Accurate capture and presentation of the interactive feedback relationships among various objectives in multi-objective reservoir operation is essential for maximizing operational benefits.In this study,the niche theo...Accurate capture and presentation of the interactive feedback relationships among various objectives in multi-objective reservoir operation is essential for maximizing operational benefits.In this study,the niche theory of ecology was innovatively applied to the field of reservoir operation,and a novel state-relationship(S-R)measurement analysis method was developed for multi-objective reservoir operation.This method enables the study of interaction among multiple objectives.This method was used to investigate the relationship among the objectives of power generation,water supply,and ecological protection for cascade reservoir operation in the Wujiang River Basin in China.The results indicated that the ecological protection objective was the most competitive in acquiring and capturing resources like flow and water level,while the water supply objective was the weakest.Power generation competed most strongly with ecological protection and relatively weakly with water supply.These findings facilitate decision-making throughout the reservoir operation process in the region.The S-R method based on the niche theory is convenient,efficient,and intuitive,allowing for the quantification of feedback relationships among objectives without requiring the solution of the Pareto frontier of a multi-objective problem in advance.This method provides a novel and feasible idea for studying multi-objective interactions.展开更多
Besides obvious benefits,the Three Gorges Dam＇s construction resulted in new pollution scenarios with the potentials to threaten the Three Gorges Reservoir（TGR） ecosystem.In order to record organic contamination,to...Besides obvious benefits,the Three Gorges Dam＇s construction resulted in new pollution scenarios with the potentials to threaten the Three Gorges Reservoir（TGR） ecosystem.In order to record organic contamination,to find links to ecotoxicological impacts and to serve as reference for ensuing monitoring,several sites in the TGR area were screened applying the triad approach with additional lines-of-evidence as a holistic assessment method.Sediments and the benthic fish species Pelteobagrus vachellii were sampled in 2011 and 2012 to determine organic pollution levels,mutagenic potentials and genotoxic impacts.Two regional hot-spots near the cities of Chongqing and Kaixian were identified and further investigated in 2013.Only polycyclic aromatic hydrocarbons（PAHs） could be detected in sediments in 2011（165-1653 ng/g）,emphasizing their roles as key pollutants of the area.Their ubiquity was confirmed at Chongqing（150-433 ng/g） and Kaixian（127-590 ng/g） in2013.Concentrations were comparable to other major Chinese and German rivers.However,the immense sediment influx suggested a deposition of 216-636 kg PAH/day（0.2-0.6 mg PAH/（m2·day））,indicating an ecotoxicological risk.PAH source analysis highlighted primary impacts of combustion sources on the more industrialized upper TGR section,whereas petrogenic sources dominated the mid-low section.Furthermore,sediment extracts from several sites exhibited significant activities of frameshift promutagens in the Ames fluctuation assay.Additionally,significant genotoxic impairments in erythrocytes of P.vachellii were detected（Chongqing/Kaixian）,demonstrating the relevance of genotoxicity as animportant mode of action in the TGR＇s fish.PAHs,their derivatives and non-target compounds are considered as main causative agents.展开更多
It is globally accepted that soil carbon （C） dynamics are at the core of interlinked environmental problems, deteriorating soil quality and changing climate. Its management remains a complex enigma for the scientifi...It is globally accepted that soil carbon （C） dynamics are at the core of interlinked environmental problems, deteriorating soil quality and changing climate. Its management remains a complex enigma for the scientific community due to its intricate relationship with soil nitrogen （N） availability and moisture-temperature interactions. This article reviews the management aspects of soil C dynamics in light of recent advances, particularly in relation to the availability of inorganic N pools and associated microbial processes under changing climate. Globally, drastic alterations in soil C dynamics under changing land use and management practices have been primarily attributed to the variation in soil N availability, resulting in a higher decomposition rate and a considerable decline in soil organic C （SOC） levels due to increased soil CO2 emissions, degraded soil quality, and increased atmospheric CO2 concentrations, leading to climate warming. Predicted climate warming is proposed to enhance SOC decomposition, which may further increase soil N availability, leading to higher soil CO2 effiux. However, a literature survey revealed that soil may also act as a potential C sink, if we could manage soil inorganic N pools and link microbial processes properly. Studies also indicated that the relative, rather than the absolute, availability of inorganic N pools might be of key importance under changing climate, as these N pools are variably affected by moisture-temperature interactions, and they have variable impacts on SOC turnover. Therefore, multi-factorial studies are required to understand how the relative availability of inorganic N pools and associated microbial processes may determine SOC dynamics for improved soil C management.展开更多
To understand the reason for the success of weeds,we investigated the energetic cost of leaf construction,and certain ecophysiological traits of rice and its dominant weeds.On physiological basis among all weeds,Caesu...To understand the reason for the success of weeds,we investigated the energetic cost of leaf construction,and certain ecophysiological traits of rice and its dominant weeds.On physiological basis among all weeds,Caesulia axillaris Roxburgh was found to be the most serious,followed by Echinochloa cruss-galli L.Beauv and Echinochloa colonum L.Link,while Fimbristylis miliaceae L.Vahl and Cyperus iria L.were moderate weeds of the rice fields.C.axillaris had the lowest leaf construction cost （LCC） both on a mass basis （1.15 g/g） and on a unit area basis （22.93 g/m2）.Comparatively higher specific leaf area,photosynthetic rate,photosynthetic nitrogen use efficiency,leaf area ratio and leaf area index provided C.axillaris with further competitive advantage.Low LCC suggests that weeds utilize carbon resource more efficiently than the crop and potentially spend the saved energy on other competitive strategies viz.seed production,biomass production and high relative growth rate,which results in low crop yield and increase in weed seed bank.展开更多
The objective of this paper is to institute farmers’ own perceptions of the on-and off-farm benefits of agroforestry systems (AFS). Using use value approach, this paper presents empirical evidence on the use values o...The objective of this paper is to institute farmers’ own perceptions of the on-and off-farm benefits of agroforestry systems (AFS). Using use value approach, this paper presents empirical evidence on the use values of three types of AFS practiced by the refugees and their hosting communities in Eastern Sudan. The total economic value (TEV) was applied as a framework to estimate the ecosystem values of AFS under study. Goods values were estimated using specific market values, while the services values were qualitatively described according to local perceived values of the local communities. Perceived TEV of AFS includes marketable and non-marketable goods and services. The main direct marketable and sustainable high value products include: food, cash crops, firewood, gum, fodder, NTFPs medicine, fodder, and honey. The valuation results reveal that AFS in the project sites have significantly contributed to the livelihoods of the local communities. Overall, the average net direct-use value of marketable products across all sites was estimated at 7,346,000.0 SDG (1,335,636.36 US$) HH/annum. Gum Arabic alone accounted for 38%, followed by sorghum grain and fodder 35%, and cash crops (sesame) 18%. This value would be many time higher if other indirect values (non-marketable) services such as shade, aesthetic and recreation, environmental protection, biodiversity and carbon sequestration are quantified. The goods and services mentioned above provide sustainable income to the farmer directly and viable benefits to the region indirectly. Hence, AFS in the study sites shows the way to reconcile two conflicting goals: short-term food and livelihood needs with long-term environmental conservation and improvement. The study provides evidence that the high local perceived values of AFS in the study sites constitute a central means of livelihood, whereas its contribution to the local economy. The study stresses the need to quantify the monetary values of non-marketed products to consistently account for resource availability and usage to further sound policy decisions. Tenure security, farmer support services and human capital development were major areas identified for policy development.展开更多
The objectives of the present study were: 1) to identify the prioritized marketable natural products (NPs) from agroforestry systems (AFS), and 2) to conduct market value chain analyses of the most important and prior...The objectives of the present study were: 1) to identify the prioritized marketable natural products (NPs) from agroforestry systems (AFS), and 2) to conduct market value chain analyses of the most important and prioritized NPs to identify markets and marketing channels;actors, functions and characteristics;constraints and opportunities to entry and growth;opportunities for value addition, and conduct analysis of strengths, weaknesses, opportunities and threats (SWOT analysis). The study was conducted in the Refugees’ camps and their hosting communities in Eastern Sudan. Using the participatory value chain analysis (PVCA) approach, it was found that communities in the project sites obtained a multiplicity of NPs for sustenance and for increasing their incomes. Eight products were identified and ranked as the most important NPs with greatest opportunities for enterprise development at the community level. These are: gum Arabic, honey, fodder, non-timber forest products (NTFPs) and tree seeds. Gum Arabic has been shown to score higher ranks in terms of a) marketability b) ecological suitability (availability), c) social suitability, and d) potential for value addition. The results show that marketing of gum Arabic in the study site is characterized by a large number of producers and relatively few traders and companies work through seven marketing channels. The results demonstrate that in the customary marketing channel there is an upward skewed benefit distribution among the value chain actors. The total relative commercialization margin was 80% indicating that “traders” accrued higher proportion, while “producers”, receive less income (20%) of the end market price. Poor land security, one-sided prices, taxes and levies, lack of finance and appropriate skills are major impediments to gum commodity growth and development. One of the most important opportunities for growth and entry of Gum Arabic are: it is natural organic product and thus well-fit for fair trade, environmentally sustainable and organic market development. Numerous opportunities exist in the site for value addition and distribution synergies and gender-specific development, including that gum Arabic has high synergy with natural resource management and other sectors for enhancing regional and national growth. The study concludes that Gum Arabic production and marketing is financially profitable for producers, traders and companies and has the potential to open new markets and bring new opportunities to smallholder farmers. However, technical, financial, and institutional support could result in an increase in local actors’ income and contribute to sustainability of the supply of the product.展开更多
As a part of an effort to roll back malaria in Nigeria, exploring the use of geographically related tools triggered the use of modern approaches of knowing the spatial distribution of target populations to attain sign...As a part of an effort to roll back malaria in Nigeria, exploring the use of geographically related tools triggered the use of modern approaches of knowing the spatial distribution of target populations to attain significant malaria elimination intervention. GIS tool was used for geographical reconnaissance (GR), providing demographic data on respondents’ household and spatial information on the distribution of households in the selected location. A cross-sectional study design was used to collect spatial data in the two locations, while a quantitative questionnaire was used to collect the household data. The analysis of field data indicated that 49,500 unique households were enumerated and thus included in the Indoor Residual Spraying to prevent malaria infection, covering 424 towns in the two Local Government Areas (LGAs). 383,301 persons were recorded during the GR exercise in Doma and Nassarawa Eggon LGAs out of which 79,339 were children of agesless than five years, with 13,526 pregnant women. Further data analysis revealed that the average number of persons per household in both LGAs was approximately eight. The spatial information from the GR provides a foundation for an updateable database for any future survey for developmental activities in Nigeria. The use of modern GR approach has proved to be accurate, reliable and more cost effective and less cumbersome than the traditional approach in the collection and geo-positioning of household data. Use of Garmin e-Trex GPS handheld instruments to collect household data in the designated areas removed the constraints of expensive Personal Digital Assistants and reduced errors of wrong location coordinates. Several African countries which did not use GR or applied the use of Geospatial tool appropriately had setbacks. The previous study in other countries showed limitations which was characterized by substantial inherent logistical and technical challenges culminating in missed targets. This setback was addressed in our study.展开更多
Headwater streams play a major role for provision of ecosystem services,e.g.drinking water.We investigated a high-altitude headwater catchment of the Kharaa River(including 411st-order rivers)to understand the impact ...Headwater streams play a major role for provision of ecosystem services,e.g.drinking water.We investigated a high-altitude headwater catchment of the Kharaa River(including 411st-order rivers)to understand the impact of land cover(especially forest cover),environment and human usage on runoff,chemical water quality and macroinvertebrate fauna in a river basin under discontinuous permafrost conditions in an arid,sparsely populated region of Mongolia.To verify our hypotheses that different landuses and environmental impacts in permafrost headwaters influence water quality,we investigated 105 sampling sites,37 of them at intermittent stream sections without water flow.Discharge was positively impacted by land cover types steppe,grassland and forest and negatively by shrubland,forest burnt by wild fires(indicating a reduction of permafrost)and slope.Water quality was affected by altitude,longitude and latitude,shrub growth and water temperature.Shannon diversity of macroinvertebrates was driven by water temperature,iron content of the water,flow velocity,and subbasin size(adjusted R^(2)=0.54).Sample plots clustered in three groups that differed in water chemistry,macroinvertebrate diversity,species composition and bio-indicators.Our study confirms that steppes and grasslands have a higher contribution to runoff than forests,forest cover has a positive impact on water quality,and diversity of macroinvertebrates is higher in sites with less nutrients and pollutants.The excellent ecological status of the upper reaches of the Kharaa is severely threatened by forest fires and human-induced climate change and urgently needs to be conserved.展开更多
Aims Hyptis suaveolens(L.)Poit is an important invader of the tropical and sub-tropical regions of the world.In our study,it has been inves-tigated that how does the H.suaveolens invasion regulate plant spe-cies diver...Aims Hyptis suaveolens(L.)Poit is an important invader of the tropical and sub-tropical regions of the world.In our study,it has been inves-tigated that how does the H.suaveolens invasion regulate plant spe-cies diversity across the seasons in the dry tropical grassland.We hypothesized that a shift in soil inorganic-N availability is caused by invasion,and this shift is integral to access the invasion effect on plant diversity.Methods The study was performed in experimental plots at the Botanical Garden of the Banaras Hindu University(25°16′3.3″N and 82°59′22.7″E),Varanasi,Uttar Pradesh,India.Five replicates(each,2×2m)of non-invaded grassland plots(NIG)and five grassland plots invaded with H.suaveolens(IG)were established.These plots were constructed by transplanting indigenous grassland patches from an adjacent native grassland.In the invaded plots,20 indi-viduals of H.suaveolens were transplanted per plot.After 1 year of establishment,diversity attributes and soil properties were recorded from these plots in three seasons as per standard protocol.Important Findings The results indicated that Hyptis invasion negatively affects plant diversity,with relatively higher impact in rainy season as compared to the winter season.IG exhibited lower soil mois-ture content and temperature than NIG in rainy season,whereas soil ammonium-N,nitrate-N,total inorganic-N,N mineralization registered higher values for IG than NIG in both rainy and win-ter season.Diversity indices were negatively correlated with soil inorganic-N pool and N mineralization.However,these indices were positively correlated with microbial biomass carbon(MBC),and the correlation coefficient for this relationship was higher for rainy season as compared to winter.Species richness(r=0.65)and Shannon diversity(r=0.757)were significantly correlated with the ratio of ammonium-N to nitrate-N.The negative effect of invasion by H.suaveolens on the plant diversity is possibly mediated by the effect of invasion on N mineralization processes(mainly nitrification)and the availability of soil inorganic-N pools.The study indicates that Hyptis invasion has an enormous poten-tial to change the structure and composition of plant communities in the dry tropical grasslands.展开更多
基金supported by the National Key Research&Development Project of China(Grant No.2016YFC0402209)and the China Scholarship Council.
文摘Accurate capture and presentation of the interactive feedback relationships among various objectives in multi-objective reservoir operation is essential for maximizing operational benefits.In this study,the niche theory of ecology was innovatively applied to the field of reservoir operation,and a novel state-relationship(S-R)measurement analysis method was developed for multi-objective reservoir operation.This method enables the study of interaction among multiple objectives.This method was used to investigate the relationship among the objectives of power generation,water supply,and ecological protection for cascade reservoir operation in the Wujiang River Basin in China.The results indicated that the ecological protection objective was the most competitive in acquiring and capturing resources like flow and water level,while the water supply objective was the weakest.Power generation competed most strongly with ecological protection and relatively weakly with water supply.These findings facilitate decision-making throughout the reservoir operation process in the region.The S-R method based on the niche theory is convenient,efficient,and intuitive,allowing for the quantification of feedback relationships among objectives without requiring the solution of the Pareto frontier of a multi-objective problem in advance.This method provides a novel and feasible idea for studying multi-objective interactions.
基金the Tongji University, Shanghai, and the Chongqing University, Chongqing, as part of the MICROTOX project ("Transformation, Bioaccumulation and Toxicity of Organic Micropollutants in the Yangtze Three Gorges Reservoir" No. FKZ 02WT1141)+5 种基金the Sino-German joint environmental research program "Yangtze-Hydro - Sustainable Management of the Newly Created Ecosystem at the Three Gorges Dam" (No. FKZ 02WT Bergmann et al. (2011) www.yangtzeproject.de)part of the research cluster "Pollutants/Water/Sediment-Impacts of Transformation and Transportation Processes on the Yangtze Water Quality"supported by a cooperation project with Chinese colleagues also sponsored by the Federal Ministry of Education and Research, Germany (No. DLR FKZ 01DO12007)the Chinese 111 Program
文摘Besides obvious benefits,the Three Gorges Dam＇s construction resulted in new pollution scenarios with the potentials to threaten the Three Gorges Reservoir（TGR） ecosystem.In order to record organic contamination,to find links to ecotoxicological impacts and to serve as reference for ensuing monitoring,several sites in the TGR area were screened applying the triad approach with additional lines-of-evidence as a holistic assessment method.Sediments and the benthic fish species Pelteobagrus vachellii were sampled in 2011 and 2012 to determine organic pollution levels,mutagenic potentials and genotoxic impacts.Two regional hot-spots near the cities of Chongqing and Kaixian were identified and further investigated in 2013.Only polycyclic aromatic hydrocarbons（PAHs） could be detected in sediments in 2011（165-1653 ng/g）,emphasizing their roles as key pollutants of the area.Their ubiquity was confirmed at Chongqing（150-433 ng/g） and Kaixian（127-590 ng/g） in2013.Concentrations were comparable to other major Chinese and German rivers.However,the immense sediment influx suggested a deposition of 216-636 kg PAH/day（0.2-0.6 mg PAH/（m2·day））,indicating an ecotoxicological risk.PAH source analysis highlighted primary impacts of combustion sources on the more industrialized upper TGR section,whereas petrogenic sources dominated the mid-low section.Furthermore,sediment extracts from several sites exhibited significant activities of frameshift promutagens in the Ames fluctuation assay.Additionally,significant genotoxic impairments in erythrocytes of P.vachellii were detected（Chongqing/Kaixian）,demonstrating the relevance of genotoxicity as animportant mode of action in the TGR＇s fish.PAHs,their derivatives and non-target compounds are considered as main causative agents.
文摘It is globally accepted that soil carbon （C） dynamics are at the core of interlinked environmental problems, deteriorating soil quality and changing climate. Its management remains a complex enigma for the scientific community due to its intricate relationship with soil nitrogen （N） availability and moisture-temperature interactions. This article reviews the management aspects of soil C dynamics in light of recent advances, particularly in relation to the availability of inorganic N pools and associated microbial processes under changing climate. Globally, drastic alterations in soil C dynamics under changing land use and management practices have been primarily attributed to the variation in soil N availability, resulting in a higher decomposition rate and a considerable decline in soil organic C （SOC） levels due to increased soil CO2 emissions, degraded soil quality, and increased atmospheric CO2 concentrations, leading to climate warming. Predicted climate warming is proposed to enhance SOC decomposition, which may further increase soil N availability, leading to higher soil CO2 effiux. However, a literature survey revealed that soil may also act as a potential C sink, if we could manage soil inorganic N pools and link microbial processes properly. Studies also indicated that the relative, rather than the absolute, availability of inorganic N pools might be of key importance under changing climate, as these N pools are variably affected by moisture-temperature interactions, and they have variable impacts on SOC turnover. Therefore, multi-factorial studies are required to understand how the relative availability of inorganic N pools and associated microbial processes may determine SOC dynamics for improved soil C management.
文摘To understand the reason for the success of weeds,we investigated the energetic cost of leaf construction,and certain ecophysiological traits of rice and its dominant weeds.On physiological basis among all weeds,Caesulia axillaris Roxburgh was found to be the most serious,followed by Echinochloa cruss-galli L.Beauv and Echinochloa colonum L.Link,while Fimbristylis miliaceae L.Vahl and Cyperus iria L.were moderate weeds of the rice fields.C.axillaris had the lowest leaf construction cost （LCC） both on a mass basis （1.15 g/g） and on a unit area basis （22.93 g/m2）.Comparatively higher specific leaf area,photosynthetic rate,photosynthetic nitrogen use efficiency,leaf area ratio and leaf area index provided C.axillaris with further competitive advantage.Low LCC suggests that weeds utilize carbon resource more efficiently than the crop and potentially spend the saved energy on other competitive strategies viz.seed production,biomass production and high relative growth rate,which results in low crop yield and increase in weed seed bank.
文摘The objective of this paper is to institute farmers’ own perceptions of the on-and off-farm benefits of agroforestry systems (AFS). Using use value approach, this paper presents empirical evidence on the use values of three types of AFS practiced by the refugees and their hosting communities in Eastern Sudan. The total economic value (TEV) was applied as a framework to estimate the ecosystem values of AFS under study. Goods values were estimated using specific market values, while the services values were qualitatively described according to local perceived values of the local communities. Perceived TEV of AFS includes marketable and non-marketable goods and services. The main direct marketable and sustainable high value products include: food, cash crops, firewood, gum, fodder, NTFPs medicine, fodder, and honey. The valuation results reveal that AFS in the project sites have significantly contributed to the livelihoods of the local communities. Overall, the average net direct-use value of marketable products across all sites was estimated at 7,346,000.0 SDG (1,335,636.36 US$) HH/annum. Gum Arabic alone accounted for 38%, followed by sorghum grain and fodder 35%, and cash crops (sesame) 18%. This value would be many time higher if other indirect values (non-marketable) services such as shade, aesthetic and recreation, environmental protection, biodiversity and carbon sequestration are quantified. The goods and services mentioned above provide sustainable income to the farmer directly and viable benefits to the region indirectly. Hence, AFS in the study sites shows the way to reconcile two conflicting goals: short-term food and livelihood needs with long-term environmental conservation and improvement. The study provides evidence that the high local perceived values of AFS in the study sites constitute a central means of livelihood, whereas its contribution to the local economy. The study stresses the need to quantify the monetary values of non-marketed products to consistently account for resource availability and usage to further sound policy decisions. Tenure security, farmer support services and human capital development were major areas identified for policy development.
文摘The objectives of the present study were: 1) to identify the prioritized marketable natural products (NPs) from agroforestry systems (AFS), and 2) to conduct market value chain analyses of the most important and prioritized NPs to identify markets and marketing channels;actors, functions and characteristics;constraints and opportunities to entry and growth;opportunities for value addition, and conduct analysis of strengths, weaknesses, opportunities and threats (SWOT analysis). The study was conducted in the Refugees’ camps and their hosting communities in Eastern Sudan. Using the participatory value chain analysis (PVCA) approach, it was found that communities in the project sites obtained a multiplicity of NPs for sustenance and for increasing their incomes. Eight products were identified and ranked as the most important NPs with greatest opportunities for enterprise development at the community level. These are: gum Arabic, honey, fodder, non-timber forest products (NTFPs) and tree seeds. Gum Arabic has been shown to score higher ranks in terms of a) marketability b) ecological suitability (availability), c) social suitability, and d) potential for value addition. The results show that marketing of gum Arabic in the study site is characterized by a large number of producers and relatively few traders and companies work through seven marketing channels. The results demonstrate that in the customary marketing channel there is an upward skewed benefit distribution among the value chain actors. The total relative commercialization margin was 80% indicating that “traders” accrued higher proportion, while “producers”, receive less income (20%) of the end market price. Poor land security, one-sided prices, taxes and levies, lack of finance and appropriate skills are major impediments to gum commodity growth and development. One of the most important opportunities for growth and entry of Gum Arabic are: it is natural organic product and thus well-fit for fair trade, environmentally sustainable and organic market development. Numerous opportunities exist in the site for value addition and distribution synergies and gender-specific development, including that gum Arabic has high synergy with natural resource management and other sectors for enhancing regional and national growth. The study concludes that Gum Arabic production and marketing is financially profitable for producers, traders and companies and has the potential to open new markets and bring new opportunities to smallholder farmers. However, technical, financial, and institutional support could result in an increase in local actors’ income and contribute to sustainability of the supply of the product.
文摘As a part of an effort to roll back malaria in Nigeria, exploring the use of geographically related tools triggered the use of modern approaches of knowing the spatial distribution of target populations to attain significant malaria elimination intervention. GIS tool was used for geographical reconnaissance (GR), providing demographic data on respondents’ household and spatial information on the distribution of households in the selected location. A cross-sectional study design was used to collect spatial data in the two locations, while a quantitative questionnaire was used to collect the household data. The analysis of field data indicated that 49,500 unique households were enumerated and thus included in the Indoor Residual Spraying to prevent malaria infection, covering 424 towns in the two Local Government Areas (LGAs). 383,301 persons were recorded during the GR exercise in Doma and Nassarawa Eggon LGAs out of which 79,339 were children of agesless than five years, with 13,526 pregnant women. Further data analysis revealed that the average number of persons per household in both LGAs was approximately eight. The spatial information from the GR provides a foundation for an updateable database for any future survey for developmental activities in Nigeria. The use of modern GR approach has proved to be accurate, reliable and more cost effective and less cumbersome than the traditional approach in the collection and geo-positioning of household data. Use of Garmin e-Trex GPS handheld instruments to collect household data in the designated areas removed the constraints of expensive Personal Digital Assistants and reduced errors of wrong location coordinates. Several African countries which did not use GR or applied the use of Geospatial tool appropriately had setbacks. The previous study in other countries showed limitations which was characterized by substantial inherent logistical and technical challenges culminating in missed targets. This setback was addressed in our study.
基金financially supported by the German Federal Ministry for Economic Cooperation and Development(grant number:BMZ 81212690)and a‘Forschung vor Ort’grant for G.K.of the Max Weber-Program of the State of Bavaria.Special thanks are due to the Deutsche Gesellschaft für Internationale Zusammenarbeit(GIZ)GmbH,especially Klaus Schmidt-Corsitto,at that time Programme Director for“Biodiversity and Adaptation of Key Forest Ecosystems to Climate Change II Program”of GIZ and many employees of GIZ Mongolia.
文摘Headwater streams play a major role for provision of ecosystem services,e.g.drinking water.We investigated a high-altitude headwater catchment of the Kharaa River(including 411st-order rivers)to understand the impact of land cover(especially forest cover),environment and human usage on runoff,chemical water quality and macroinvertebrate fauna in a river basin under discontinuous permafrost conditions in an arid,sparsely populated region of Mongolia.To verify our hypotheses that different landuses and environmental impacts in permafrost headwaters influence water quality,we investigated 105 sampling sites,37 of them at intermittent stream sections without water flow.Discharge was positively impacted by land cover types steppe,grassland and forest and negatively by shrubland,forest burnt by wild fires(indicating a reduction of permafrost)and slope.Water quality was affected by altitude,longitude and latitude,shrub growth and water temperature.Shannon diversity of macroinvertebrates was driven by water temperature,iron content of the water,flow velocity,and subbasin size(adjusted R^(2)=0.54).Sample plots clustered in three groups that differed in water chemistry,macroinvertebrate diversity,species composition and bio-indicators.Our study confirms that steppes and grasslands have a higher contribution to runoff than forests,forest cover has a positive impact on water quality,and diversity of macroinvertebrates is higher in sites with less nutrients and pollutants.The excellent ecological status of the upper reaches of the Kharaa is severely threatened by forest fires and human-induced climate change and urgently needs to be conserved.
文摘Aims Hyptis suaveolens(L.)Poit is an important invader of the tropical and sub-tropical regions of the world.In our study,it has been inves-tigated that how does the H.suaveolens invasion regulate plant spe-cies diversity across the seasons in the dry tropical grassland.We hypothesized that a shift in soil inorganic-N availability is caused by invasion,and this shift is integral to access the invasion effect on plant diversity.Methods The study was performed in experimental plots at the Botanical Garden of the Banaras Hindu University(25°16′3.3″N and 82°59′22.7″E),Varanasi,Uttar Pradesh,India.Five replicates(each,2×2m)of non-invaded grassland plots(NIG)and five grassland plots invaded with H.suaveolens(IG)were established.These plots were constructed by transplanting indigenous grassland patches from an adjacent native grassland.In the invaded plots,20 indi-viduals of H.suaveolens were transplanted per plot.After 1 year of establishment,diversity attributes and soil properties were recorded from these plots in three seasons as per standard protocol.Important Findings The results indicated that Hyptis invasion negatively affects plant diversity,with relatively higher impact in rainy season as compared to the winter season.IG exhibited lower soil mois-ture content and temperature than NIG in rainy season,whereas soil ammonium-N,nitrate-N,total inorganic-N,N mineralization registered higher values for IG than NIG in both rainy and win-ter season.Diversity indices were negatively correlated with soil inorganic-N pool and N mineralization.However,these indices were positively correlated with microbial biomass carbon(MBC),and the correlation coefficient for this relationship was higher for rainy season as compared to winter.Species richness(r=0.65)and Shannon diversity(r=0.757)were significantly correlated with the ratio of ammonium-N to nitrate-N.The negative effect of invasion by H.suaveolens on the plant diversity is possibly mediated by the effect of invasion on N mineralization processes(mainly nitrification)and the availability of soil inorganic-N pools.The study indicates that Hyptis invasion has an enormous poten-tial to change the structure and composition of plant communities in the dry tropical grasslands.
