 Ma)and Marinoan glacial deposits(∼650–635 Ma),typically consisting of alternating layers of glaciogenic diamictite and clast-free lithofacies,indicate dynamic glaciers or glacial-int...The Cryogenian Sturtian(717–660 Ma)and Marinoan glacial deposits(∼650–635 Ma),typically consisting of alternating layers of glaciogenic diamictite and clast-free lithofacies,indicate dynamic glaciers or glacial-interglacial cycles during the global glaciations.This may result from ice sublimation in tropics under a Snowball Earth condition.However,this model fails to explain the deposition patterns observed in mid-latitude continents.We propose the presence of unfrozen oceans while the continents are covered,i.e.,the icy-continents.The open-ocean condition requires low atmospheric pCO_(2)level.We argued that the mantle CO_(2)degassing could be counterbalanced by a growing pool of dissolved organic carbon(DOC)in the deep ocean,maintaining a small marine dissolved inorganic carbon(DIC)pool and a low atmospheric pCO_(2)level.The persistent marine productivity in the open ocean would support the expanded DOC pool due to reduced ocean ventilation and limited terrestrial inputs of oxidants.However,the global glaciation with open oceans was climatically unstable.The fluctuation of the DOC pool on a local or regional scale likely contributed to the frequent glacial-interglacial oscillations recorded in the rock records.Additionally,the expansion of the DOC pool removed seawater nutrients,e.g.,phosphorus(P),and insufficient nutrient supply prevented the transfer of mantle-degassing carbon as DOC,ultimately leading to the termination of global glaciation.The turnover of the DOC pool,caused by deep ocean ventilation in the deglacial period,significantly increased the atmospheric pCO_(2)level.This event was followed by intense continental weathering,increased seawater pH,recovery of primary productivity,cap carbonate precipitation,and eventually,the emergence of new life forms and innovations in the biosphere.展开更多
基金provided by the National Key R&D Program of China(2023YFD2200904)the Scientific Research Project of Anhui Province(2022AH050873)+1 种基金the State Key Laboratory of Subtropical Silviculture(SKLSS-KF2023-08)the Anhui Provincial Science and Technology Special Project(202204c06020014)。
文摘Understanding the drivers of variations in fine root lifespan is key to informing nutrient cycling and productivity in terrestrial ecosystems.However,the general patterns and determinants of forest fine root lifespan at the global scale are still limited.We compiled a dataset of 421 fine root lifespan observations from 76 tree species globally to assess phylogenetic signals among species,explored relationships between fine root lifespan and biotic and abiotic factors,and quantified the relative importance of phylogeny,root system structure and functions,climatic and edaphic factors in driving global fine root lifespan variations.Overall,fine root lifespan showed a clear phylogenetic signal,with gymnosperms having a longer fine root lifespan than angiosperms.Fine root lifespan was longer for evergreens than deciduous trees.Ectomycorrhizal(ECM)plants had an extended fine root lifespan than arbuscular mycorrhizal(AM)plants.Among different climatic zones,fine root lifespan was the longest in the boreal zone,while it did not vary between the temperate and tropical zone.Fine root lifespan increased with soil depth and root order.Furthermore,the analysis of relative importance indicated that phylogeny was the strongest driver influencing the variation in forest fine root lifespan,followed by soil clay content,root order,mean annual temperature,and soil depth,while other environmental factors and root traits exerted weaker effects.Our results suggest that the global pattern of fine root lifespan in forests is shaped by the interplay of phylogeny,root traits and environmental factors.These findings necessitate accurate representations of tree evolutionary history in earth system models to predict fine root longevity and its responses to global changes.
基金supported by the Natural Science Founddation of China (Nos.41272017,41322021)
文摘Global occurrences of Steptoean Positive Carbon Isotope Excursion（SPICE） during Late Cambrian recorded a significant perturbation in marine carbon cycle, and might have had profound impacts on the biological evolution. In previous studies, SPICE has been reported from the Jiangnan slope belt in South China. To evaluate the bathymetric extent of SPICE, we investigate the limestone samples from the upper Qingxi Formation in the Shaijiang Section in the Jiangnan Basin. Our results show the positive excursions for both carbonate carbon（δ^（13）C） and organic carbon（δ^（13）C_（org）） isotopes, as well as the concurrent positive shifts in sulfur isotopes of carbonate associated sulfate（CAS, δ^（34）S_（CAS）） and pyrite（δ^（34）S_（pyrite））, unequivocally indicating the presence of SPICE in the Jiangnan Basin. A 4‰ increase in δ^（13）C_（carb） of the Qingxi limestone implies the increase of the relative flux of organic carbon burial by a factor of two. Concurrent positive excursions in δ^（34）S_（CAS） and δ^（34）S_（pyrite） have been attributed to the enhanced pyrite burial in oceans with extremely low concentration and spatially heterogeneous isotopic composition of seawater sulfate. Here, we propose that the seawater sulfur isotopic heterogeneity can be generated by volatile organic sulfur compound（VOSC, such as methanethiol and dimethyl sulfide） formation in sulfidic continental margins that were widespread during SPICE. Emission of 32S-enriched VOSC in atmosphere, followed by lateral transportation and aerobic oxidation in atmosphere, and precipitation in open oceans result in a net flux of ^（32）S from continental margins to open oceans, elevating δ^（34）S of seawater sulfate in continental margins. A simple box model indicates that about 35% to 75% of seawater sulfate in continental margins needs to be transported to open oceans via VOSC formation.
基金supported by the Scientific Research Project of Anhui Province(2022AH050873)the State Key Laboratory of Subtropical Silviculture(SKLSS-KF2023-08)+1 种基金the Provincial Natural Resources Fund(1908085QC140)the National Key R&D Program of China(2018YFD1000600).
文摘The effect of evolutionary history on wood density variation may play an important role in shaping variation in wood density,but this has largely not been tested.Using a comprehensive global dataset including 27,297 measurements of wood density from 2621 tree species worldwide,we test the hypothesis that the legacy of evolutionary history plays an important role in driving the variation of wood density among tree species.We assessed phylogenetic signal in different taxonomic(e.g.,angiosperms and gymnosperms)and ecological(e.g.,tropical,temperate,and boreal)groups of tree species,explored the biogeographical and phylogenetic patterns of wood density,and quantified the relative importance of current environmental factors(e.g.,climatic and soil variables)and evolutionary history(i.e.,phylogenetic relatedness among species and lineages)in driving global wood density variation.We found that wood density displayed a significant phylogenetic signal.Wood density differed among different biomes and climatic zones,with higher mean values of wood density in relatively drier regions(highest in subtropical desert).Our study revealed that at a global scale,for angiosperms and gymnosperms combined,phylogeny and species(representing the variance explained by taxonomy and not direct explained by long-term evolution process)explained 84.3%and 7.7%of total wood density variation,respectively,whereas current environment explained 2.7%of total wood density variation when phylogeny and species were taken into account.When angiosperms and gymnosperms were considered separately,the three proportions of explained variation are,respectively,84.2%,7.5%and 6.7%for angiosperms,and 45.7%,21.3%and 18.6%for gymnosperms.Our study shows that evolutionary history outpaced current environmental factors in shaping global variation in wood density.
基金supported by the National Key Research and Development Program of China(Grant No.2022YFF0800504)the Major Program of the National Natural Science Foundation of China(Grant No.41991324)the Major Research Plan of the National Natural Science Foundation of China(Grant No.92479106)。
文摘Continental silicate weathering acts as a crucial negative feedback mechanism for removing atmospheric CO_(2) and maintaining Earth's long-term climate stability.However,quantifying continental silicate weathering rates and fluxes continues to pose a fundamental challenge in Earth system science.This study utilizes the GEOCLIM carbon cycle model,which integrates modern high-resolution(0.1°×0.1°)datasets on surface temperature,runoff,topography,and lithology to model the spatial distribution of global silicate weathering fluxes.Results indicate a strong correlation between modeled basin-scale outputs and hydrological observations,with weathering rates falling within consistent error margins.Silicate weathering fluxes exhibit distinct latitudinal patterns,with the highest values concentrated within 30°of the equator,accounting for 76.9%of the global total.Continental contributions differ significantly,with Asian river basins representing 36.9%of global fluxes,primarily from Southeast Asia(17.4%),South Asia(8.2%),and East Asia(6.6%).They are followed by South America(29.2%)and Africa(21.7%).Tectonically active regions contribute 21.9%of global silicate weathering,while stable regions account for 72.6%.Multivariate regression analyses using RF and XGBoost machine learning algorithms identify runoff as the primary controlling factor of weathering on a global scale.Weathering in stable regions is jointly regulated by runoff and erosion rates,whereas temperature is the prevailing factor in tectonically active zones.The GEOCLIM model offers a robust framework for quantifying continental weathering processes.Future studies should incorporate organic carbon oxidation,burial,and sulfide oxidation dynamics to clarify carbon cycle interactions and reveal climate-dependent mechanisms for weathering responses and feedback.
基金supported by the National Natural Science Foundation of China(42225304 and 42293291).
文摘The Cryogenian Sturtian(717–660 Ma)and Marinoan glacial deposits(∼650–635 Ma),typically consisting of alternating layers of glaciogenic diamictite and clast-free lithofacies,indicate dynamic glaciers or glacial-interglacial cycles during the global glaciations.This may result from ice sublimation in tropics under a Snowball Earth condition.However,this model fails to explain the deposition patterns observed in mid-latitude continents.We propose the presence of unfrozen oceans while the continents are covered,i.e.,the icy-continents.The open-ocean condition requires low atmospheric pCO_(2)level.We argued that the mantle CO_(2)degassing could be counterbalanced by a growing pool of dissolved organic carbon(DOC)in the deep ocean,maintaining a small marine dissolved inorganic carbon(DIC)pool and a low atmospheric pCO_(2)level.The persistent marine productivity in the open ocean would support the expanded DOC pool due to reduced ocean ventilation and limited terrestrial inputs of oxidants.However,the global glaciation with open oceans was climatically unstable.The fluctuation of the DOC pool on a local or regional scale likely contributed to the frequent glacial-interglacial oscillations recorded in the rock records.Additionally,the expansion of the DOC pool removed seawater nutrients,e.g.,phosphorus(P),and insufficient nutrient supply prevented the transfer of mantle-degassing carbon as DOC,ultimately leading to the termination of global glaciation.The turnover of the DOC pool,caused by deep ocean ventilation in the deglacial period,significantly increased the atmospheric pCO_(2)level.This event was followed by intense continental weathering,increased seawater pH,recovery of primary productivity,cap carbonate precipitation,and eventually,the emergence of new life forms and innovations in the biosphere.
