Key issues of concern regarding the environmental impacts of livestock on grazing land are their effects on soil, water quality, and biodiversity. This study was carried out to determine how grazing intensity influenc...Key issues of concern regarding the environmental impacts of livestock on grazing land are their effects on soil, water quality, and biodiversity. This study was carried out to determine how grazing intensity influences soil physical and chemical properties and occurrence of herbaceous plant species in dambo wetlands. Three categories of grazing intensity were selected from communal, small scale commercial and large scale commercial land. Dambos from the large scale commercial land functioned as the control. Data analysis included ANOVA and multivariate tests from CANOCO. There were significantly negative changes to soil nutrient status in communal dambos though with a higher number of rare taxa. Sodium, phosphorous, pH and infiltration rate were significant determinants of plant species occurrence. Overgrazing is threatening the productivity, stability, and ecological functioning of dambo soils in communal Zimbabwe. These dambos also require special conservation and management priorities as they contain a large number of rare plant species.展开更多
Anzali International wetland is located in the south coast of the Caspian Sea. Physicochemical analysis and zooplankton survey of the wetland were carried out on monthly basis for the period of one year from January 2...Anzali International wetland is located in the south coast of the Caspian Sea. Physicochemical analysis and zooplankton survey of the wetland were carried out on monthly basis for the period of one year from January 2012 to December 2013 at 9 different stations of Anzali wetland and its related channel to the Caspian Sea. Water temperature of the wetland followed more or less similar trend as that of air temperature. pH determined alkaline nature of the wetland ranging between 7.05 to 9.47, dissolved oxygen was recorded in the range of 3.36 mg/l to 10.51 mg/l while other parameters recorded were water temperature (10 to 23 C), Nitrate (0.48 to 4.36 mg/l), Total Phosphates (0.15 to 0.67 mg/l), Salinity (220 to 692 mg/l), Electrical Conductivity (235 to 1369 μs/cm), TDS (246 to 1971 mg/l), BOD (2 to 36 mg/l) and COD (4 to 74 mg/l). During study period, total 60 species of zooplankton were identified in four main groups such as Protozoa (22 sp.), Rotifera (29 sp.), Copepoda (5 sp.) and Cladocera (4 sp.). The highest numbers of zooplankton were recorded in summer months and lowest in winter which is the second rainy season of this area. The water body is receiving domestic discharge, agricultural run-off and industrial wastes leading to large amount of nutrient inputs to the ecosystem which indicates the eutrophic statue of the wetland. The aim of present study was to investigate the interrelationship between physicochemical factors and zooplankton population in context of their seasonal abundance.展开更多
To investigate the spatio-temporal and compositional variation of selected water quality parameters and understand the puri- fying effects of wetland in Fujin National Wetland Park （FNWP）, China, the trophic level i...To investigate the spatio-temporal and compositional variation of selected water quality parameters and understand the puri- fying effects of wetland in Fujin National Wetland Park （FNWP）, China, the trophic level index （TLI）, paired samples t-test and correla- tion analysis were used for the statistical analysis of a set of 10 water quality parameters. The analyses were based on water samples collected from 22 stations in FNWP between 2014 and 2016. Results initially reveal that total nitrogen （TN） concentrations are above class V levels （2 mg/L）, total phosphorus （TP） concentrations are below class III levels （0.2 mg/L）, and that all other parameters fall within standard ranges. Highest values for TN, pH, and Chlorophyll-a were recorded in 2016, while the levels of chemical oxygen de- mand （CODMn） and biochemical oxygen demand （BODs） were lowest during this year. Similarly, TN values were highest between 2014 and 2016 while dissolved oxygen （DO） concentrations were lowest in the summer and TP concentrations were highest in the autumn. Significant variations were also found in Secchi depth （SD）, TN, CODMn （P 〈 0.01）, TP, and DO levels （P 〈 0.05） between the inlet and outlet of the park. High-to-low levels of TN, TP, and TDS were found in cattails, reeds, and open water （the opposite trend was seen in SD levels）. Tested wetland water had a light eutrophication status in most cases and TN and TP removal rates were between 7.54%-84.36% and 37.50%-70.83%, respectively. Data also show no significant annual changes in water quality within this wetland, although obvious affects from surrounding agricultural drainage were nevertheless recorded. Results reveal a high major nutrient removal efficiency （N and P）. The upper limits of these phenomena should be addressed in future research alongside a more efficient and scientific agricultural layout for the regions in and around the FNWP.展开更多
This study explores the effects of vegetation and season on soil microorganisms and enzymatic activity of different wetlands in a temperate climate.Microbial carbon metabolism diversity was assessed using community-le...This study explores the effects of vegetation and season on soil microorganisms and enzymatic activity of different wetlands in a temperate climate.Microbial carbon metabolism diversity was assessed using community-level physiological profiles(CLPP)with 31 different carbon substrates.CLPP indicated that significant interactions occur during carbon substrate metabolism of the microorganisms.Furthermore,the different types of vegetation present in the wetland ecosystem combined with the seasonal effects to influence microbial carbon metabolism and enzymatic activity.The most significant differences occurred to carbohydrates,carboxylic acids,and amino acids.The Mantel test confirmed positive correlations between soil enzymatic activities and microbial carbon metabolism.Soil microorganisms in Betula ovalifolia and Carex schmidtii wetlands used carbon substrates more efficiently in summer than those in other forested wetlands during other periods.Enzymatic activities also showed a similar trend as microbial carbon metabolism.The results demonstrate that microbial carbon metabolism patterns can be used as biological indicators in wetland ecological alterations due to vegetation type or to seasonal factors.展开更多
From studies undertaken during 1995-2004, annual budgets of CH4 emissions from natural wetlands and its temporal and spatial variations were examined throughout China, and various factors influencing CH4 emissions wer...From studies undertaken during 1995-2004, annual budgets of CH4 emissions from natural wetlands and its temporal and spatial variations were examined throughout China, and various factors influencing CH4 emissions were also evaluated. The seasonal variation in CH4 emissions that increased with increasing plant growth reached its peak in August; decrease in the emissions was found in freshwater marshes but not in peatlands. Emissions were mainly controlled by temperature and depth of standing water. Low CH4 emissions at the early plant growing stages were not because of deficiency of organic C for CH4 production but because of low temperatures. Low temperatures not only reduced CH4 production but also stimulated CH4 oxidation by lowering the activity of other aerobic microbes which left more 02 in the rhizosphere for methanotrophs. Low summer temperatures （below 20 ℃） in the Qinghai-Tibetan Plateau lowered CH4 production and CH4 emission resulting in little or no seasonal variation of emissions. Diel and spatial variation in CH4 emissions depended on plant species. For plants that transport CH4 using the pressure-driven convective through-flow mechanism, diel variation in CH4 emissions was governed by diel variation of solar energy load （that produces temperature and vapor pressure differences within various plant tissues） and stomatal conductance. For plants that transport gases using the molecular diffusion mechanism only, the diel variation of CH4 emissions was because of differences in the magnitude of O2 produced through photosynthesis and then delivered into the rhizomes and/or rhizosphere for CH4 oxidation. Emergent plants could transport more CH4 than submerged plants because the former transport CH4 directly into the atmosphere rather than into water as do submerged plants where CH4 can be further be oxidized during its diffusion from water to the atmosphere. Emergent plants with high gas transport capacity could not only transport more CH4 into the atmosphere but also live in deeper water, which in turn would inundate more plant litter, resulting in increased availability of C for CH4 production. Annual CH4 emission from natural wetlands in China was estimated to be 1.76 Tg, up to 1.17 Tg of which was emitted from freshwater marshes. CH4 emission from freshwater marshes mainly occurred during the growing season and less than 8% was released during the freeze-thawing period despite the fact that thawing efficiently released CH4 fixed in ice column into the atmosphere.展开更多
Agriculture is one of the biggest sources of greenhouse gases. Rice production has been identified as one of the major sources of greenhouse gases, especially methane. However, data on the contributions of rice toward...Agriculture is one of the biggest sources of greenhouse gases. Rice production has been identified as one of the major sources of greenhouse gases, especially methane. However, data on the contributions of rice towards greenhouse gas emissions in tropical Africa are limited. In Zimbabwe, as in most of Sub-Saharan Africa, there are very few studies that have explored greenhouse gas emissions from agricultural lands. This study reports the first dataset on greenhouse gas emissions from intermittently flooded rice paddies in Zimbabwe. The objective of this study was to quantify greenhouse gas emissions from dambo rice under different tillage treatments, which were conventional tillage, no tillage, tied ridges, tied fallows, and mulching. Average soil nitrous oxide emissions were 5.9, 0.2, 5.4, 5.2 and 7.8 μg·m-2·hr-1 for tied fallows, conventional tillage, tied ridges, mulching and no tillage respectively. Average methane emission was 0.35 mg·m-2·hr-1 and maximum as 1.62 mg·m-2·hr-1. Average methane emissions for the different tillage systems were 0.20, 0.18, 0.45, 0.52 and 0.38 mg·m-2·hr-1 for tied fallows, conventional tillage, tied ridges, mulching and no tillage respectively. Carbon dioxide emissions were 98.1, 56.0, 69.9, 94.8 and 95.5 mg·m-2·hr-1 for tied fallows, conventional tillage, tied ridges, mulching and no tillage respectively. The estimated emissions per 150 day cropping season were 1.4, 3.6 and 0.6 kg·ha-1 for methane, carbon dioxide and nitrous oxide respectively. We concluded that intermittently saturated dambo rice Paddys are a potential source of greenhouse gases which is important to global greenhouse gas budgets, thus, they deserve more careful study.展开更多
Algae are one of the major groups of soil microflora in agricultural lands. Among algae, the bluegreens are considered to be very valuable in agriculture. The role of them in soil fertility enhancement has been extens...Algae are one of the major groups of soil microflora in agricultural lands. Among algae, the bluegreens are considered to be very valuable in agriculture. The role of them in soil fertility enhancement has been extensively studied worldwide. Sustainable utilization of an organism for any human purpose depends on how successfully the ecology of the same is thoroughly understood. Kuttanadu is a unique tropical paddy-wetland. Ecology of blue-green-algae and the exact diversity of the same in the zone remained unexplored. This is the first report of the blue-green-algal community of Kuttanadu in relation to different soil-regions, seasons, and crop-growth-stages. A rich blue-green-algal diversity of 64 species, with Oscillatoriales as the dominants (38%), is observed in these paddy-fields. The highest values for all the ecological parameters analyzed were found in the Lower Kuttanadu soil region, during Virippu season, at panicle stage of the crop whereas the lowest values for most of the parameters were observed in Upper Kuttanadu soils during puncha season at the seedling and panicle stages. The species richness and diversity index showed positive correlation to crop seasons. Apart from the specific soil and climatic factors, the total number of blue green algal isolates showed positive correlation to total nitrogen and phosphorus in the soils.展开更多
文摘Key issues of concern regarding the environmental impacts of livestock on grazing land are their effects on soil, water quality, and biodiversity. This study was carried out to determine how grazing intensity influences soil physical and chemical properties and occurrence of herbaceous plant species in dambo wetlands. Three categories of grazing intensity were selected from communal, small scale commercial and large scale commercial land. Dambos from the large scale commercial land functioned as the control. Data analysis included ANOVA and multivariate tests from CANOCO. There were significantly negative changes to soil nutrient status in communal dambos though with a higher number of rare taxa. Sodium, phosphorous, pH and infiltration rate were significant determinants of plant species occurrence. Overgrazing is threatening the productivity, stability, and ecological functioning of dambo soils in communal Zimbabwe. These dambos also require special conservation and management priorities as they contain a large number of rare plant species.
文摘Anzali International wetland is located in the south coast of the Caspian Sea. Physicochemical analysis and zooplankton survey of the wetland were carried out on monthly basis for the period of one year from January 2012 to December 2013 at 9 different stations of Anzali wetland and its related channel to the Caspian Sea. Water temperature of the wetland followed more or less similar trend as that of air temperature. pH determined alkaline nature of the wetland ranging between 7.05 to 9.47, dissolved oxygen was recorded in the range of 3.36 mg/l to 10.51 mg/l while other parameters recorded were water temperature (10 to 23 C), Nitrate (0.48 to 4.36 mg/l), Total Phosphates (0.15 to 0.67 mg/l), Salinity (220 to 692 mg/l), Electrical Conductivity (235 to 1369 μs/cm), TDS (246 to 1971 mg/l), BOD (2 to 36 mg/l) and COD (4 to 74 mg/l). During study period, total 60 species of zooplankton were identified in four main groups such as Protozoa (22 sp.), Rotifera (29 sp.), Copepoda (5 sp.) and Cladocera (4 sp.). The highest numbers of zooplankton were recorded in summer months and lowest in winter which is the second rainy season of this area. The water body is receiving domestic discharge, agricultural run-off and industrial wastes leading to large amount of nutrient inputs to the ecosystem which indicates the eutrophic statue of the wetland. The aim of present study was to investigate the interrelationship between physicochemical factors and zooplankton population in context of their seasonal abundance.
基金Under the auspices of the National Natural Science Foundation of China(No.D41271106)the National Key Research and Development Program of China(No.2016YFA0602303)
文摘To investigate the spatio-temporal and compositional variation of selected water quality parameters and understand the puri- fying effects of wetland in Fujin National Wetland Park （FNWP）, China, the trophic level index （TLI）, paired samples t-test and correla- tion analysis were used for the statistical analysis of a set of 10 water quality parameters. The analyses were based on water samples collected from 22 stations in FNWP between 2014 and 2016. Results initially reveal that total nitrogen （TN） concentrations are above class V levels （2 mg/L）, total phosphorus （TP） concentrations are below class III levels （0.2 mg/L）, and that all other parameters fall within standard ranges. Highest values for TN, pH, and Chlorophyll-a were recorded in 2016, while the levels of chemical oxygen de- mand （CODMn） and biochemical oxygen demand （BODs） were lowest during this year. Similarly, TN values were highest between 2014 and 2016 while dissolved oxygen （DO） concentrations were lowest in the summer and TP concentrations were highest in the autumn. Significant variations were also found in Secchi depth （SD）, TN, CODMn （P 〈 0.01）, TP, and DO levels （P 〈 0.05） between the inlet and outlet of the park. High-to-low levels of TN, TP, and TDS were found in cattails, reeds, and open water （the opposite trend was seen in SD levels）. Tested wetland water had a light eutrophication status in most cases and TN and TP removal rates were between 7.54%-84.36% and 37.50%-70.83%, respectively. Data also show no significant annual changes in water quality within this wetland, although obvious affects from surrounding agricultural drainage were nevertheless recorded. Results reveal a high major nutrient removal efficiency （N and P）. The upper limits of these phenomena should be addressed in future research alongside a more efficient and scientific agricultural layout for the regions in and around the FNWP.
基金The work was supported by the National Natural Science Foundation of China(No.31500508)the Fundamental Research Funds for the Central Universities(No.2572020BD02)Natural Science Foundation of Heilongjiang Province(No.LH2020C041).
文摘This study explores the effects of vegetation and season on soil microorganisms and enzymatic activity of different wetlands in a temperate climate.Microbial carbon metabolism diversity was assessed using community-level physiological profiles(CLPP)with 31 different carbon substrates.CLPP indicated that significant interactions occur during carbon substrate metabolism of the microorganisms.Furthermore,the different types of vegetation present in the wetland ecosystem combined with the seasonal effects to influence microbial carbon metabolism and enzymatic activity.The most significant differences occurred to carbohydrates,carboxylic acids,and amino acids.The Mantel test confirmed positive correlations between soil enzymatic activities and microbial carbon metabolism.Soil microorganisms in Betula ovalifolia and Carex schmidtii wetlands used carbon substrates more efficiently in summer than those in other forested wetlands during other periods.Enzymatic activities also showed a similar trend as microbial carbon metabolism.The results demonstrate that microbial carbon metabolism patterns can be used as biological indicators in wetland ecological alterations due to vegetation type or to seasonal factors.
基金the National Natural Science Foundation of China (No.40471121)the Field Station Foundation of the Chinese Academy,of Sciences.
文摘From studies undertaken during 1995-2004, annual budgets of CH4 emissions from natural wetlands and its temporal and spatial variations were examined throughout China, and various factors influencing CH4 emissions were also evaluated. The seasonal variation in CH4 emissions that increased with increasing plant growth reached its peak in August; decrease in the emissions was found in freshwater marshes but not in peatlands. Emissions were mainly controlled by temperature and depth of standing water. Low CH4 emissions at the early plant growing stages were not because of deficiency of organic C for CH4 production but because of low temperatures. Low temperatures not only reduced CH4 production but also stimulated CH4 oxidation by lowering the activity of other aerobic microbes which left more 02 in the rhizosphere for methanotrophs. Low summer temperatures （below 20 ℃） in the Qinghai-Tibetan Plateau lowered CH4 production and CH4 emission resulting in little or no seasonal variation of emissions. Diel and spatial variation in CH4 emissions depended on plant species. For plants that transport CH4 using the pressure-driven convective through-flow mechanism, diel variation in CH4 emissions was governed by diel variation of solar energy load （that produces temperature and vapor pressure differences within various plant tissues） and stomatal conductance. For plants that transport gases using the molecular diffusion mechanism only, the diel variation of CH4 emissions was because of differences in the magnitude of O2 produced through photosynthesis and then delivered into the rhizomes and/or rhizosphere for CH4 oxidation. Emergent plants could transport more CH4 than submerged plants because the former transport CH4 directly into the atmosphere rather than into water as do submerged plants where CH4 can be further be oxidized during its diffusion from water to the atmosphere. Emergent plants with high gas transport capacity could not only transport more CH4 into the atmosphere but also live in deeper water, which in turn would inundate more plant litter, resulting in increased availability of C for CH4 production. Annual CH4 emission from natural wetlands in China was estimated to be 1.76 Tg, up to 1.17 Tg of which was emitted from freshwater marshes. CH4 emission from freshwater marshes mainly occurred during the growing season and less than 8% was released during the freeze-thawing period despite the fact that thawing efficiently released CH4 fixed in ice column into the atmosphere.
文摘Agriculture is one of the biggest sources of greenhouse gases. Rice production has been identified as one of the major sources of greenhouse gases, especially methane. However, data on the contributions of rice towards greenhouse gas emissions in tropical Africa are limited. In Zimbabwe, as in most of Sub-Saharan Africa, there are very few studies that have explored greenhouse gas emissions from agricultural lands. This study reports the first dataset on greenhouse gas emissions from intermittently flooded rice paddies in Zimbabwe. The objective of this study was to quantify greenhouse gas emissions from dambo rice under different tillage treatments, which were conventional tillage, no tillage, tied ridges, tied fallows, and mulching. Average soil nitrous oxide emissions were 5.9, 0.2, 5.4, 5.2 and 7.8 μg·m-2·hr-1 for tied fallows, conventional tillage, tied ridges, mulching and no tillage respectively. Average methane emission was 0.35 mg·m-2·hr-1 and maximum as 1.62 mg·m-2·hr-1. Average methane emissions for the different tillage systems were 0.20, 0.18, 0.45, 0.52 and 0.38 mg·m-2·hr-1 for tied fallows, conventional tillage, tied ridges, mulching and no tillage respectively. Carbon dioxide emissions were 98.1, 56.0, 69.9, 94.8 and 95.5 mg·m-2·hr-1 for tied fallows, conventional tillage, tied ridges, mulching and no tillage respectively. The estimated emissions per 150 day cropping season were 1.4, 3.6 and 0.6 kg·ha-1 for methane, carbon dioxide and nitrous oxide respectively. We concluded that intermittently saturated dambo rice Paddys are a potential source of greenhouse gases which is important to global greenhouse gas budgets, thus, they deserve more careful study.
文摘Algae are one of the major groups of soil microflora in agricultural lands. Among algae, the bluegreens are considered to be very valuable in agriculture. The role of them in soil fertility enhancement has been extensively studied worldwide. Sustainable utilization of an organism for any human purpose depends on how successfully the ecology of the same is thoroughly understood. Kuttanadu is a unique tropical paddy-wetland. Ecology of blue-green-algae and the exact diversity of the same in the zone remained unexplored. This is the first report of the blue-green-algal community of Kuttanadu in relation to different soil-regions, seasons, and crop-growth-stages. A rich blue-green-algal diversity of 64 species, with Oscillatoriales as the dominants (38%), is observed in these paddy-fields. The highest values for all the ecological parameters analyzed were found in the Lower Kuttanadu soil region, during Virippu season, at panicle stage of the crop whereas the lowest values for most of the parameters were observed in Upper Kuttanadu soils during puncha season at the seedling and panicle stages. The species richness and diversity index showed positive correlation to crop seasons. Apart from the specific soil and climatic factors, the total number of blue green algal isolates showed positive correlation to total nitrogen and phosphorus in the soils.
