Influence of Dams on River Ecosystem and Its Countermeasures

Dam construction is an important engineering measure in dealing with the relationship between water and human being. However, with dam construction, some disadvantages to the river basin may be caused, including flow flux of downstream changed, flooded area reduced, river species and other organisms changed and substance sedimentation. Furthermore, it brings some diseases to human being and human residential areas reduced too. Based on the basic principles of ecohydralic engineering, some countermeasures to minimize the negative effects on rivers were put forward. They are reservoir ecological regulation, ecohydraulic engineering construction and comprehensive water pollution treatment.

Impacts of Human Activities on River Ecosystems

This paper analyzes the impact of human activities on river ecosystems from two aspects of agricultural production and watershed water conservancy project construction. Among them, dambased water conservancy projects have caused runoff patterns and artificial segmentation of rivers, which has seriously damaged the energy and material of river corridors as well as the capacity of species to transport the passage. Modern agricultural production not only uses a lot of pesticides and chemical fertilizers, but also occupies a large number of terraces and floodplains, directly leading to the emergence of non-point source pollution. Sometimes the runoff characteristics of the city will also be changed, so the ecological value of the rivers in the city is seriously damaged under such circumstances.

Ecological restoration for river ecosystems: comparing the Huangpu River in Shanghai and the Hudson River in New York

Starting in the 1960s,a great deal of effort and capital was invested in an endeavor to significantlyimprove the quality of surface water around the United States,particularly in metropolises like New YorkCity,New York.The Hudson River has been at the forefront of these efforts and has benefited immenselyfrom this campaign.In parts of the developing world,such as China,similar efforts are beginning to gatherthe same type of momentum.Within the past decade,the Huangpu River,which flows through Shanghaiinto the Yangtze Estuary of China,has been a target for ecological restoration and management.It is possibleto draw parallels between the cleanup efforts involved in improving the environmental conditions of theHuangpu and Hudson Rivers.Using the methodologies of series comparison(SCM),water quality index(WQI)modeling,consideration of ecological engineering,and policy strategy design,we comparativelystudied the topography,functions,environmental conditions,ecological engineering countermeasures,andmanagement policies of the two rivers to assist future forecasting of ecological restoration efforts in China.

Two Village Ecosystems in the Upper Minjiang River, China: A Comparison of Emergy Flow

By using the concept of emergy and method of emergy analysis, this paper has studied two mountain settlement (village) ecosystems in two aspects: input and output of energy in the agro-systems and the use of fuel energy. The result reveals that the settlement agro-system in the valley of Minjiang River is better in both structure and function than that at the so-called half-high mountain. The former one is higher than the latter one regarding such indices as emergy yield ratio, labor productivity of emergy and emergy sustainable index, but lower than the latter one regarding environmental loading ratio. In terms of fuel emergy, the settlement in the valley enjoys more diversified sources and is less depending on bio-energy while the settlement at the half-high mountain has only one source (i. e. fuel wood) , much depending on bio-energy, may exert a greater pressure on environment.

Changes of Coastal Wetland Ecosystems in the Yellow River Delta and Protection Countermeasures to Them

Coastal wetlands in the Yellow River Delta are typical new wetland ecosystems in warm temperate zone. In recent years, influenced by natural and human factors, these coastal wetlands in the Yellow River Delta have undergone changes of landscape fragmentation, vegetation degradation, pollution, species reduction, and harmful exotic species invasion. These changes have influenced sustainable and healthy development of marine economy of the Yellow River Delta. To protect natural ecological environment of the Yellow River Delta, the authors recommended that it should establish and improve policies, laws and regulations of wetland protection; carry out wetland resource investigation and assessment and monitoring; strengthen comprehensive protection and control of wetland; reduce wetland degradation and promote sustainable use of wetland.

Socio-Economic Drivers of Degradation and Their Implication on Conservation of River Lumi Riparian Ecosystem in Kenya

Riparian forests ecosystems play significant role in biodiversity conservation and provision of ecosystem goods and services which support local livelihoods. However, riparian ecosystems are threatened by degradation attributed to anthropogenic activities. Understanding the interaction between anthropogenic activities and socio-economic factors, and their associated impact on riparian degradation is essential for designing appropriate management strategies for these ecosystems. This study assessed the socio-economic factors that drive degradation and their implication on conservation of River Lumi riparian ecosystem. Semi-structured questionnaires, Focus Group Discussion (FGDs) and key informant interviews were used to collect the data. The findings indicate that crop farming and livestock production were the main sources of livelihood practiced by 84% and 70% of the households respectively. Consequently, agricultural intensification resulting from increased demand for agricultural commodities (33%), over-grazing coupled with influx of livestock from private ranches and neighbouring pastoralist Maasai community (20%), and deforestation fuelled by population increase (17%) were the main drivers of degradation in River Lumi riparian ecosystem. The findings indicate that about 91% of the adjacent communities are dependent on River Lumi for their sustenance and their livelihoods will be affected by continued degradation of the riparian ecosystem;thus there is need for development of appropriate management strategies including sustainable livelihood systems to conserve River Lumi riparian ecosystem.

Evaluation of oasis ecosystem risk by reliability theory in an arid area: A case study in the Shiyang River Basin, China

Ecosystem risk is a new concept in understanding environmental problems. It is important to study and develop quantitative methods for regional ecosystem risk analysis. In this study, some new indicators and methods for measuring oasis ecosystem risk were established using reliability theory. These indicators are linked to water resource, which is the key restricting factor in arid area oasis ecosystems. They have clear meanings and can also be compared in different arid area oases. A case study in the Liangzhou oasis of the Shiyang River Basin in China shows how to calculate these ecosystem risk indicators. The results of the case study are as follows： the reliability indicator, risk indicator, stability indicator, and integrated loss indicator of the Liangzhou oasis are 0.686, 0.314, 0.743, and 0.301, respectively. This means that the reliability degree of the oasis＇s ecosystem safety is 68.6%; the degree of risk that it is unsafe is 31.4%; the stability degree is 74.3%; and 30.1% of the oasis＇s area is supported by over-exploiting underground water and damaging the lower reaches of the ecosystem. This result can be used as a guide in controlling and managing ecosystem risk in the research area.

Changes in stress within grassland ecosystems in the three counties of the source regions of the Yangtze and Yellow Rivers

Based on a database of more than 40 years of second production process and energy flow records for Maduo,Qumalai and Yushu counties,a dynamic model of the stress within grassland ecosys-tems was established using a nonlinear regression method for this source regions of the Yangtze and Yel-low Rivers.The results show that dynamic curves of stress within grassland ecosystems in the three coun-ties were in the shape of an inverted 'U' during the period 1965-2007.It also revealed that the variation in actual amount of livestock inventories reflected the general trends of the stress within the grassland eco-systems in the source regions,although there were many other factors for the increase or reduction in grassland ecosystem stress.

Land Use and Land Cover Change along River Lumi Riparian Ecosystem in Kenya: Implications on Local Livelihoods

Riparian forests minimize impacts of land degradation on stream ecosystems and provide direct and indirect benefits to people. However, these ecosystems are threatened by degradation and deforestation attributed to land use changes. River Lumi riparian ecosystem in Taita Taveta County in Kenya has experienced rapid and extensive land use changes over the past three decades in response to economic, institutional and demographic factors. There is growing concern of riparian degradation attributed to land use change with far reaching implications on local livelihoods. A study was conducted to examine the patterns of land use and land cover change along River Lumi riparian ecosystem between 1987 and 2019. The aim of the study was to ascertain the impacts of land use and land cover change on local livelihoods. Landsat images were used to assess land use and land cover change while socio-economic data was collected from 353 households in Njukini, Chala and Mboghoni located in the upper, middle and lower sections of River Lumi ecosystem respectively. Research evidence authenticated that the area under farmlands, settlement and water body increased by 20.5%, 112.1% and 2.3% respectively between 1987 and 2019 while area under forest patches, grazing land and riverine vegetation decreased by 52.7%, 3.0%, and 36.6% respectively. The increase in population in surrounding areas coupled with encroachment of the riparian areas for crop farming and livestock grazing resulted to loss of riparian forest patches/vegetation and associated biodiversity with negative implications on household livelihoods. The implication of these results is the need for land use regulations and management interventions at the County level to arrest further encroachment of River Lumi riparian ecosystem and consequent loss of biodiversity and livelihoods.

Simulating the responses of a low-trophic ecosystem in the East China Sea to decadal changes in nutrient load from the Changjiang(Yangtze) River

Using a three-dimensional coupled biophysical model,we simulated the responses of a lowtrophic ecosystem in the East China Sea(ECS)to long-term changes in nutrient load from the Changjiang(Yangtze)River over the period of 1960–2005.Two major factors aff ected changes in nutrient load:changes in river discharge and the concentration of nutrients in the river water.Increasing or decreasing Changjiang discharge induced different responses in the concentrations of nutrients,phytoplankton,and detritus in the ECS.Changes in dissolved inorganic nitrogen(DIN),silicate(SIL),phytoplankton,and detritus could be identified over a large area of the ECS shelf,but changes in dissolved inorganic phosphate(DIP)were limited to a small area close to the river mouth.The high DIN:DIP and SIL:DIP ratios in the river water were likely associated with the diff erent responses in DIN,DIP,and SIL.As DIP is a candidate limiting nutrient,perturbations in DIP resulting from changes in the Changjiang discharge are quickly consumed through primary production.It is interesting that an increase in the Changjiang discharge did not always lead to an increase in phytoplankton levels in the ECS.Phytoplankton decreases could be found in some areas close to the river mouth.A likely cause of the reduction in phytoplankton was a change in the hydrodynamic field associated with the river plume,although the present model is not suitable for examining the possibility in detail.Increases in DIN and DIP concentrations in the river water primarily led to increases in DIN,DIP,phytoplankton,and detritus levels in the ECS,whereas decreases in the SIL concentration in river water led to lower SIL concentrations in the ECS,indicating that SIL is not a limiting nutrient for photosynthesis,based on our model results from 1960 to 2005.In both of the above-mentioned cases,the sediment accumulation rate of detritus exhibited a large spatial variation near the river mouth,suggesting that core sample data should be carefully interpreted.

Aboveground biomass of the alpine shrub ecosystems in Three-River Source Region of the Tibetan Plateau

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.

Current Situation and Ideas of Protection and Restoration of Aquatic Ecosystems in Rivers and Lakes of China

Based on the investigation and analysis of protection and restoration of aquatic ecosystems in rivers and lakes of China, the ideas and measures of restoring aquatic ecosystems were proposed to build healthy aquatic ecosystems of rivers and lakes in China, such as setting scientific and clear goals, improving the standard adopted by wastewater treatment plants, controlling sources of pollutants and intercepting pollutants, collec- tion of blue-green algae, water transfer, dredging, reducing the quantity of blue-green algae, restoring reed wetlands on a large scale, combing dredging and base raise of restored reed wetlands, making full use of microorganisms, and implementing effective management, technology integra- tion and innovation.

Ecosystems Services of the Tropical Rain Forest Environment: Lessons from the Cross River National Park, Nigeria

This paper essayed to examine ecosystem functions with a case study of the tropical rainforest environment of the Cross River National Park, Nigeria. The paper highlighted the important functions of the ecosystems to include Purification of air and water mitigation of floods and droughts, detoxification and decomposition of wastes, generation and renewal of soil and natural vegetation, pollination of crops and natural vegetation, control of the vast majority of potential agricultural pests, dispersal of seeds and translocation of nutrients, maintenance of biodiversity, protection from the sun’s harmful ultraviolet rays among others. Problems associated with the rainforest ecosystems among which are logging, traditional methods of farming, poaching, excessive noise and encroachment were identified. The paper concluded by highlighting the way forward among others that, awareness creation should be stepped-up in Support Zone Communities;indigenes should be educated periodically on the benefits of the ecosystem services to not just humans but the forest resources and biodiversity themselves.

AREAL DIFFERENTIATION AND CONSTRUCTION OF OASIS AGRICULTURAL ECOSYSTEM IN THE SHIYANG RIVER BASIN

On the basis of the study on areal differentiation of the natural environment of oasis agriculture ecosystems in the Shiyang River Basin, this paper comparatively analyzes the natural productivities, water economic benefits, production efficiency, ecological stabilities and developmental conditions of the Wuwei Oasis agricultural ecosystem in the middle reaches of the river basin and the Minqin Oasis agricultural ecosystem in the lower reaches. Under a same management level and investment of . material and energy, primary productiveness and economic benefits of the former are higher than those of the latter. Construction directions of Wuwei and Minqin oases should be different in order to alleviate the water- use contradiction between the middle and lower reaches. The construction objective of Wuwei Oasis should be efficient irrigated farming production system and Minqin Oasis should become a mixed forestry-pastoral-farming ecosystem taking ecological protection as its major function.

保护野性河流已刻不容缓——中国野性河流分布现状与保护建议

野性河流指未经人工拦蓄,隐藏于自然之中难以到达,其水域岸线及整个流域均保持原始自然状态,水体未受污染的河流或河段。由于其“原始”和未受干扰的特性,野性河流具有重要的生态环境、景观和科学研究价值。近几十年,由于经济社会发展需要,我国绝大部分河流受到筑坝、取水、排污等人类活动的影响,野性河流数量和长度锐减,其提供水生态环境基准、原生态景观、水生生物良好栖息地等功能大幅度削弱,开展和加强野性河流的保护已刻不容缓,亟须予以高度重视并制定专门措施开展保护工作。

Digitalizing river aquatic ecosystems

Traditional river health assessment relies on limited water quality indices and representative organism activity,but does not comprehensively obtain biotic and abiotic information of the ecosystem.Here,we propose a new approach to evaluate the ecological and health risks of river aquatic ecosystems.First,detailed physicochemical and biological characterization of a river ecosystem can be obtained through pollutant determination(especially emerging pollutants)and DNA/RNA sequencing.Second,supervised machine learning can be applied to perform classification analysis of characterization data and ascertain river ecosystem ecology and health.Our proposed methodology transforms river ecosystem health assessment and can be applied in river management.

城市蔓延对生态系统服务流的影响研究进展及对长江流域的启示

全面梳理城市蔓延对生态系统服务流的影响研究现状,有利于促进区域社会经济可持续发展。综述了城市蔓延对生态系统服务流的影响研究,结果表明:城市蔓延对生态系统服务流的影响研究仍处于起步阶段。城市蔓延通过载体传递和流动路径两方面改变了生态系统服务流的流量、流速和流向,导致生态系统服务流总量的减少和空间异质性的增加;城市蔓延的单项指标变化、城市蔓延的尺度以及城市蔓延的多情景模拟是探索城市蔓延对生态系统服务流影响过程的主要切入点;城市蔓延过程中引起的生态系统服务流扩散效应主要源于土地利用类型的变化和人类居住模式的改变。已有研究在一定程度上解释了城市蔓延对生态系统服务流的影响,但在揭示影响机理、剖析影响过程、评估影响效应以及探索生态系统服务流合理分配以促进城市可持续发展等方面的研究还存在较大空白。在此前提下,未来应基于“机理揭示-影响模拟-效应评估”的研究思路,建立长江流域城市蔓延对生态系统服务流影响研究框架,探索长江流域城市可持续发展与生态系统服务流的合理分配方案,实现长江流域生态保护与社会发展的协同共进。