Covering extensive parts of China, Karst landscapes are exceptional because rapid and intensive land use change has caused severe ecosystem degradation within only the last 50 years. The twentieth century intensificat...Covering extensive parts of China, Karst landscapes are exceptional because rapid and intensive land use change has caused severe ecosystem degradation within only the last 50 years. The twentieth century intensification in food production through agriculture has led to a rapid deterioration of soil quality, evidenced in reduced crop production and rapid loss of soil. In many areas, a tipping point appears to have been passed as basement rock is exposed and 'rocky desertification' dominates. Through the establishment of the "Soil processes and ecological services in the karst critical zone of SW China"(SPECTRA)Critical Zone Observatory(CZO) we will endevaour to understand the fundmental processes involved in soil production and erosion, and investigate the integrated geophysical-geochemical-ecological responses of the CZ to perturbations. The CZ spans a gradient from undisturbed natural vegetation through human perturbed landscapes.We seek to understand the importance of heterogeneity insurface and below-ground morphology and flow pathways in determining the spatial distribution of key stocks(soil,C, vegetation, etc.) and their control on ecosystem service delivery. We will assess the extent to which the highly heterogeneous critical zone resources can be restored to enable sustainable delivery of ecosystem services. This paper presents the CZO design and initial assessment of soil and soil organic carbon stocks and evidence for their stability based on caesium-137(^(137) Cs) data.展开更多
Rivers link terrestrial ecosystems and marine ecosystems, and they transport large amounts of substances into oceans each year, including several forms of silicon(Si), carbon(C), and other nutrients. However, river da...Rivers link terrestrial ecosystems and marine ecosystems, and they transport large amounts of substances into oceans each year, including several forms of silicon(Si), carbon(C), and other nutrients. However, river damming affects the water flow and biogeochemical cycles of Si, C, and other nutrients through biogeochemical interacting processes. In this review, we first summarize the current understanding of the effects of river damming on the processes of biogeochemical Si cycle, especially the source, composition, and recycling process of biogenic silica(BSi). Then, we introduce dam impacts on the cycles of C and some other nutrients. Dissolved silicon in rivers is mainly released from phytolith dissolution and silicate weathering. BSi in suspended matter or sediments in most rivers mainly consists of phytoliths and mainly originates from soil erosion. However, diatom growth and deposition in many reservoirs formed by river interception may significantly increase the contribution of diatom Si to total BSi, and thus significantly influence the biogeochemical Si,C, and nutrient cycles. Yet the turnover of phytoliths and diatoms in different rivers formed by river damming is still poorly quantified. Thus, they should be further investigated to enhance our understanding about the effects of river damming on global biogeochemical Si, C and nutrient cycles.展开更多
Much attention has been paid to the stoichiometry of carbon(C), nitrogen(N), and phosphorus(P) because of their significance for plant growth and climate change. However, other nutrients, such as sulfur(S), are often ...Much attention has been paid to the stoichiometry of carbon(C), nitrogen(N), and phosphorus(P) because of their significance for plant growth and climate change. However, other nutrients, such as sulfur(S), are often ignored. In this study, we analyzed the stoichiometry of N, P, and S in leaves of 348 plant species in China's forests. The results show higher N content and higher molar ratios of N/P and P/S in Angiospermae than in Gymnospermae. At the family level, Ulmaceae absorbed more N and P from soils than other families, and Cupressaceae absorbed more S than other families. In addition,except for bamboo and other tropical forests, leaf N and P content of China's forests generally increased from low to middle latitudes and then slightly decreased or plateaued at high latitudes. Plant ecotypes, taxonomic groups, environmental conditions, atmospheric S precipitation, and soil-available N and P significantly affected the distribution and stoichiometry of leaf N, P, and S in China's forests.Our study indicates that China's forests are likely limited by P and S deficiencies which may increase in the future.展开更多
Soil degradation, including rocky desertification,of the karst regions in China is severe. Karst landscapes are especially sensitive to soil degradation as carbonate rocks are nutrient-poor and easily eroded. Understa...Soil degradation, including rocky desertification,of the karst regions in China is severe. Karst landscapes are especially sensitive to soil degradation as carbonate rocks are nutrient-poor and easily eroded. Understanding the balance between soil formation and soil erosion is critical for long-term soil sustainability, yet little is known about the initial soil forming processes on karst terrain. Herein we examine the initial weathering processes of several types of carbonate bedrock containing varying amounts of non-carbonate minerals in the SPECTRA Critical Zone Observatory, Guizhou Province, Southwest China. We compared the weathering mechanisms of the bedrock to the mass transfer of mineral nutrients in a soil profile developed on these rocks and found that soil formation and nutrient contents are strongly dependent upon the weathering of interbedded layers of more silicate-rich bedrock(marls). Atmospheric inputs from dust were also detected.展开更多
Topography and land use affect soil organic carbon(SOC) storage, stabilization, and turnover, through several biogeochemical processes. This study investigated the aggregate composition and SOC content of bulk soils a...Topography and land use affect soil organic carbon(SOC) storage, stabilization, and turnover, through several biogeochemical processes. This study investigated the aggregate composition and SOC content of bulk soils and aggregates at different slope positions under different land uses in a typical karst catchment of southwestern China. Our results show that the proportion of macro-aggregates and the SOC content of bulk soils and aggregates at different slope positions decreased from the upper to the lower slope. The SOC content generally increased with an increase in the mean weight diameter and proportion of macro-aggregates under different land uses. Our results indicate that macro-aggregates in forest and grassland soils make a greater contribution to both aggregate composition and SOC content than that in arable land soils. Therefore,converting farmland to forest or grassland can facilitate the accumulation of macro-aggregates as well as the storage of SOC.展开更多
This study investigated the impact of topography and vegetation on distribution of rare earth elements(REEs)in calcareous soils using methods of single extraction and mass balance calculation. The purposes of the stud...This study investigated the impact of topography and vegetation on distribution of rare earth elements(REEs)in calcareous soils using methods of single extraction and mass balance calculation. The purposes of the study were to set a basis for further research on the biogeochemical REE cycle and to provide references for soil–water conservation and REE-containing fertilizer amendments. The results show a generally flat Post-Archean Average Australian Shale—normalized REE pattern for the studied calcareous soils. REE enrichment varied widely. The proportion of acidsoluble phases of heavy REEs was higher than that of light REEs. From top to bottom of the studied hills, dominant REE sources transitioned from limestone in-situ weathering to input from REE-containing phases(e.g., clay minerals,amorphous iron, REE-containing fluids). Our results indicate that the REE content of calcareous soils is mainly controlled by slope aspect, while the enrichment degree of REEs is related to geomorphological position and vegetation type.Furthermore, the proportion of acid-soluble phases of REEs is mainly controlled by geomorphological position.展开更多
Asian dust has been identified in subtropical soils of China.Neodymium(Nd)and lead(Pb)elemental and isotopic geochemistry of soils in Southeast China were used to assess the significance of local versus extraneous sou...Asian dust has been identified in subtropical soils of China.Neodymium(Nd)and lead(Pb)elemental and isotopic geochemistry of soils in Southeast China were used to assess the significance of local versus extraneous sources.The εNd(0)values were close to the parent rocks(+2.9)in the young soils(NSJ);while their values were always negative(〜—3.7)in the old soils(OMJ),implying dust deposition.The young soils contained less Asian dust contribution(<8%)while the old soils contained more than 50%Asian dust contribution.This implied that dust contributions were gradually increasing with the soil development stage and Asian dust input had become the principal Nd source for the old soils in this area.On the other hand,Pb excesses and low 207Pb/206Pb values(〜0.8503)in near-surface soils indicated a significant anthropogenic Pb addition onto surface soils.The close relationship between the Pb content and isotopic ratios in the soil profile indicated that the excessive lead in the surface soil was exogenous.These results suggested that Asian dust made up a significant fraction in the old soils,but that local sources(i.e.,basalt and anthropogenic)were not trivial in Southeast China.展开更多
With the rapid economic expansion, environmental degradation has become increasingly sever during the past three decades. Soil pollutions associated with toxic organic compounds and heavy metals have been identified i...With the rapid economic expansion, environmental degradation has become increasingly sever during the past three decades. Soil pollutions associated with toxic organic compounds and heavy metals have been identified in China. The accumulation of heavy metals in soils and its impact on food safety is of increasing concern. It has been reported that more than 20 million ha of land have been contaminated with heavy metals that can result in the potential health risks to human beings and soil ecosystems. This can potentially jeopardize the food security in China. Accumulation of heavy metals in suburb and rural soils is closely related to many anthropogenic activities, such as application of fertilizers and pesticides, irrigation of wastewater, discharge of mining, improper disposal of metal containing wastes, land application of animal manures, sewage sludge and coal combustion residues. Arable crops and vegetables in suburb and rural can take up heavy metals from contaminated soils, which is one of the main pathways of introducing heavy metals to human food chain. Events related to soil and vegetable contamination, food safety and human health risks, e.g., rice and vegetables with elevated concentrations of cadmium, are often reported in the media in recent years. The Chinese government has recently developed a number of new policies for prevention of soils from further soil contamination, and remediation of contaminated soils. This presentation will provide a comprehensive review on heavy metal pollution in soils and its impacts on food security in China, and also summarize some new technologies for remediation of soils contaminated with heavy metals.展开更多
The distribution development of oak has significant effects on ecosystems and society.Long-term forest distribution studies can help to better understand the vegetation dynamics under climate change or human activitie...The distribution development of oak has significant effects on ecosystems and society.Long-term forest distribution studies can help to better understand the vegetation dynamics under climate change or human activities in the future.In this study,we integrated different methods(i.e.,palaeoecology,phylogeography,and species distribution models)to investigate the likely locations of glacial refugia and the postglacial development of the main deciduous oak species(i.e.,Quercus variabilis,Q.mongolica,Q.dentata,Q.aliena,Q.acutissima and Q.liaotungensis).The results indicated that mountains such as the Changbai,Qinling,and Dabie Mountains acted as the refugia in northern and central China during the Last Glacial Maximum(LGM).The present Quercus in northern China could be the result of local dispersal during the postglacial period rather than only that of long-distance migration from south to north.Climate was the main influencing factor for oak migration,while human activities did not show much influence on this widespread genus.The topography acted as a buffer and made the mountains act as refugia under a deteriorated climate.Compared with other main tree genera(e.g.,Pinus and Betula),the refugia locations and migration routes of deciduous oak species were different because of their physiological differences.The individual migration dynamics of these three genera need to be considered when modelling their dynamics.展开更多
Occlusion of carbon(C) within phytoliths(Phyt OC) is becoming one of the most promising terrestrial C sequestration mechanisms. This study explored the production of Phyt OC within 35 bamboo species belonging to three...Occlusion of carbon(C) within phytoliths(Phyt OC) is becoming one of the most promising terrestrial C sequestration mechanisms. This study explored the production of Phyt OC within 35 bamboo species belonging to three ecotypes using methods of microwave digestion. The aim of this study is to explore the present and potential C sequestration rate within phytoliths of bamboo species from three ecotypes. Phyt OC content in bamboos of three ecotypes ranges from 0.07 % to 0.42 %. The mean Phyt OC production flux decreases as: clustered bamboo(0.050 ±0.016 t CO2ha-1a-1) & mixed bamboo(0.049 ± 0.016 t CO2ha-1a-1) [ scattered bamboo(0.038 ± 0.020 t CO2ha-1a-1). The phytolith carbon sequestration in Chinese bamboo is estimated to be 0.293 ± 0.127 Tg(1 Tg =1012g) CO2a-1; approximately 75 %, 3 %, and 22 % of which is contributed from scattered, mixed and clustered bamboo, respectively. Taking the Phyt OC production flux of 0.18 ± 0.12 t CO2ha-1a-1and current annual area increasing rate of 3 %, global bamboo phytoliths wouldsequester 11.9 ± 7.9 Tg CO2a-1by 2050. Consequently,bamboo forests have significant potential to mitigate the increasing concentration of atmospheric CO2 by maximizing Phyt OC production flux and expanding bamboos.展开更多
基金supported by the National Environmental Research Council of the UK(Grant No.NE/N007603/1)the National Science Foundation of China(Grant Nos.41571130042 and 41571130041)
文摘Covering extensive parts of China, Karst landscapes are exceptional because rapid and intensive land use change has caused severe ecosystem degradation within only the last 50 years. The twentieth century intensification in food production through agriculture has led to a rapid deterioration of soil quality, evidenced in reduced crop production and rapid loss of soil. In many areas, a tipping point appears to have been passed as basement rock is exposed and 'rocky desertification' dominates. Through the establishment of the "Soil processes and ecological services in the karst critical zone of SW China"(SPECTRA)Critical Zone Observatory(CZO) we will endevaour to understand the fundmental processes involved in soil production and erosion, and investigate the integrated geophysical-geochemical-ecological responses of the CZ to perturbations. The CZ spans a gradient from undisturbed natural vegetation through human perturbed landscapes.We seek to understand the importance of heterogeneity insurface and below-ground morphology and flow pathways in determining the spatial distribution of key stocks(soil,C, vegetation, etc.) and their control on ecosystem service delivery. We will assess the extent to which the highly heterogeneous critical zone resources can be restored to enable sustainable delivery of ecosystem services. This paper presents the CZO design and initial assessment of soil and soil organic carbon stocks and evidence for their stability based on caesium-137(^(137) Cs) data.
基金the support from the State's Key Project of Research and Development Plan of China (2016YFA0601002)the National Natural Science Foundation of China (41522207,41571130042)
文摘Rivers link terrestrial ecosystems and marine ecosystems, and they transport large amounts of substances into oceans each year, including several forms of silicon(Si), carbon(C), and other nutrients. However, river damming affects the water flow and biogeochemical cycles of Si, C, and other nutrients through biogeochemical interacting processes. In this review, we first summarize the current understanding of the effects of river damming on the processes of biogeochemical Si cycle, especially the source, composition, and recycling process of biogenic silica(BSi). Then, we introduce dam impacts on the cycles of C and some other nutrients. Dissolved silicon in rivers is mainly released from phytolith dissolution and silicate weathering. BSi in suspended matter or sediments in most rivers mainly consists of phytoliths and mainly originates from soil erosion. However, diatom growth and deposition in many reservoirs formed by river interception may significantly increase the contribution of diatom Si to total BSi, and thus significantly influence the biogeochemical Si,C, and nutrient cycles. Yet the turnover of phytoliths and diatoms in different rivers formed by river damming is still poorly quantified. Thus, they should be further investigated to enhance our understanding about the effects of river damming on global biogeochemical Si, C and nutrient cycles.
基金support from the National Natural Science Foundation of China(41522207,41571130042)the State’s Key Project of Research and Development Plan of China(2016YFA0601002)
文摘Much attention has been paid to the stoichiometry of carbon(C), nitrogen(N), and phosphorus(P) because of their significance for plant growth and climate change. However, other nutrients, such as sulfur(S), are often ignored. In this study, we analyzed the stoichiometry of N, P, and S in leaves of 348 plant species in China's forests. The results show higher N content and higher molar ratios of N/P and P/S in Angiospermae than in Gymnospermae. At the family level, Ulmaceae absorbed more N and P from soils than other families, and Cupressaceae absorbed more S than other families. In addition,except for bamboo and other tropical forests, leaf N and P content of China's forests generally increased from low to middle latitudes and then slightly decreased or plateaued at high latitudes. Plant ecotypes, taxonomic groups, environmental conditions, atmospheric S precipitation, and soil-available N and P significantly affected the distribution and stoichiometry of leaf N, P, and S in China's forests.Our study indicates that China's forests are likely limited by P and S deficiencies which may increase in the future.
基金supported by the National Environmental Research Council of the UK(Grant Nos.NE/N007530/1 and NE/N007603/1)the National Science Foundation of China(Grant No.41571130042)
文摘Soil degradation, including rocky desertification,of the karst regions in China is severe. Karst landscapes are especially sensitive to soil degradation as carbonate rocks are nutrient-poor and easily eroded. Understanding the balance between soil formation and soil erosion is critical for long-term soil sustainability, yet little is known about the initial soil forming processes on karst terrain. Herein we examine the initial weathering processes of several types of carbonate bedrock containing varying amounts of non-carbonate minerals in the SPECTRA Critical Zone Observatory, Guizhou Province, Southwest China. We compared the weathering mechanisms of the bedrock to the mass transfer of mineral nutrients in a soil profile developed on these rocks and found that soil formation and nutrient contents are strongly dependent upon the weathering of interbedded layers of more silicate-rich bedrock(marls). Atmospheric inputs from dust were also detected.
基金supported jointly by the National Natural Science Foundation of China(4132501041571130042)the State’s Key Project of Research and Development Plan of China(2016YFA0601002)
文摘Topography and land use affect soil organic carbon(SOC) storage, stabilization, and turnover, through several biogeochemical processes. This study investigated the aggregate composition and SOC content of bulk soils and aggregates at different slope positions under different land uses in a typical karst catchment of southwestern China. Our results show that the proportion of macro-aggregates and the SOC content of bulk soils and aggregates at different slope positions decreased from the upper to the lower slope. The SOC content generally increased with an increase in the mean weight diameter and proportion of macro-aggregates under different land uses. Our results indicate that macro-aggregates in forest and grassland soils make a greater contribution to both aggregate composition and SOC content than that in arable land soils. Therefore,converting farmland to forest or grassland can facilitate the accumulation of macro-aggregates as well as the storage of SOC.
基金supported jointly by the National Natural Science Foundation of China(41571130042,41522207,41325010)the State’s Key Project of Research and Development Plan of China(2016YFA0601002)
文摘This study investigated the impact of topography and vegetation on distribution of rare earth elements(REEs)in calcareous soils using methods of single extraction and mass balance calculation. The purposes of the study were to set a basis for further research on the biogeochemical REE cycle and to provide references for soil–water conservation and REE-containing fertilizer amendments. The results show a generally flat Post-Archean Average Australian Shale—normalized REE pattern for the studied calcareous soils. REE enrichment varied widely. The proportion of acidsoluble phases of heavy REEs was higher than that of light REEs. From top to bottom of the studied hills, dominant REE sources transitioned from limestone in-situ weathering to input from REE-containing phases(e.g., clay minerals,amorphous iron, REE-containing fluids). Our results indicate that the REE content of calcareous soils is mainly controlled by slope aspect, while the enrichment degree of REEs is related to geomorphological position and vegetation type.Furthermore, the proportion of acid-soluble phases of REEs is mainly controlled by geomorphological position.
基金the China Natural Science Foundation(Nos.41877006 and 41930862)we also express great thanks to Hailong Wang for his assistance in language polishing.
文摘Asian dust has been identified in subtropical soils of China.Neodymium(Nd)and lead(Pb)elemental and isotopic geochemistry of soils in Southeast China were used to assess the significance of local versus extraneous sources.The εNd(0)values were close to the parent rocks(+2.9)in the young soils(NSJ);while their values were always negative(〜—3.7)in the old soils(OMJ),implying dust deposition.The young soils contained less Asian dust contribution(<8%)while the old soils contained more than 50%Asian dust contribution.This implied that dust contributions were gradually increasing with the soil development stage and Asian dust input had become the principal Nd source for the old soils in this area.On the other hand,Pb excesses and low 207Pb/206Pb values(〜0.8503)in near-surface soils indicated a significant anthropogenic Pb addition onto surface soils.The close relationship between the Pb content and isotopic ratios in the soil profile indicated that the excessive lead in the surface soil was exogenous.These results suggested that Asian dust made up a significant fraction in the old soils,but that local sources(i.e.,basalt and anthropogenic)were not trivial in Southeast China.
文摘With the rapid economic expansion, environmental degradation has become increasingly sever during the past three decades. Soil pollutions associated with toxic organic compounds and heavy metals have been identified in China. The accumulation of heavy metals in soils and its impact on food safety is of increasing concern. It has been reported that more than 20 million ha of land have been contaminated with heavy metals that can result in the potential health risks to human beings and soil ecosystems. This can potentially jeopardize the food security in China. Accumulation of heavy metals in suburb and rural soils is closely related to many anthropogenic activities, such as application of fertilizers and pesticides, irrigation of wastewater, discharge of mining, improper disposal of metal containing wastes, land application of animal manures, sewage sludge and coal combustion residues. Arable crops and vegetables in suburb and rural can take up heavy metals from contaminated soils, which is one of the main pathways of introducing heavy metals to human food chain. Events related to soil and vegetable contamination, food safety and human health risks, e.g., rice and vegetables with elevated concentrations of cadmium, are often reported in the media in recent years. The Chinese government has recently developed a number of new policies for prevention of soils from further soil contamination, and remediation of contaminated soils. This presentation will provide a comprehensive review on heavy metal pollution in soils and its impacts on food security in China, and also summarize some new technologies for remediation of soils contaminated with heavy metals.
基金supported by the National Key Research and Development Program of China(Grant No.2017YFA0605101)。
文摘The distribution development of oak has significant effects on ecosystems and society.Long-term forest distribution studies can help to better understand the vegetation dynamics under climate change or human activities in the future.In this study,we integrated different methods(i.e.,palaeoecology,phylogeography,and species distribution models)to investigate the likely locations of glacial refugia and the postglacial development of the main deciduous oak species(i.e.,Quercus variabilis,Q.mongolica,Q.dentata,Q.aliena,Q.acutissima and Q.liaotungensis).The results indicated that mountains such as the Changbai,Qinling,and Dabie Mountains acted as the refugia in northern and central China during the Last Glacial Maximum(LGM).The present Quercus in northern China could be the result of local dispersal during the postglacial period rather than only that of long-distance migration from south to north.Climate was the main influencing factor for oak migration,while human activities did not show much influence on this widespread genus.The topography acted as a buffer and made the mountains act as refugia under a deteriorated climate.Compared with other main tree genera(e.g.,Pinus and Betula),the refugia locations and migration routes of deciduous oak species were different because of their physiological differences.The individual migration dynamics of these three genera need to be considered when modelling their dynamics.
基金We thank Yanbin Cai for helping with the rice treatments. The work was supported by the National Natural Science Foundation of China （41103042）, the Field Frontier Project of Insti- tute of Geochemistry. Chinese Academy of Sciences （2045200295）. the Training Program for the Top Young Talents of Zhejiang Agri- cultural and Forestry University （2034070001）. and the Program for the Distinguished Young and middle-aged Academic Leaders of Higher Education Institutions of Zhejiang Province （PD2013240）.
基金supported by the National Natural Science Foundation of China(41103042)the Field Frontier Project of Institute of Geochemistry,Chinese Academy of Sciences(2045200295)+2 种基金the Training Program for the Top Young Talents of Zhejiang Agricultural and Forestry University(2034070001)the Program for the Third Layer of 151 Talents Project of ZhejiangProvince(2035110003)the Program for the Distinguished Young and middle-aged Academic Leaders of Higher Education Institutions of Zhejiang Province(PD2013240)
文摘Occlusion of carbon(C) within phytoliths(Phyt OC) is becoming one of the most promising terrestrial C sequestration mechanisms. This study explored the production of Phyt OC within 35 bamboo species belonging to three ecotypes using methods of microwave digestion. The aim of this study is to explore the present and potential C sequestration rate within phytoliths of bamboo species from three ecotypes. Phyt OC content in bamboos of three ecotypes ranges from 0.07 % to 0.42 %. The mean Phyt OC production flux decreases as: clustered bamboo(0.050 ±0.016 t CO2ha-1a-1) & mixed bamboo(0.049 ± 0.016 t CO2ha-1a-1) [ scattered bamboo(0.038 ± 0.020 t CO2ha-1a-1). The phytolith carbon sequestration in Chinese bamboo is estimated to be 0.293 ± 0.127 Tg(1 Tg =1012g) CO2a-1; approximately 75 %, 3 %, and 22 % of which is contributed from scattered, mixed and clustered bamboo, respectively. Taking the Phyt OC production flux of 0.18 ± 0.12 t CO2ha-1a-1and current annual area increasing rate of 3 %, global bamboo phytoliths wouldsequester 11.9 ± 7.9 Tg CO2a-1by 2050. Consequently,bamboo forests have significant potential to mitigate the increasing concentration of atmospheric CO2 by maximizing Phyt OC production flux and expanding bamboos.
