Based on mass balance theory and IsoSource program,stable carbon and nitrogen isotopic ratios revealed that small mammals (plateau pika,root vole and plateau zokor) contributed 26.8% and 27.0% and 29.2% to alpine weas...Based on mass balance theory and IsoSource program,stable carbon and nitrogen isotopic ratios revealed that small mammals (plateau pika,root vole and plateau zokor) contributed 26.8% and 27.0% and 29.2% to alpine weasel,steppe polecat and upland buzzard of carnivores as food respectively;adult passerine birds contributed 22.3%,47.7% and 69.1%,with hatchlings contributing 50.9%,25.6% and 1.70% to each respectively.δ 13 C values plotted against δ 15 N indicated significant partitioning in two-dimensional space among the three carnivores.It was reasonable to propose a food resource partitioning among alpine weasel,steppe polecat and upland buzzard,which partially revealed their co-existence mechanisms.展开更多
Though aboveground biomass(AGB) has an important contribution to the global carbon cycle,the information about storage and climatic effects of AGB is scare in Three-River Source Region(TRSR)shrub ecosystems. This stud...Though aboveground biomass(AGB) has an important contribution to the global carbon cycle,the information about storage and climatic effects of AGB is scare in Three-River Source Region(TRSR)shrub ecosystems. This study investigated AGB storage and its climatic controls in the TRSR alpine shrub ecosystems using data collected from 23 sites on the Tibetan Plateau from 2011 to 2013. We estimated the AGB storage(both shrub layer biomass and grass layer biomass) in the alpine shrubs as 37.49 Tg, with an average density of 1447.31 g m^(-2). Biomass was primarily accumulated in the shrub layer, which accounted for 92% of AGB, while the grass layer accounted for only 8%. AGB significantly increased with the mean annual temperature(P < 0.05). The effects of the mean annual precipitation on AGB were not significant. These results suggest that temperature,rather than precipitation, has significantly effects on of aboveground vegetation growth in the TRSR alpine shrub ecosystems. The actual and potential increase in AGB density was different due to global warming varies among different regions of the TRSR. We conclude that long-term monitoring of dynamic changes is necessary to improve the accuracy estimations of potential AGB carbon sequestration across the TRSR alpine shrub ecosystems.展开更多
This work addressed the multi-objective optimization of a biogas production system considering both environmental and economic criteria. A mixed integer non-linear programming(MINLP) model was established and solved w...This work addressed the multi-objective optimization of a biogas production system considering both environmental and economic criteria. A mixed integer non-linear programming(MINLP) model was established and solved with non-dominated sorting genetic algorithm Ⅱ, from which the Pareto fronts, the optimal technology combinations and operation conditions were obtained and analyzed. It's found that the system is feasible in both environmental and economic considerations after optimization. The most expensive processing section is decarbonization; the most expensive equipment is anaerobic digester; the most power-consuming processing section is digestion, followed by decarbonization and waste management. The positive green degree value on the process is attributed to processing section of digestion and waste management. 3:1 chicken feces and corn straw, solar energy, pressure swing adsorption and 3:1 chicken feces and rice straw, solar energy, pressure swing adsorption are turned out to be two robust technology combinations under different prices of methane and electricity by sensitivity analysis. The optimization results provide support for optimal design and operation of biogas production system considering environmental and economic objectives.展开更多
Evergreen broad-leaved forestis one of the most important vegetation types in China.Because of the human activities,evergreen broad-leaved forest has been destroyed extensively,leading to degraded ecosystem.It is urge...Evergreen broad-leaved forestis one of the most important vegetation types in China.Because of the human activities,evergreen broad-leaved forest has been destroyed extensively,leading to degraded ecosystem.It is urgent to conserve and restore these natural forests in China. In this paper,the tendency and rate of species diversity restoration of the evergreen broad-leaved forest in Daming Mountain has been studied.The main resultsare as follows:(a)In subtropical mid-mountain area,species diversity in degraded evergreen broad-leaved forestcan be restored. Through analyzing b diversity index of communities in different time and space,it was found that the species composition of communities tend to be the same as that in the zonal evergreen broad-leaved forest.(b)The restoration rate of evergreen broad-leaved forest was very fast.Planting Chinese fir after clear-cutting and controlled burning of the forest,178 species appeared in a 600m^2 sample area after 20 years’natural recovering.Among the sespecies,58 were tree layer and the height of community reached 18m.The survey suggested that it would take only 20 years for the degraded forest to develop into community composed of lightdemanding broad-leaved pioneer trees and min-tolerance broad-leaved trees,and it need another 40~80 years to reach the stage consisting of min-tolerance evergreen broad-leaved trees.(c)Species number increased quickly at the early stage(2-20years)during vegetation recovering process toward the climax,and decreased at the min-stage (50-60 years),then maintained a relatively stable level at the late-stage (over 150 years).展开更多
Allochthonous organic matter plays an important role in nutrient cycling and energy mobilization in freshwater ecosystems. However, the subsidies of this carbon source in floodplain ecosystems have not yet well unders...Allochthonous organic matter plays an important role in nutrient cycling and energy mobilization in freshwater ecosystems. However, the subsidies of this carbon source in floodplain ecosystems have not yet well understood. We used a Bayesian mixing model and stable isotopes (613C and 815N) of primary food resources and dominant molluscs species, to estimate the relative importance of allochthonous carbon sources for consumers in a representative sub-lake of Poyang Lake during a prolonged dry season. Our study inferred that terrestrial-derived carbon from Carex spp. could be the primary contributor to snails and mussels in Dahuchi Lake. The mean percentage of allochthonous food resources accounted for 35%- 50% of the C incorporated by these consumers. Seston was another important energy sources for benthic consumers. However, during the winter and low water-level period, benthic algae and submerged vegetation contributed less carbon to benthic consumers. Our data highlighted the importance of terrestrial organic carbon to benthic consumers in the wetlands of Poyang Lake during the prolonged dry period. Further, our results provided a perspective that linkages between terrestrial and aquatic ecosystems might be facilitated by wintering geese via their droppings.展开更多
By using field survey data from the sixth forest inventory of Jiangxi Province in 2003,the biomass and carbon storage for three studied species(Pinus massoniana,Cunninghamia lanceolata,and Pinus elliottii)were estimat...By using field survey data from the sixth forest inventory of Jiangxi Province in 2003,the biomass and carbon storage for three studied species(Pinus massoniana,Cunninghamia lanceolata,and Pinus elliottii)were estimated in Taihe and Xingguo counties of Boyang Lake Basin,Jiangxi Province,China.The relationship between carbon density and forest age was analyzed by logistic equations.Spatio-temporal dynamics of forest biomass and carbon storage in 1985–2003 were also described.The results show that total stand area of the three forest species was 3.10×105ha,total biomass 22.20 Tg,vegetation carbon storage 13.07 Tg C,and average carbon density 42.36 Mg C/ha in the study area in 2003.Carbon storage by forest type in descending order was:P.massoniana,C.lanceolata and P.elliottii.Carbon storage by forest age group in descending order was:middle stand,young stand,near-mature stand and mature stand.Carbon storage by plantation forests was 1.89 times higher than that by natural forests.Carbon density of the three species increased 8.58 Mg C/ha during the study period.The carbon density of Taihe County was higher in the east and west,and lower in the middle.The carbon density of Xingguo County was higher in the northeast and lower in the middle.In general,the carbon density increased with altitude and gradient.Afforestation projects contribute significantly to increasing stand area and carbon storage.Appropriate forest management may improve the carbon sequestration capacity of forest ecosystems.展开更多
Puget Sound shorelines have historically provided a diversity of habitats that support a variety of aquatic resources throughout the area. These valued natural resources are iconic to the region and remain central to ...Puget Sound shorelines have historically provided a diversity of habitats that support a variety of aquatic resources throughout the area. These valued natural resources are iconic to the region and remain central to both the economic vitality and community appreciation of Puget Sound. Coastal developments over the past 30 years have placed increased pressure on aquatic resources through deterioration of upland and nearshore shoreline habitats within the region. Since a majority of Washington State upland shorelines are privately owned, regulatory authority to require future restoration on private property is not feasible. Washington States' Shoreline Management Act requires local jurisdictions to plan for appropriate future shoreline uses. Under the Act, future development can be regulated to protect existing ecological functions. However, lost functions cannot be retroactively restored through regulatory means, but rather require purchase or compensation of the private property to be restored. Therefore, questions remain as to the ecological resilience of the region when considering cumulative effects of existing and ongoing shoreline development and limited shoreline restoration opportunities constrained to public lands. In light of these questions, this analysis will explore opportunities to promote restoration on privately owned shorelines within Puget Sound. These efforts are intended to promote more efficient coastal management to improve ecosystem services.展开更多
The large reserves ofoil are disposed in zones of permafrost in shelf and continental fields. In Europe the subarctic and arctic tundra are abundant only in Nenetsky autonomous area and in the north-east of the republ...The large reserves ofoil are disposed in zones of permafrost in shelf and continental fields. In Europe the subarctic and arctic tundra are abundant only in Nenetsky autonomous area and in the north-east of the republic of Komi. Oil and gas production activity has threatened richest biological resources and health of the population of the region. A singularity of petroliferous fields of the north of Russia is the existence of the thick strata of permafrost. On top of them different heat-insulating overlying layers (snow, biogenic covers) reside. State and dynamics of permafrost cause progressing dangerous exogenic geoecological processes, which are exhibited completely. State of permafrost is instituted by exchange of heat in near-surface strata of a geological section. During the development of oil fields there is a disturbance of a temperature schedule of permafrost. For estimation of technical attack the analytical computational method of influence of the different factors on value of annual heat exchange and prediction of geocryological conditions is proposed. It is shown, that such dangerous phenomena as degradation of permafrost and thermokarst would develop in the first place, which would cause the destruction of natural ecosystems.展开更多
The climate,mainly the water availability and temperature,drives the renewal of biomass inseasonal forest ecosystem,and the greenness and leaf area of its canopy are responsive climate variations.This study verified ...The climate,mainly the water availability and temperature,drives the renewal of biomass inseasonal forest ecosystem,and the greenness and leaf area of its canopy are responsive climate variations.This study verified models to explain the phenomenon of leaf production and deciduousness by time,with LAI(Leaf Area Index),NDVI(Normalized Difference VegetationIndex)and climate variables,on period 2011-2016. The data were obtained in satellite images and in plots installed at forestmonitoring sites,visited monthly.The analysis incorporated the water balance.Three equations were compared,two alreadypublished and the equation that was adjusted in this work.The model was improved and validated with new variables and data.It is possible to estimate the fall and renew of leaves biomass in semideciduous forests with reasonable precision.展开更多
Biodiversity conservation denotes the protection, management and utilization of resources available on or below the surface of the earth. The sustainability of biodiversity resources rely on the ecological balance. A ...Biodiversity conservation denotes the protection, management and utilization of resources available on or below the surface of the earth. The sustainability of biodiversity resources rely on the ecological balance. A sound planning based on ecological background and human needs provide successful management of natural resources. The study area, Lumbini harbors rich biodiversity and provide significant habitats for several species of birds, mammals, herpetofauna and fish. There are four major habitat types in Lumbini area-farmland, forest, grassland and wetland. The resources outside the Lumbini Development Trust and surrounding villages have already depleted due to excessive human interference in natural resources. Lumbini and its vicinity are rich in natural resources but poor in terms of infrastructure and delivery of services. The areas are losing natural wealth to pay for development. Rural areas around Lumbini are confronted with worsening poverty, ill health, illiteracy and continuing deterioration of natural ecosystems on which the local residents depend for their well-being. The only way to assure a safer and more prosperous future in Lumbini area is to deal with environment and development issues in a balanced manner. This research work attested that the local stakeholders feel ownership on people centered conservation.展开更多
Organic agricultural systems rely on organic amendments to achieve crop fertility requirements, and weed control must be achieved without synthetic herbicides. Our objective was to determine the crop yield and soil qu...Organic agricultural systems rely on organic amendments to achieve crop fertility requirements, and weed control must be achieved without synthetic herbicides. Our objective was to determine the crop yield and soil quality as affected by a transition from grass to dryland organic agriculture in the Central Great Plains of North America. This study evaluated three beef feedlot compost(BFC)treatments in 2010–2015 following biennial application rates: 0(control), 22.9, and 108.7 t ha^(-1) on two dryland organic cropping systems: a wheat(Triticum aestivum)-fallow(WF) rotation harvested for grain and a triticale(Triticosecale)/pea(Pisum sativum)-fallow(T/P-F) rotation harvested for forage. The triticale + pea biomass responded positively to the 108.7-t ha^(-1) BFC treatment,but not the 22.9-t ha^(-1) BFC treatment. The wheat biomass was not affected by BFC addition, but biomass N content increased.Beef feedlot compost input did not increase wheat grain yields, but had a positive effect on wheat grain Zn content. Soil total C and N contents increased with the rate of 108.7 t ha^(-1) BFC after three applications, but not with 22.9 t ha^(-1) BFC. Soil enzyme activities associated with N and C cycling responded positively to the 108.7-t ha^(-1) BFC treatment. Saturated salts were high in the soil receiving 108.7 t ha^(-1) of BFC, but did not affect crop yields. These results showed that BFC was effective in enhancing forage yields, wheat grain quality, and soil C and N, as well as specific microbial enzymes important for nutrient cycling. However, the large rates of BFC necessary to elicit these positive responses did not increase grain yields, and resulted in an excessive buildup of soil P.展开更多
Saframycin A(SFM-A),a tetrahydroisoquinoline antibiotic isolated from Streptomyces lavendulae,shows potent anti-proliferation activities against a variety of tumor cell lines,and shares the core structure with ecteina...Saframycin A(SFM-A),a tetrahydroisoquinoline antibiotic isolated from Streptomyces lavendulae,shows potent anti-proliferation activities against a variety of tumor cell lines,and shares the core structure with ecteinascidin 743(ET-743),the anticancer drug for soft-tissue sarcoma.Characterization of the SFM-A biosynthetic gene cluster revealed three nonribosomal peptide synthetase genes and a series of genes encoding oxygenases.To investigate the function of sfmO2 gene,encoding a FAD-dependent monooxygenase/hydroxylase,we constructed the gene replacement mutant(△sfmO2) strain S.lavendulae TL2007 and the corresponding gene complementation mutant strain S.lavendulae TL2008.A novel compound,SFM-O,was isolated from the △sfmO2 replacement mutant strain and its structure was characterized by comparison to the HRMS and NMR spectra of SFM-A.These findings indicated that SfmO2 is responsible for the oxidation of ring A in the biosynthetic pathway of SFM-A,and the new compound SFM-O could be considered as an advanced intermediate in the semisynthesis of ET-743.展开更多
Phosphorus (P) is a major limiting factor for plant productivity in many ecosystems and agriculture. The projected increase in atmospheric CO2 is likely to result in changes in plant mineral consumption and growth. ...Phosphorus (P) is a major limiting factor for plant productivity in many ecosystems and agriculture. The projected increase in atmospheric CO2 is likely to result in changes in plant mineral consumption and growth. We studied P depletion by common bean (Phaseolus vulgaris) cultured hydroponically under ambient (377±77μmol mol^-1) or elevated (650±32 μmol mol^-1) CO2 in media of low or high P. Under elevated CO2 compared to ambient CO2, the maximum P depletion rate increased by 98% at low P and 250% at high P, and P was depleted about 2-5 weeks sooner; leaf acid phosphatase (APase) activity and chlorophyll content both increased significantly; root-to-shoot ratio increased significantly at high P, although it was unaffected at low P; lateral root respiration rate showed no change, suggesting that COs did not affect P depletion via metabolic changes to the roots; the total biomass at final harvest was significantly higher at both low and high P. Our data showed that the increased rate and amount of P depletion during plant growth under elevated CO2 occurred in association with alterations in leaf biochemical properties, i.e., enhanced activities of leaf APase and increased leaf chlorophyll content.展开更多
文摘Based on mass balance theory and IsoSource program,stable carbon and nitrogen isotopic ratios revealed that small mammals (plateau pika,root vole and plateau zokor) contributed 26.8% and 27.0% and 29.2% to alpine weasel,steppe polecat and upland buzzard of carnivores as food respectively;adult passerine birds contributed 22.3%,47.7% and 69.1%,with hatchlings contributing 50.9%,25.6% and 1.70% to each respectively.δ 13 C values plotted against δ 15 N indicated significant partitioning in two-dimensional space among the three carnivores.It was reasonable to propose a food resource partitioning among alpine weasel,steppe polecat and upland buzzard,which partially revealed their co-existence mechanisms.
基金funded by the National Science and Technology Support Project (Grant No.2014BAC05B01)National Program on Basic Work Project of China (Grant No.2015FY11030001)+1 种基金Strategic Priority Research Program of CAS (Grant No.XDA0505030304)National Natural Science Foundation of China (Grant No.40801076)
文摘Though aboveground biomass(AGB) has an important contribution to the global carbon cycle,the information about storage and climatic effects of AGB is scare in Three-River Source Region(TRSR)shrub ecosystems. This study investigated AGB storage and its climatic controls in the TRSR alpine shrub ecosystems using data collected from 23 sites on the Tibetan Plateau from 2011 to 2013. We estimated the AGB storage(both shrub layer biomass and grass layer biomass) in the alpine shrubs as 37.49 Tg, with an average density of 1447.31 g m^(-2). Biomass was primarily accumulated in the shrub layer, which accounted for 92% of AGB, while the grass layer accounted for only 8%. AGB significantly increased with the mean annual temperature(P < 0.05). The effects of the mean annual precipitation on AGB were not significant. These results suggest that temperature,rather than precipitation, has significantly effects on of aboveground vegetation growth in the TRSR alpine shrub ecosystems. The actual and potential increase in AGB density was different due to global warming varies among different regions of the TRSR. We conclude that long-term monitoring of dynamic changes is necessary to improve the accuracy estimations of potential AGB carbon sequestration across the TRSR alpine shrub ecosystems.
基金Supported by the National Natural Science Fund for Distinguished Young Scholars(21425625)the National Basic Research Program of China(2013CB733506,2015CB251403)+1 种基金the National Natural Science Foundation of China(U1610222)the Beijing Hundreds of Leading Talents Training Project of Science and Technology(Z171100001117154)
文摘This work addressed the multi-objective optimization of a biogas production system considering both environmental and economic criteria. A mixed integer non-linear programming(MINLP) model was established and solved with non-dominated sorting genetic algorithm Ⅱ, from which the Pareto fronts, the optimal technology combinations and operation conditions were obtained and analyzed. It's found that the system is feasible in both environmental and economic considerations after optimization. The most expensive processing section is decarbonization; the most expensive equipment is anaerobic digester; the most power-consuming processing section is digestion, followed by decarbonization and waste management. The positive green degree value on the process is attributed to processing section of digestion and waste management. 3:1 chicken feces and corn straw, solar energy, pressure swing adsorption and 3:1 chicken feces and rice straw, solar energy, pressure swing adsorption are turned out to be two robust technology combinations under different prices of methane and electricity by sensitivity analysis. The optimization results provide support for optimal design and operation of biogas production system considering environmental and economic objectives.
基金This item was supportedby the National ScienceFoundationof P.R.China (No.39330040,39460022)
文摘Evergreen broad-leaved forestis one of the most important vegetation types in China.Because of the human activities,evergreen broad-leaved forest has been destroyed extensively,leading to degraded ecosystem.It is urgent to conserve and restore these natural forests in China. In this paper,the tendency and rate of species diversity restoration of the evergreen broad-leaved forest in Daming Mountain has been studied.The main resultsare as follows:(a)In subtropical mid-mountain area,species diversity in degraded evergreen broad-leaved forestcan be restored. Through analyzing b diversity index of communities in different time and space,it was found that the species composition of communities tend to be the same as that in the zonal evergreen broad-leaved forest.(b)The restoration rate of evergreen broad-leaved forest was very fast.Planting Chinese fir after clear-cutting and controlled burning of the forest,178 species appeared in a 600m^2 sample area after 20 years’natural recovering.Among the sespecies,58 were tree layer and the height of community reached 18m.The survey suggested that it would take only 20 years for the degraded forest to develop into community composed of lightdemanding broad-leaved pioneer trees and min-tolerance broad-leaved trees,and it need another 40~80 years to reach the stage consisting of min-tolerance evergreen broad-leaved trees.(c)Species number increased quickly at the early stage(2-20years)during vegetation recovering process toward the climax,and decreased at the min-stage (50-60 years),then maintained a relatively stable level at the late-stage (over 150 years).
基金Supported by the National Natural Science Foundation of China(Nos.41471088,41301077)
文摘Allochthonous organic matter plays an important role in nutrient cycling and energy mobilization in freshwater ecosystems. However, the subsidies of this carbon source in floodplain ecosystems have not yet well understood. We used a Bayesian mixing model and stable isotopes (613C and 815N) of primary food resources and dominant molluscs species, to estimate the relative importance of allochthonous carbon sources for consumers in a representative sub-lake of Poyang Lake during a prolonged dry season. Our study inferred that terrestrial-derived carbon from Carex spp. could be the primary contributor to snails and mussels in Dahuchi Lake. The mean percentage of allochthonous food resources accounted for 35%- 50% of the C incorporated by these consumers. Seston was another important energy sources for benthic consumers. However, during the winter and low water-level period, benthic algae and submerged vegetation contributed less carbon to benthic consumers. Our data highlighted the importance of terrestrial organic carbon to benthic consumers in the wetlands of Poyang Lake during the prolonged dry period. Further, our results provided a perspective that linkages between terrestrial and aquatic ecosystems might be facilitated by wintering geese via their droppings.
基金Under the auspices of Major State Basic Research Development Program of China(No.2009CB421100,2010CB950900)
文摘By using field survey data from the sixth forest inventory of Jiangxi Province in 2003,the biomass and carbon storage for three studied species(Pinus massoniana,Cunninghamia lanceolata,and Pinus elliottii)were estimated in Taihe and Xingguo counties of Boyang Lake Basin,Jiangxi Province,China.The relationship between carbon density and forest age was analyzed by logistic equations.Spatio-temporal dynamics of forest biomass and carbon storage in 1985–2003 were also described.The results show that total stand area of the three forest species was 3.10×105ha,total biomass 22.20 Tg,vegetation carbon storage 13.07 Tg C,and average carbon density 42.36 Mg C/ha in the study area in 2003.Carbon storage by forest type in descending order was:P.massoniana,C.lanceolata and P.elliottii.Carbon storage by forest age group in descending order was:middle stand,young stand,near-mature stand and mature stand.Carbon storage by plantation forests was 1.89 times higher than that by natural forests.Carbon density of the three species increased 8.58 Mg C/ha during the study period.The carbon density of Taihe County was higher in the east and west,and lower in the middle.The carbon density of Xingguo County was higher in the northeast and lower in the middle.In general,the carbon density increased with altitude and gradient.Afforestation projects contribute significantly to increasing stand area and carbon storage.Appropriate forest management may improve the carbon sequestration capacity of forest ecosystems.
文摘Puget Sound shorelines have historically provided a diversity of habitats that support a variety of aquatic resources throughout the area. These valued natural resources are iconic to the region and remain central to both the economic vitality and community appreciation of Puget Sound. Coastal developments over the past 30 years have placed increased pressure on aquatic resources through deterioration of upland and nearshore shoreline habitats within the region. Since a majority of Washington State upland shorelines are privately owned, regulatory authority to require future restoration on private property is not feasible. Washington States' Shoreline Management Act requires local jurisdictions to plan for appropriate future shoreline uses. Under the Act, future development can be regulated to protect existing ecological functions. However, lost functions cannot be retroactively restored through regulatory means, but rather require purchase or compensation of the private property to be restored. Therefore, questions remain as to the ecological resilience of the region when considering cumulative effects of existing and ongoing shoreline development and limited shoreline restoration opportunities constrained to public lands. In light of these questions, this analysis will explore opportunities to promote restoration on privately owned shorelines within Puget Sound. These efforts are intended to promote more efficient coastal management to improve ecosystem services.
文摘The large reserves ofoil are disposed in zones of permafrost in shelf and continental fields. In Europe the subarctic and arctic tundra are abundant only in Nenetsky autonomous area and in the north-east of the republic of Komi. Oil and gas production activity has threatened richest biological resources and health of the population of the region. A singularity of petroliferous fields of the north of Russia is the existence of the thick strata of permafrost. On top of them different heat-insulating overlying layers (snow, biogenic covers) reside. State and dynamics of permafrost cause progressing dangerous exogenic geoecological processes, which are exhibited completely. State of permafrost is instituted by exchange of heat in near-surface strata of a geological section. During the development of oil fields there is a disturbance of a temperature schedule of permafrost. For estimation of technical attack the analytical computational method of influence of the different factors on value of annual heat exchange and prediction of geocryological conditions is proposed. It is shown, that such dangerous phenomena as degradation of permafrost and thermokarst would develop in the first place, which would cause the destruction of natural ecosystems.
文摘The climate,mainly the water availability and temperature,drives the renewal of biomass inseasonal forest ecosystem,and the greenness and leaf area of its canopy are responsive climate variations.This study verified models to explain the phenomenon of leaf production and deciduousness by time,with LAI(Leaf Area Index),NDVI(Normalized Difference VegetationIndex)and climate variables,on period 2011-2016. The data were obtained in satellite images and in plots installed at forestmonitoring sites,visited monthly.The analysis incorporated the water balance.Three equations were compared,two alreadypublished and the equation that was adjusted in this work.The model was improved and validated with new variables and data.It is possible to estimate the fall and renew of leaves biomass in semideciduous forests with reasonable precision.
文摘Biodiversity conservation denotes the protection, management and utilization of resources available on or below the surface of the earth. The sustainability of biodiversity resources rely on the ecological balance. A sound planning based on ecological background and human needs provide successful management of natural resources. The study area, Lumbini harbors rich biodiversity and provide significant habitats for several species of birds, mammals, herpetofauna and fish. There are four major habitat types in Lumbini area-farmland, forest, grassland and wetland. The resources outside the Lumbini Development Trust and surrounding villages have already depleted due to excessive human interference in natural resources. Lumbini and its vicinity are rich in natural resources but poor in terms of infrastructure and delivery of services. The areas are losing natural wealth to pay for development. Rural areas around Lumbini are confronted with worsening poverty, ill health, illiteracy and continuing deterioration of natural ecosystems on which the local residents depend for their well-being. The only way to assure a safer and more prosperous future in Lumbini area is to deal with environment and development issues in a balanced manner. This research work attested that the local stakeholders feel ownership on people centered conservation.
文摘Organic agricultural systems rely on organic amendments to achieve crop fertility requirements, and weed control must be achieved without synthetic herbicides. Our objective was to determine the crop yield and soil quality as affected by a transition from grass to dryland organic agriculture in the Central Great Plains of North America. This study evaluated three beef feedlot compost(BFC)treatments in 2010–2015 following biennial application rates: 0(control), 22.9, and 108.7 t ha^(-1) on two dryland organic cropping systems: a wheat(Triticum aestivum)-fallow(WF) rotation harvested for grain and a triticale(Triticosecale)/pea(Pisum sativum)-fallow(T/P-F) rotation harvested for forage. The triticale + pea biomass responded positively to the 108.7-t ha^(-1) BFC treatment,but not the 22.9-t ha^(-1) BFC treatment. The wheat biomass was not affected by BFC addition, but biomass N content increased.Beef feedlot compost input did not increase wheat grain yields, but had a positive effect on wheat grain Zn content. Soil total C and N contents increased with the rate of 108.7 t ha^(-1) BFC after three applications, but not with 22.9 t ha^(-1) BFC. Soil enzyme activities associated with N and C cycling responded positively to the 108.7-t ha^(-1) BFC treatment. Saturated salts were high in the soil receiving 108.7 t ha^(-1) of BFC, but did not affect crop yields. These results showed that BFC was effective in enhancing forage yields, wheat grain quality, and soil C and N, as well as specific microbial enzymes important for nutrient cycling. However, the large rates of BFC necessary to elicit these positive responses did not increase grain yields, and resulted in an excessive buildup of soil P.
基金supported in part by grants from the National Natural Science Foundation of China(20832009,and 20921091)the Chinese Academy of Sciences and Open Funding Project of the State Key Laboratory of Bioreactor Engineering
文摘Saframycin A(SFM-A),a tetrahydroisoquinoline antibiotic isolated from Streptomyces lavendulae,shows potent anti-proliferation activities against a variety of tumor cell lines,and shares the core structure with ecteinascidin 743(ET-743),the anticancer drug for soft-tissue sarcoma.Characterization of the SFM-A biosynthetic gene cluster revealed three nonribosomal peptide synthetase genes and a series of genes encoding oxygenases.To investigate the function of sfmO2 gene,encoding a FAD-dependent monooxygenase/hydroxylase,we constructed the gene replacement mutant(△sfmO2) strain S.lavendulae TL2007 and the corresponding gene complementation mutant strain S.lavendulae TL2008.A novel compound,SFM-O,was isolated from the △sfmO2 replacement mutant strain and its structure was characterized by comparison to the HRMS and NMR spectra of SFM-A.These findings indicated that SfmO2 is responsible for the oxidation of ring A in the biosynthetic pathway of SFM-A,and the new compound SFM-O could be considered as an advanced intermediate in the semisynthesis of ET-743.
基金supported by the Truman State University Math Bio Programthe National Science Foundation, USA (Nos. 0436348 and 0337769)
文摘Phosphorus (P) is a major limiting factor for plant productivity in many ecosystems and agriculture. The projected increase in atmospheric CO2 is likely to result in changes in plant mineral consumption and growth. We studied P depletion by common bean (Phaseolus vulgaris) cultured hydroponically under ambient (377±77μmol mol^-1) or elevated (650±32 μmol mol^-1) CO2 in media of low or high P. Under elevated CO2 compared to ambient CO2, the maximum P depletion rate increased by 98% at low P and 250% at high P, and P was depleted about 2-5 weeks sooner; leaf acid phosphatase (APase) activity and chlorophyll content both increased significantly; root-to-shoot ratio increased significantly at high P, although it was unaffected at low P; lateral root respiration rate showed no change, suggesting that COs did not affect P depletion via metabolic changes to the roots; the total biomass at final harvest was significantly higher at both low and high P. Our data showed that the increased rate and amount of P depletion during plant growth under elevated CO2 occurred in association with alterations in leaf biochemical properties, i.e., enhanced activities of leaf APase and increased leaf chlorophyll content.