The litterbag method was used to study the decomposition of wetland plant root in three wetlands along a water level gradient in the Sanjiang Plain,Northeast China.These wetlands are Calamagrostis angustifolia(C.aa),C...The litterbag method was used to study the decomposition of wetland plant root in three wetlands along a water level gradient in the Sanjiang Plain,Northeast China.These wetlands are Calamagrostis angustifolia(C.aa),Carex meyeriana(C.ma)and Carex lasiocarpa (C.la).The objective of our study is to evaluate the influence of environment and substrate quality on decomposition rates in the three wetlands.Calico material was used as a standard substrate to evaluate environmental influences.Roots native to each we...展开更多
The effect of a self-organized SiNs interlayer on the defect density of （1122） semipolar GaN grown on 7n-plane sapphire is studied by transmission electron microscopy, atomic force microscopy and high resolution x-r...The effect of a self-organized SiNs interlayer on the defect density of （1122） semipolar GaN grown on 7n-plane sapphire is studied by transmission electron microscopy, atomic force microscopy and high resolution x-ray diffrac- tion. The SiNx interlayer reduces the c-type dislocation density from 2.5 ×10^10 cm^-2 to 5 ×10^8 cm 2. The SiNx interlayer produces regions that are free from basal plane stacking faults （BSFs） and dislocations. The overall BSF density is reduced from 2.1×10^5 cm-1 to 1.3×10^4 cm^-1. The large dislocations and BSF reduction in semipolar （1122） GaN with the SiNx, interlayer result from two primary mechanisms. The first mechanism is the direct dislocation blocking by the SiNx interlayer, and the second mechanism is associated with the unique structure character of （1122） semipolar GaN.展开更多
A field study was conducted to evaluate the protozoan colonization patterns on artificial substrates in relation to organic pollution within a tropical harbour. The composition of protozoans and their succession rate...A field study was conducted to evaluate the protozoan colonization patterns on artificial substrates in relation to organic pollution within a tropical harbour. The composition of protozoans and their succession rates on artificial substrates(polyurethane foam units) were compared between two field stations(A and B), and their presence were considered with regards to the prevailing water quality conditions at the study sites. Altogether 44 genera of flagellates and ciliates were documented. The common genera of flagellates encountered included Monas, Polytoma, and Chromalina. Among the ciliates, the predominant genera were Tetrahymena, Vorticella, Lagynophyra, and Heloiphyra. These groups exhibited characteristic successional patterns in relation to ambient water quality. At Station A, located close to the sewage outfall, the water quality parameters included poor Secchi disc transparency(0.48m), dissolved oxygen of 1.93 mg/ml, salinity of 18 psu, and temperature 31.3 ℃. Here, the nanoflagellates( spumella ) colonized first, followed by microcilliate( Tetrahymena ) and sessile form( Vorticella ). Station B, located on the seaward side, was characterized by relatively less stressed environmental conditions with transparency 1.85m and dissolved oxygen value of 6 04 mg/ml. Salinity of 27.27 psu, and mean temperature of 30 ℃ were recorded at “B'. At this station, the nanoflagellate Polytoma was first documented to colonize on the substrates, followed by microcilliate( Lagynophrya ) and suctorid( Heliophyra ). These findings support the use of protozoans as indicator species for evaluating the hazards posed by organic pollution to natural estuarine communities.展开更多
Inorganic nitrogen(N)loss through sediment N mineralization is important for eutrophication surrounding riparian zone.Sediment physicochemical properties have been changed at water-level elevation in riparian zone of ...Inorganic nitrogen(N)loss through sediment N mineralization is important for eutrophication surrounding riparian zone.Sediment physicochemical properties have been changed at water-level elevation in riparian zone of the Three Gorges Reservoir(TGR)due to differences in hydrological stress and human activity intensity.However,spatial distribution and driving factor of net N mineralization rate(Nmin)and its temperature sensitivity(Q10)based on the changes in sediment physicochemical properties are still unclear at waterlevel elevation in the riparian zone.A total of 132 sediment samples in the riparian zone were collected including 11 transections and 12 water-level elevations on basin scale of the TGR during drying period,to conduct a 28-day incubation at 15℃,22℃,29℃and 36℃.Nmin,total N(TN)and substrate quality(SQ)increased with water-level elevation,while Q10 showed an opposite trend(P<0.001).Results of the structural equation model showed that water-level elevation had direct positive effects on TN and SQ(P<0.01).In addition,TN was the major factor that had a direct positive effect on Nmin,and SQ was the crucial factor that had a direct negative effect on Q10(P<0.001).In conclusion,increases in TN and SQ were major driving factors of Nmin and its Q10 at water-level elevation,respectively,in riparian zone of the TGR during drying period.展开更多
Subsoils hold a substantial reservoir of organic carbon(C),and its dynamics can be greatly influenced by fresh C inputs through priming effect,potentially altering the magnitude of soil C-climate feedback.Despite the ...Subsoils hold a substantial reservoir of organic carbon(C),and its dynamics can be greatly influenced by fresh C inputs through priming effect,potentially altering the magnitude of soil C-climate feedback.Despite the importance of soil C dynamics in regulating this feedback,our understanding of how soil C release and the priming effect vary along the soil profile remains limited,especially in alpine grasslands on the Tibetan Plateau.In particular,the relative importance of abiotic and biotic factors,such as soil physicochemical properties,aggregate and mineral protection,substrate quantity and quality,and plant and microbial properties(e.g.,microbial biomass and diversity),in mediating vertical variations in soil C release and the priming effect is still unclear.Using 1-meter-deep soil profiles from five sites on the plateau,our~(13)C isotope labeling incubation experiments revealed a significant decline in both C release and the priming effect with increasing soil depth.We found that variations in soil C release along the profile were primarily influenced by soil properties(soil moisture and p H),mineral protection(the molar ratios of amorphous Fe/Al oxides to soil organic C(SOC)and soil mineral specific surface area),and hydrolase activity.In addition,vertical variations in the priming effect were dominantly affected by soil properties(soil moisture and p H),mineral and aggregate protection(the molar ratio of exchangeable Ca to SOC and the proportion of C occluded in clay+silt fractions),and microbial properties(oxidase activity and the copy number of bacterial ribosomal RNA gene operons).These findings provide valuable insights into the complex soil C cycling across profiles and its feedback to climate change.展开更多
Understanding the temperature and moisture sensitivity of soil organic matter （SOM） mineralization variations with changes in land cover is critical for assessing soil carbon （C） storage under global change scenar...Understanding the temperature and moisture sensitivity of soil organic matter （SOM） mineralization variations with changes in land cover is critical for assessing soil carbon （C） storage under global change scenarios We determined the differences in the amount of SOM mineralization and the temperature and moisture sensitivity of soils collected from six land-cover types, including an orchard, a cropland, and four forests, in subtropical south- eastern China. The responses of SOM mineralization to temperature （5, 10, 15, 20, and 25~C） and moisture （30%, 60%, and 90% of water-holding capacity [WHC]） were investigated by placing soil samples in incubators. Soil C mineralization rate and cumulative C mineralization were higher in orchard and cropland soils than in other forest soils. With increasing temperature, soil C mineralization rates and cumulative C mineralization increased with the rise of WHCo The temperature sensitivity of soil C mineralization was not affected by land-cover type and incubation moisture. All soil temperature treatments showed a similar response to moisture. Cropland soil was more respon- sive to soil moisture than other soils. Our findings indicate that cropland and orchard soils have a higher ability to emit CO2 than forest soils in subtropical southeastern China.展开更多
Microbial carbon use efficiency(CUE)is an important factor driving soil carbon(C)dynamics.However,microbial CUE could positively,negatively,or neutrally respond to increased temperature,which limits our prediction of ...Microbial carbon use efficiency(CUE)is an important factor driving soil carbon(C)dynamics.However,microbial CUE could positively,negatively,or neutrally respond to increased temperature,which limits our prediction of soil C storage under future climate warming.Experimental warming affects plant production and microbial communities,which thus can have a significant impact on biogeochemical cycles of terrestrial ecosystems.Here,we reviewed the present research status of methods measuring microbial CUE and the response of microbial CUE to the changes of biotic and abiotic factors induced by warming.Overall,current measurement methods mainly include metabolic flux analysis,calorespirometry,stoichiometric model,13C and 18O labeling.Differences in added substrate types can lead to an overestimation or underestimation on microbial CUE,particularly when using the 13C labeling method.In addition,changes in the dominant microbial community under warming may also affect CUE.However,there is still uncertainty in CUE characteristics of different microorganisms.Microbial CUE is generally decreased under warming conditions as microbes are subjected to water stress or soil labile organic matter is much more depleted compared to ambient conditions.In contrast,considering that warming increases soil nutrient availability,warming may enhance microbial CUE by alleviating nutrient limitations for microbes.In conclusion,the response of microbial CUE to warming is more complex than expected.The microbial growth and physiological adaptation to environmental stress under warming is one of the main reasons for the inconsistence in microbial CUE response.Finally,we propose five aspects where further research could improve the understanding of microbial CUE in a warmer world,including using new technologies,establishing multi-factor interactive experiments,building a network of experimental research platform for warming,and strengthening studies on response of CUE to warming at different soil depths and on different temporal scales.展开更多
基金supported by the Key Knowledge In-novation Project of Chinese Academy of Science(No.KSCX2-YW-N-46-06).
文摘The litterbag method was used to study the decomposition of wetland plant root in three wetlands along a water level gradient in the Sanjiang Plain,Northeast China.These wetlands are Calamagrostis angustifolia(C.aa),Carex meyeriana(C.ma)and Carex lasiocarpa (C.la).The objective of our study is to evaluate the influence of environment and substrate quality on decomposition rates in the three wetlands.Calico material was used as a standard substrate to evaluate environmental influences.Roots native to each we...
基金Supported by the National Natural Science Foundation of China under Grant Nos 61204006 and 61574108the Fundamental Research Funds for the Central Universities under Grant No JB141101the Foundation of Key Laboratory of Nanodevices and Applications of Suzhou Institute of Nano-Tech and Nano-Bionics of Chinese Academy of Sciences under Grant No 15CS01
文摘The effect of a self-organized SiNs interlayer on the defect density of （1122） semipolar GaN grown on 7n-plane sapphire is studied by transmission electron microscopy, atomic force microscopy and high resolution x-ray diffrac- tion. The SiNx interlayer reduces the c-type dislocation density from 2.5 ×10^10 cm^-2 to 5 ×10^8 cm 2. The SiNx interlayer produces regions that are free from basal plane stacking faults （BSFs） and dislocations. The overall BSF density is reduced from 2.1×10^5 cm-1 to 1.3×10^4 cm^-1. The large dislocations and BSF reduction in semipolar （1122） GaN with the SiNx, interlayer result from two primary mechanisms. The first mechanism is the direct dislocation blocking by the SiNx interlayer, and the second mechanism is associated with the unique structure character of （1122） semipolar GaN.
文摘A field study was conducted to evaluate the protozoan colonization patterns on artificial substrates in relation to organic pollution within a tropical harbour. The composition of protozoans and their succession rates on artificial substrates(polyurethane foam units) were compared between two field stations(A and B), and their presence were considered with regards to the prevailing water quality conditions at the study sites. Altogether 44 genera of flagellates and ciliates were documented. The common genera of flagellates encountered included Monas, Polytoma, and Chromalina. Among the ciliates, the predominant genera were Tetrahymena, Vorticella, Lagynophyra, and Heloiphyra. These groups exhibited characteristic successional patterns in relation to ambient water quality. At Station A, located close to the sewage outfall, the water quality parameters included poor Secchi disc transparency(0.48m), dissolved oxygen of 1.93 mg/ml, salinity of 18 psu, and temperature 31.3 ℃. Here, the nanoflagellates( spumella ) colonized first, followed by microcilliate( Tetrahymena ) and sessile form( Vorticella ). Station B, located on the seaward side, was characterized by relatively less stressed environmental conditions with transparency 1.85m and dissolved oxygen value of 6 04 mg/ml. Salinity of 27.27 psu, and mean temperature of 30 ℃ were recorded at “B'. At this station, the nanoflagellate Polytoma was first documented to colonize on the substrates, followed by microcilliate( Lagynophrya ) and suctorid( Heliophyra ). These findings support the use of protozoans as indicator species for evaluating the hazards posed by organic pollution to natural estuarine communities.
基金supported by the Program of Chongqing Science and Technology Commission(cstc2020jcyj-msxmX0095)the Science and Technology Research Program of Chongqing Municipal Education Commission(KJZDK202001203,KJZD-K202003501)the Innovative Research Group of Universities in Chongqing(CXQT P19037).
文摘Inorganic nitrogen(N)loss through sediment N mineralization is important for eutrophication surrounding riparian zone.Sediment physicochemical properties have been changed at water-level elevation in riparian zone of the Three Gorges Reservoir(TGR)due to differences in hydrological stress and human activity intensity.However,spatial distribution and driving factor of net N mineralization rate(Nmin)and its temperature sensitivity(Q10)based on the changes in sediment physicochemical properties are still unclear at waterlevel elevation in the riparian zone.A total of 132 sediment samples in the riparian zone were collected including 11 transections and 12 water-level elevations on basin scale of the TGR during drying period,to conduct a 28-day incubation at 15℃,22℃,29℃and 36℃.Nmin,total N(TN)and substrate quality(SQ)increased with water-level elevation,while Q10 showed an opposite trend(P<0.001).Results of the structural equation model showed that water-level elevation had direct positive effects on TN and SQ(P<0.01).In addition,TN was the major factor that had a direct positive effect on Nmin,and SQ was the crucial factor that had a direct negative effect on Q10(P<0.001).In conclusion,increases in TN and SQ were major driving factors of Nmin and its Q10 at water-level elevation,respectively,in riparian zone of the TGR during drying period.
基金supported by the National Key Research and Development Program of China(2022YFF0801901)the National Natural Science Foundation of China(32425004)the New Cornerstone Science Foundation through the XPLORER PRIZE。
文摘Subsoils hold a substantial reservoir of organic carbon(C),and its dynamics can be greatly influenced by fresh C inputs through priming effect,potentially altering the magnitude of soil C-climate feedback.Despite the importance of soil C dynamics in regulating this feedback,our understanding of how soil C release and the priming effect vary along the soil profile remains limited,especially in alpine grasslands on the Tibetan Plateau.In particular,the relative importance of abiotic and biotic factors,such as soil physicochemical properties,aggregate and mineral protection,substrate quantity and quality,and plant and microbial properties(e.g.,microbial biomass and diversity),in mediating vertical variations in soil C release and the priming effect is still unclear.Using 1-meter-deep soil profiles from five sites on the plateau,our~(13)C isotope labeling incubation experiments revealed a significant decline in both C release and the priming effect with increasing soil depth.We found that variations in soil C release along the profile were primarily influenced by soil properties(soil moisture and p H),mineral protection(the molar ratios of amorphous Fe/Al oxides to soil organic C(SOC)and soil mineral specific surface area),and hydrolase activity.In addition,vertical variations in the priming effect were dominantly affected by soil properties(soil moisture and p H),mineral and aggregate protection(the molar ratio of exchangeable Ca to SOC and the proportion of C occluded in clay+silt fractions),and microbial properties(oxidase activity and the copy number of bacterial ribosomal RNA gene operons).These findings provide valuable insights into the complex soil C cycling across profiles and its feedback to climate change.
基金Natural Sciences Foundation of China(31270519,31470506,31130009,31290221)
文摘Understanding the temperature and moisture sensitivity of soil organic matter （SOM） mineralization variations with changes in land cover is critical for assessing soil carbon （C） storage under global change scenarios We determined the differences in the amount of SOM mineralization and the temperature and moisture sensitivity of soils collected from six land-cover types, including an orchard, a cropland, and four forests, in subtropical south- eastern China. The responses of SOM mineralization to temperature （5, 10, 15, 20, and 25~C） and moisture （30%, 60%, and 90% of water-holding capacity [WHC]） were investigated by placing soil samples in incubators. Soil C mineralization rate and cumulative C mineralization were higher in orchard and cropland soils than in other forest soils. With increasing temperature, soil C mineralization rates and cumulative C mineralization increased with the rise of WHCo The temperature sensitivity of soil C mineralization was not affected by land-cover type and incubation moisture. All soil temperature treatments showed a similar response to moisture. Cropland soil was more respon- sive to soil moisture than other soils. Our findings indicate that cropland and orchard soils have a higher ability to emit CO2 than forest soils in subtropical southeastern China.
基金This work was financially supported by the National Natural Science Foundation of China(32101330,42141006 and 31988102)the China Postdoctoral Science Foundation(2021M690217).
文摘Microbial carbon use efficiency(CUE)is an important factor driving soil carbon(C)dynamics.However,microbial CUE could positively,negatively,or neutrally respond to increased temperature,which limits our prediction of soil C storage under future climate warming.Experimental warming affects plant production and microbial communities,which thus can have a significant impact on biogeochemical cycles of terrestrial ecosystems.Here,we reviewed the present research status of methods measuring microbial CUE and the response of microbial CUE to the changes of biotic and abiotic factors induced by warming.Overall,current measurement methods mainly include metabolic flux analysis,calorespirometry,stoichiometric model,13C and 18O labeling.Differences in added substrate types can lead to an overestimation or underestimation on microbial CUE,particularly when using the 13C labeling method.In addition,changes in the dominant microbial community under warming may also affect CUE.However,there is still uncertainty in CUE characteristics of different microorganisms.Microbial CUE is generally decreased under warming conditions as microbes are subjected to water stress or soil labile organic matter is much more depleted compared to ambient conditions.In contrast,considering that warming increases soil nutrient availability,warming may enhance microbial CUE by alleviating nutrient limitations for microbes.In conclusion,the response of microbial CUE to warming is more complex than expected.The microbial growth and physiological adaptation to environmental stress under warming is one of the main reasons for the inconsistence in microbial CUE response.Finally,we propose five aspects where further research could improve the understanding of microbial CUE in a warmer world,including using new technologies,establishing multi-factor interactive experiments,building a network of experimental research platform for warming,and strengthening studies on response of CUE to warming at different soil depths and on different temporal scales.
