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1.
Water quality of rivers in the drainage basin of Lake Peipsi   总被引:3,自引:3,他引:0  
Enn Loigu  Ülle Leisk 《Hydrobiologia》1996,338(1-3):25-35
Water quality and general regularities that have taken place in the water quality of rivers in the drainage basin of Lake Peipsi have been studied. The lake is located in the basin of the Narva River. Several changes of the water quality of the lake in 1970–1990, caused by increasing human impact, have been observed. The water quality of Lake Peipsi depends on its pollution load whereby the main part of the pollution reaches the lake via rivers. In 1985–1989 an extensive research programme of the lake and its drainage basin was carried out. In this paper a part of these results as well as recent changes in the water quality of the rivers of the Estonian side are studied. In the last years an improvement of the general state of rivers in the drainage basin of Lake Peipsi has taken place; the content of organic substances and nutrients in the inflows of Lake Peipsi and in the Narva River (lake outflow) is decreasing.  相似文献   

2.
We investigated the vegetation structure and density of game birds along a successional gradient created by varying intensity of human settlement in a pastoral community in Shompole group ranch in southern Kenya. We examined four habitat types including heavily-grazed grass in currently occupied settlements, short grass in seasonal settlements, patches of bushed woodland in settlement sites that had been abandoned up to 30 years ago, and tall grass in a wildlife sanctuary. Vegetation biomass was the highest in the sanctuary where livestock are excluded and the lowest in the vicinity of currently occupied settlements. Abundance of doves ( Oena spp . and Streptopelia spp. ) was best associated with moderate grazing and per cent green grass, which provide good foraging opportunities. Francolin and spurfowl ( Francolinus spp .) were positively associated with vegetation biomass. Quail ( Coturnix spp .) were positively associated with tree cover. These data reflect the importance of maintaining a balance of wildlife and livestock grazing with patches of ungrazed grasslands and bushed woodlands in providing a mosaic of habitats that support a diverse population of game birds. The results have wide application for an integrated management approach to livestock, wildlife and game bird management in the savannas.  相似文献   

3.
Historically management of human use of ecosystems has been based around engineering and chemical approaches and through the construction of treatment facilities, effluent controls and setting chemical concentrations, both at end of pipe and in the aquatic environment. However, the general continued degradation of many ecosystems shows these approaches alone are insufficient. In the Laurentian Great Lakes the Great Lakes Water Quality Agreement was first signed in 1972 and ratified in 1978 and in 1987 tacitly acknowledged the problems with a chemical only approach by requiring the development of ecosystem objectives in the 1978 agreement. Furthermore, the agreement specifically identified numerical ecosystem objectives in the 1987 agreement. The evolution of ecosystem objectives in the Great Lakes has expanded from the strictly numerical objectives such as production of lake trout and abundance of the amphipod Pontoporeia hoyi. More recent developments in ecosystem objectives have been the inclusion of indicators for wildlife, habitat, human health and stewardship.Prepared as a discussion paper presented to the United Nations Economic Commission for Europe's seminar on an Ecosystems Approach to Water Management (May 27–31, 1991).  相似文献   

4.
Land use change and human population growth are accelerating the fragmentation and insularization of wildlife habitats worldwide. The conservation and management of wildlife in the resultant ‘island’ ecosystems in the context of global warming is challenging due to the isolation and reduced size of the ecosystems and hence the scale over which ecosystem processes can operate. We analyzed trends in numbers of nine large herbivores in Kenya’s Lake Nakuru National Park to understand how rainfall and temperature variability, surrounding land use changes, and boundary fencing affected wildlife population dynamics inside the park during 1970–2011. Buffalo, zebra and Thomson’s gazelle numbers increased persistently. Grant’s gazelle and impala increased initially then gradually declined. Waterbuck and warthog numbers progressively declined to levels that potentially threatened their local population persistence. The total biomass of ungulates tripled from 1970 to 2011, with buffalo replacing waterbuck as the predominant species in biomass. Increased competition from buffalo and zebra, heightened predation and illicit human harvests probably all contributed to the declines by waterbuck and warthog. Density-dependent limitation of population growth within the park confines was evident for buffalo, impala, eland, giraffe, Grant’s and Thomson’s gazelles. Fluctuations in the lake level related to varying rainfall affected changes in animal abundance through expansion of the lake area and flooding of grasslands bordering the lake. Unusually, the most stressful conditions were associated with high water levels following high rainfall. There was also evidence of carry-over effects from prior habitat conditions affecting all species. The relatively stable populations of all species except warthog and waterbuck demonstrate the remarkable capacity of this small, insularized park to retain viable populations of most of the large herbivores, without much management intervention.  相似文献   

5.
As anthropogenic activity makes deeper incursions into forests, fragmenting habitat, wildlife is forced into closer proximity to humans leading to increased incidences of human–wildlife conflict and wildlife displacement. These same incursions facilitate poaching for the commercial trade in dead and live animals. As a direct result, the number of sanctuaries and internally displaced animals (IDAs) in need of sanctuary placement and rehabilitation are increasing. We focus on internally displaced primates given the prevalence of primate‐focused facilities and anthropomorphic considerations surrounding this taxonomic group. Surveys were distributed globally to map the extent and range of native primate sanctuaries and species. Over 70 facilities care for more than 6,000 native primates comprising 64 species, with almost half listed as endangered or critically endangered. As not all sanctuaries were identified at the time of the survey distribution, we estimate that the actual number of facilities is closer to double this number with a captive population in excess of 10,000 individual primates. Native primate sanctuaries hold significant numbers of primates in long‐term captive care, with less than half (37%) identified as candidates for release. The surveyed sanctuary population accounts for 35% of the world's captive primates, as compared to ISIS‐registered (where ISIS is International Species Information System) zoological facilities, although we estimate that the actual population is closer to 58%. For some species, the sanctuary population represents the only population in captivity. We discuss the prevalence of range‐state sanctuaries and their primate populations, and issues surrounding their future development and management. Am. J. Primatol. 75:116‐134, 2013. © 2012 Wiley Periodicals, Inc.  相似文献   

6.
高原湖泊流域是高原地区人类活动的重要载体,兼具高生态价值和高脆弱性的特点。随着高原湖泊流域城市化和工业化发展加速,湖泊面积萎缩,污染加剧,流域生态环境受损严重,引发了一系列生态环境问题,如水土流失、水污染、湿地退化、生境质量下降等。亟需开展生态修复以平衡经济发展与生态环境保护之间关系,而基于整体保护与系统治理思维诊断并修复生态修复优先区,是科学有序推进国土空间生态保护与修复的重要抓手。基于此,研究以高原湖泊流域典型代表滇池流域为例,利用人类足迹和景观生态风险模型定量评估生态系统所受负向干扰,以最小累积阻力模型和电路理论构建流域生态网络;提取生态网络受负向干扰较高的关键区域为生态修复优先区并提出针对性修复措施。研究表明:(1)滇池流域人类干扰和生态风险整体较高,人类干扰整体呈核心—边缘递减的圈层式分布,中高生态风险占据了绝大部分区域。人类交通网络大幅扩展了人类干扰和生态风险的强度和深度;(2)区域生态网络呈典型湖泊生态网络特点,38条生态廊道呈放射状或环状分布,连通湖区、山区两大生态空间内共23块生态源地,保障区域生态安全;(3)研究共提取生态源地修复优先区73.83km2  相似文献   

7.
Tiger, being a solitary and territorial animal, often tends to move out of protected areas into the surrounding forests. This is especially true in the case of sub-adult animals leading to escalating conflicts and deaths in the surrounding human-dominated landscapes. Unless adequately protected against various human activities, such corridors and surrounding forests will soon disappear, trapping the animals within protected areas with resultant local extinctions. In this paper we ascertain tiger presence, occupancy and numbers in one such partially protected area, the Sathyamangalam forest, located close to better known tiger reserves in India, through non-invasive faecal DNA analysis. Here we highlight the potential of Sathyamangalam as a tiger habitat. Tiger positive faecal samples were considered as evidence to establish occupancy in two different parts of Sathyamangalam, reserve forest and wildlife sanctuary. We collected 103 faecal samples out of which 69 were tiger positive. Species occupancy (psi), was 0.672 (±0.197) with a detection probability of 0.2 (±0.06) in the wildlife sanctuary area; while psi was 0.72 (±0.2) with detection probability of 0.212 (±0.6) in the reserve forest. Further, number of males and females, as determined in our study, was close to the ideal sex ratio in a healthy forest with good prey abundance. This study also highlights the presence of more females in the reserve forest (n = 10) than the wildlife sanctuary (n = 3) possibly indicating lesser disturbance and more prey availability. We recommend that the reserve forest to the north of Sathyamangalam wildlife sanctuary be declared as a tiger reserve. The wildlife sanctuary could serve as a buffer zone between this reserve and Sathyamangalam town which lies to the south of the forest. Proper protection of Sathyamangalam will go a long way in saving the entire landscape and tigers of the Western Ghats of India.  相似文献   

8.
Remote sensing provides multi-dimensional and multi-temporal information about habitat, insights into the significant drivers of change, and the key factors affecting landscape dynamics. Such information is crucial to provide perspective and a more profound understanding of ecological surveys. This study utilizes Google Earth Engine's capability to assess a riverine wetland grassland floodplain in Hastinapur Wildlife Sanctuary (HWS) along the Ganga River, which is a critical habitat for wintering migratory birds, the critically endangered gharial, turtles, aquatic mammals such as otters and dolphins, and cervid species such as swamp deer. We have developed a framework for regular monitoring through rapid habitat assessment, which visualizes the spatio-temporal change in land cover, the seasonal dynamics in water and vegetation, changes due to anthropogenic influences on the landscape, and finally, how these factors affect the habitat availability of species of concern in the HWS. The results show a dynamic river system with high seasonal variations. The vegetation trend shows increasing greenness, indicative of the conversion of grassland, scrubland, and herbaceous cover to more permanent vegetation, which will adversely affect the riparian habitat structure. A habitat suitability index generated through geospatial analysis using the weighted overlay method suggests that 40.07% of the HWS, nearly 767.12 km2, comprising mainly the riverscape, wetland, and riparian grasslands, is suitable habitat for aquatic and semi-aquatic species. However, only 9.93% of the sanctuary comprising 197.27 km2, is available as a core habitat. Further, the area is threatened by encroachment evident from the rapidly increasing land-use intensity and night light pollution, which puts the grasslands sheltered to swamp deer and other wildlife at higher risk leaving almost 27.9% of the area comprising 533.63 km2 unsuitable for wildlife. Urban and agricultural land use has taken over 67% of the sanctuary. An increase in minimum radiance value representing ALAN, from 0.41 to 0.73 W/m2-sr in just six years from 2015 to 2021, shows a reduction in nocturnal darkness, reducing safe niches for wildlife. The study results provide critical baseline information for ecological surveys and a rapid assessment platform for future sanctuary management. Constant monitoring of anthropogenic activities such as farming, settlements, and transport routes threatening the habitat is essential for informed conservation management decisions.  相似文献   

9.
Species diversity of the genus Kephyrion Pascher in the basin of the Sabun River (subzone of northern taiga in western Siberia) is discussed. Its territory holds the Sibirskie Uvaly Nature Park. The genus Kephyrion is represented by 16 specimens in the basin of the Sabun River and by 14 specimens in the bodies of water of the park. Their temperature, visibility, and active reaction of water stimulating vegetation have been identified. Five species and one variety of the genus have been for the first time registered in the flora of western Siberia.  相似文献   

10.
Population and conservation genetics of two freshwater fish species, Notropis heterodon and Notropis heterolepis, were evaluated in north‐eastern Illinois, U.S.A., where both species have severely declined. Fishes were sampled from two remnant populations occurring in small glacial lakes (source samples) and from two man‐made ponds that had been stocked with fishes from those same lakes (sanctuary samples). The goal was to obtain information that would help inform conservation programme planning to reintroduce sanctuary fishes to areas where both species are extirpated. Microsatellite data showed that the two species were genetically quite distinct and there was no evidence of hybridization in either source or sanctuary samples. Within each species, source and sanctuary samples had moderate levels of heterozygosity and were not significantly different from each other. Many alleles observed in the source samples, however, were not detected in the sanctuary samples, indicating that translocation had resulted in reduced allelic diversity of the sanctuary samples. Sibship analysis indicated that full and half sibs occurred within source‐lake samples, thus reducing the effective population size of the reintroduced stock. Taken together, these results suggest that source‐lake stocks rather than sanctuary stocks are more appropriate for future reintroductions of both species in their native range, unless sanctuary populations can be established with hundreds of fishes. Also, fishes should be harvested from multiple locations in source lakes to avoid over‐representation of family groups.  相似文献   

11.
三江源国家公园是我国首批建立的面积最大的国家公园,也是青藏高原第一个国家公园,对青藏高原乃至我国加快构建以国家公园为主体的自然保护地体系具有里程碑式意义。三江源国家公园野生动物多样性水平高且濒危物种占比大,其中兽类和鸟类受威胁比例分别为32.26%和19.90%;具有丰富的国家重点保护物种及青藏高原特有珍稀物种,包括46.77%的中国或青藏高原特有兽类和7.65%的中国特有鸟类,其生物多样性具有全国乃至全球意义的保护价值。本文简要回顾全球野生动物保护研究重要进展和取得的成果,分析三江源野生动物濒危成因,提出了加强三江源国家公园野生动物动态监测、创新栖息地保护技术、建立野生动物迁移廊道及避难所、开展草畜平衡管理、疫源疫病控制、人兽冲突研究和建立野生动物基因资源库等多项野生动物保护和管理对策,为实现三江源国家公园生态环境严格保护、人与自然和谐共生、区域可持续发展战略提供了有益的参考。  相似文献   

12.
Mediterranean ecosystems are rich in wildlife species and habitats. In the last decades human pressure is increasing in lowland and coastal areas, while mountainous and island areas are being abandoned. These changes have substantial impacts on biodiversity protected by EU Directives. Recently agri-environmental schemes and wildlife habitat improvement measures have been taken to prevent biodiversity loss, although only a small proportion of their total budget is targeted directly at biodiversity conservation. Measures for wildlife are generally limited to restricted areas for a short-term period and in most cases have not been evaluated or properly applied. This review examines the influence of farming systems, agri-environmental and wildlife management measures on birds and mammals in Mediterranean agroecosystems. The conclusions are that in Mediterranean agroecosystems the most cost efficient and beneficial conservation measures for bird and mammal species are rotation, intercropping, and the selection of appropriate crops and farming practices. The increased biodiversity in the Mediterranean basin requires special management practices at local levels.  相似文献   

13.
Understanding future ecosystem changes is central to sustainable natural resource management especially when coupled with in-depth understanding of impacts of drivers, such as governance, demographic, economic and climate variations and land use policy. This offers comprehensive information for sustainable ecosystem services provision. A foresight process of systematic and presumptive assessment of future state and ecosystem integrity of Lake Victoria basin, as participatory scenario building technique, is presented. Four scenarios have been illustrated as possible future states of the basin over the next twenty years. Using a scenario building model developed in Ventana Simulation (VENSIM®) platform, the paper presents a scenario methodology for tracking changes in lake basin ecosystem status. Plausible trends in land use change, changes in lake levels and contribution of fisheries are presented. This is part of an initial attempt to setup long-term environmental policy planning strategies for Lake Victoria basin. The assumptions, driving forces, impacts and opportunities under each scenario depict major departure and convergence points for an integrated transboundary diagnosis and analysis of regional issues in the basin as well as strategic action planning for long-term interventions. The findings have been presented in terms of temporal, spatial, biophysical and human well-being dimensions. The attempts in this study can be embedded in a policy framework for basin management priority setting and may guide partnerships for environmental management.  相似文献   

14.
The Tiger (Panthera tigris) population in India has undergone a sharp decline during the last few years. Of the number of factors attributed to this decline, habitat fragmentation has been the most worrisome. Wildlife corridors have long been a subject of discussion amongst wildlife biologists and conservationists with contrasting schools of thought arguing their merits and demerits. However, it is largely believed that wildlife corridors can help minimize genetic isolation, offset fragmentation problems, improve animal dispersal, restore ecological processes and reduce man animal conflict. This study attempted to evaluate the possibilities of identifying a suitable wildlife corridor between two very important wildlife areas of central India--the Kanha National Park and the Pench National Park--with tiger as the focal species. Geographic Information System (GIS) centric Least Cost Path modeling was used to identify likely routes for movement of tigers. Habitat suitability, perennial water bodies, road density, railway tracks, human settlement density and total forest edge were considered as key variables influencing tiger movement across the Kanha-Pench landscape. Each of these variables was weighted in terms of relative importance through an expert consultation process. Using different importance scenarios, three alternate corridor routes were generated of which one was identified as the most promising for tiger dispersal. Weak links--where cover and habitat conditions are currently sub-optimal--were flagged on the corridor route. Interventions aimed at augmenting the identified corridor route have been suggested using accepted wildlife corridor design principles. The involvement of local communities through initiatives such as ecotourism has been stressed as a crucial long term strategy for conservation of the Kanha-Pench wildlife corridor. The results of the study indicate that restoration of the identified wildlife corridors between the two protected areas is technically feasible.  相似文献   

15.
Mitigating crop and livestock loss to wildlife and improving compensation distribution are important for conservation efforts in landscapes where people and wildlife co-occur outside protected areas. The lack of rigorously collected spatial data poses a challenge to management efforts to minimize loss and mitigate conflicts. We surveyed 735 households from 347 villages in a 5154 km2 area surrounding Kanha Tiger Reserve in India. We modeled self-reported household crop and livestock loss as a function of agricultural, demographic and environmental factors, and mitigation measures. We also modeled self-reported compensation received by households as a function of demographic factors, conflict type, reporting to authorities, and wildlife species involved. Seventy-three percent of households reported crop loss and 33% livestock loss in the previous year, but less than 8% reported human injury or death. Crop loss was associated with greater number of cropping months per year and proximity to the park. Livestock loss was associated with grazing animals inside the park and proximity to the park. Among mitigation measures only use of protective physical structures were associated with reduced livestock loss. Compensation distribution was more likely for tiger related incidents, and households reporting loss and located in the buffer. Average estimated probability of crop loss was 0.93 and livestock loss was 0.60 for surveyed households. Estimated crop and livestock loss and compensation distribution were higher for households located inside the buffer. Our approach modeled conflict data to aid managers in identifying potential conflict hotspots, influential factors, and spatially maps risk probability of crop and livestock loss. This approach could help focus allocation of conservation efforts and funds directed at conflict prevention and mitigation where high densities of people and wildlife co-occur.  相似文献   

16.
17.
赵玲玲  夏军  杨芳  杨龙  徐飞 《生态学报》2021,41(12):5054-5065
水是生态系统物质循环和能量流动的重要纽带,水生态系统修复在区域生态系统修复中起到关键作用。粤港澳大湾区剧烈人类活动对江河湖库生态系统造成破坏和干扰,江河湖库污染严重,水生物减少,导致流域水生态服务功能退化甚至丧失;从生态修复科学内涵出发,判断湾区水生态系统健康状况已处于非生物控制跃迁阈值之下;针对该形势,从工程建设、水环境治理、空间规划和管理机制四个方面,梳理湾区近期开展的与水生态修复相关的水生态文明建设、水污染防治行动计划、水生态空间划定和推进河长制等工作,并对其中用到的技术、指标和制度进行条理;然后以茅洲河流域综合治理和广东万里碧道作为水生态修复的点、面代表,从水生态修复的整体目标、采用的技术措施、效果评价的指标体系和管理制度方法等方面分析当前的工作现状;总结湾区现状水生态修复工作,认为湾区水生态系统的非生物修复阶段基本结束;基于生态系统修复理论结合湾区江河湖库生态系统特点,提出适合湾区的水生态修复框架,讨论水生态系统修复面临的问题和未来工作的展望,为大湾区水生态修复提供直接依据。  相似文献   

18.
中国自然保护地体系分类研究   总被引:11,自引:3,他引:8  
欧阳志云  杜傲  徐卫华 《生态学报》2020,40(20):7207-7215
建设自然保护地体系是为子孙后代保留生物多样性资源与自然遗产最有效的途径。自1956年我国建立第一个自然保护区以来,已建设形成覆盖森林、草地、湿地、海洋、荒漠各类生态系统,珍稀濒危动植物物种和种质资源,自然遗迹和自然景观,以及水源保护等各类自然保护地。但由于缺乏自然保护地体系的顶层设计,各类保护地面临功能区分不清晰、空间重叠、管理成效不高等问题。建设以国家公园为主体的自然保护地体系的部署,为理顺我国保护地体系,明确各类保护地的功能定位提供了难得的机会。在分析我国现有自然保护地类型,并参考国际自然保护地体系分类经验的基础上,探讨了我国保护地体系分类,建议将我国自然保护地分为5大类,第I类为自然保护区,第Ⅱ类为国家公园,第Ⅲ类为自然公园,第Ⅳ类为物种与种质资源保护区,第Ⅴ类为生态功能保护区,并分析了各类自然保护地的功能定位和管理目标,以期为自然保护地体系规划建设提供参考。完善我国自然保护地体系分类,根据各类保护地的特点,创新保护地建设政策与机制,加大政府对自然保护地建设力度的同时,发挥全社会力量建设自然保护地,我国自然保护地建设将大有可为。  相似文献   

19.
Impact of extraction of non-timber forest products (NTFPs) was analyzed in a thorn scrub forest in Biligiri Rangaswamy Temple (BRT) wildlife sanctuary, India. Six species are most commonly extracted from BRT scrub for subsistence and income generation by an aboriginal tribe, the Soliga. Although the forest has been provided protection from indiscriminate felling since 1978 under a wildlife sanctuary cover, changes in vegetation structure are still occurring as a consequence of anthropogenic pressure in the form of extraction of fuelwood and other NTFPs. The results indicate that large woody species are being replaced by small woody species. The population structure also is becoming increasingly skewed to the smaller size classes due to extraction-bound mortality of the individuals, particularly those>7 cm dbh and above. The data suggest that the scrub community itself may be a manifestation of long persisting anthropogenic pressure in the form of extraction of a variety of forest products, and it currently represents a downward transition from a deciduous forest to a shrub thicket.  相似文献   

20.
The lake sediment record was used to reconstruct past vegetation dynamics and human impacts from the middle Neolithic (6500 cal. b.p.) to the Middle Ages (1500 cal. b.p.) around Lac d’Antre in the southern Jura mountains of France. This lake was surrounded by the Gallo-Roman sanctuary of Villards d’Héria, which has been widely investigated by archaeologists and enables a comparison between palaeoenvironmental proxies and archaeological data. Pollen and microscopic charcoal analyses were conducted on a 500 cm sediment core with eleven radiocarbon dates providing the chronological control. In a mixed oak woodland context, the successive development of Taxus, Fagus and Abies were mainly caused by climatic variations during the Neolithic, in which there was weak human impact. The first significant signs of human activity were detected during the Bronze Age from 3900 cal. b.p., followed by an increase of human pressure and woodland clearances during the Iron Age, from 2700 cal. b.p. The occupation of the Gallo-Roman sanctuary was continuous with the Iron Age occupation. All the analysed palaeoenvironmental data indicate that the strongest human impact occurred during the Gallo-Roman period, which matches the occupation of Villards d’Héria previously dated by archaeologists from 2000 to 1700 cal. b.p., 1st to 3rd century a.d. Moreover, there appears to have been a new period of human settlement close to the lake at the beginning of the Middle Ages. The low charcoal accumulation rate (CHAR) recorded during the Bronze and Iron Ages suggests that fire was not the main agent used to clear the dense woods to create new cultivated fields and pastures. High CHAR values recorded during the Roman period may represent fire use for domestic and agro-pastoral activities.  相似文献   

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