Study on the oasis corridor landcape in the arid regions based on RS and GIS methods—application of Jinta Oasis,China

The study on the oasis corridor landscape is a new hotspot in the ecological environment research in the arid regions.In oasis,main corridor landscape types include river,ditch ,shelterbelt and road.This paper introduces the basic ecological effects of the corridor landscape on the transporting mass and energy and obstructing desert landscape expansion and incursion.Using Geographic Information System(GIS),we have researched the corridor distribution and its spatial relationship with other landscape types in the Jinta Oasis.Based on the dynamically monitoring on the landscape pattern change of the Jinta Oasis during the latter 10 years by using Remote Sensing(RS) and GIS,the driving functions of the corridors on this change have been analyzed in detail.The analysis results showed that all kinds of corridors‘ characteristics can be quantified by the indexes such as length and width ,ratio of perimeter and area,density and non-heterogeneity.The total corridor length of Jinta Oasis is 1838.5km and its density is 2.1km/km^2.The corridor density of the irrigation land.forest and resident area is maximal,which shows that affection degree of the oasis corridors on them is the most.The improvment of the corridors quality is one of the important driving factors on the irrigation land and so on.The organic combination of the RS and GIS technologies and landscape research methods would be an effective means for the corridor landscape research on arid region oasis.     

Vegetation patterns and nature reserve construction in an extremely-arid desert in Anxi,NW China's Gansu Province

Anxi County is located in the northwestern part of the Hexi Corridor in gansu Province and has the sole national level nature reserve of extremely-arid desert in China.Phytosociological methods (Braun-Blanquet,1964) are used to classify plant community types in this area.Eleven are disting uished,including six of deserts,four of oases and one transitional type between deserts and oases.Direct gradient analysis (DCA) is employed to correlate the distribution of plant communities to physiogeographic conditions.This study makes clear that water is the most important ecological factor for the distribution of plant species and communities in this area.The effects of water have been demonstrated in different ways.A vegetation gradient from lower altitude to higher altitude in the southern part of the reserve is driven by a precipitation gradient.The effects of the depth of ground water table contribute to the differentiation of vegetation from desert to oasis in the flat area.In a finer scale,the washed gullies have obviously higher species richness and also higher vegetation cover than the surround gobi surfaces,possibly caused by the effects of floods.The vegetation patterns demonstrate that the area of Anxi County is a complete landscape unit.The range of the current nature reserve is not large enough for the purpose of conserving the unique biodiversity in this area.     

Insights into effects of algae on decay and distribution of bacterial pathogens in recreational water: Implications for microbial risk management

The decay and distribution of bacterial pathogens in water is an important information for the health risk assessment to guide water safety management, and suspended algae might affect bacterial pathogens in water. This study established microcosms to investigate the effects of algae-related factors on the representative indicators and opportunistic pathogen species in water. We found that suspended algae increased the persistence of targeted species by 1-2 orders of magnitude of concentrations ...     

Upstream-downstream cooperation approach in Guanting Reservoir watershed

A case study is introduced and discussed concerning water dispute of misuse and pollution between up- and down-stream parts. The relations between water usage and local industrial structures are analyzed. Results show it is important to change industrial structures of the target region along with controlling water pollution by technical and engineering methods. Three manners of upstream-downstream cooperation are presented and discussed based on the actual conditions of Guangting Reservoir watershed. Two typical scenarios are supposed and studied along with the local plan on water resources development. The best solution for this cooperation presents a good way to help the upstream developing in a new pattern of eco-economy.     

Landscape dynamitic change in Mu Us Desert derived from Landsat TM data

Landscpae ecology emphasizes large areas and ecological effects of the spatial patterning of ecosystem.Recent developments in landscape ecology emphasized the important relationship between spatial patterns and many ecological processes.Quantitative methods in landscape ecology link spatial patterns and ecological processes at broad spatial and temporal scales.In turn the increased attention on temoral change of ecosystem has highlighted the need for quantitative methods that can analyze patterns.This research applies quantitative methods-change detection to assess the ecosystem temporal change in the arid and semiarid area.Remote sensing offers the temporal change of ecosystem on landscape characteristics.     

Ecological service assessment of human-dominated freshwater ecosystem with a case study in Yangzhou Prefecture, China

Freshwater ecosystems provide a host of services to humanity. These services are now rapidly being lost, not least because of the inability of making the impacts measurable. To overcome this obstacle, assessment frameworks for freshwater ecosystem services are needed. A simple water equivalent framework to assess the ecological services provided by freshwater ecosystems was developed in this study. It translated the occupation of freshwater ecosystem services into biologically freshwater volumes and then compares this consumption to the freshwater throughput, that is, the ecological capacity available in this region. In this way, we use the example of Yangzhou Prefecture, to account the main categories of human occupation of water ecosystem services. The result showed that there is a huge gap between the consumption and the supply of freshwater ecosystem services. This must encourage local government to make land-use and water management decisions both economically rational and environmentally sound.     

An novel identification method of the environmental risk sources for surface water pollution accidents in chemical industrial parks

The chemical industry is a major source of various pollution accidents. Improving the management level of risk sources for pollution accidents has become an urgent demand for most industrialized countries. In pollution accidents, the released chemicals harm the receptors to some extent depending on their sensitivity or susceptibility. Therefore, identifying the potential risk sources from such a large number of chemical enterprises has become pressingly urgent. Based on the simulation of the whole accident process, a novel and expandable identification method for risk sources causing water pollution accidents is presented. The newly developed approach, by analyzing and stimulating the whole process of a pollution accident between sources and receptors, can be applied to identify risk sources, especially on the nationwide scale. Three major types of losses, such as social, economic and ecological losses, were normalized, analyzed and used for overall consequence modeling. A specific case study area, located in a chemical industry park (CIP) along the Yangtze River in Jiangsu Province, China, was selected to test the potential of the identification method. The results showed that there were four risk sources for pollution accidents in this CIP. Aniline leakage in the HS Chemical Plant would lead to the most serious impact on the surrounding water environment. This potential accident would severely damage the ecosystem up to 3.8 km downstream of Yangtze River, and lead to pollution over a distance stretching to 73.7 km downstream. The proposed method is easily extended to the nationwide identification of potential risk sources.     

Occurrence and infection risk of waterborne pathogens in Wanzhou watershed of the Three Gorges Reservoir, China

The Three Gorges Reservoir (TGR), formed by China’s Yangtze Three Gorges Project, is the largest lake in the world, but there is too little information available about fecal contamination and waterborne pathogen impacts on this aquatic ecosystem. During two successive 1-year study periods (July 2009 to July 2011), the water quality in Wanzhou watershed of the TGR was tested with regard to the presence of fecal indicators and pathogens. According to Chinese and World Health Organization water quality standards, water quality in the mainstream was good but poor in backwater areas. Salmonella, Enterohemorrhagic Escherichia coli (EHEC), Giardia and Cryptosporidium were detected in the watershed. Prevalence and concentrations of the pathogens in the mainstream were lower than those in backwater areas. The estimated risk of infection with Salmonella, EHEC, Cryptosporidium, and Giardia per exposure event ranged from 2.9 × 10 -7 to 1.68 × 10-5 , 7.04 × 10-10 to 2.36 × 10-7 , 5.39 × 10-6 to 1.25 × 10-4 and 0 to 1.2 × 10-3 , respectively, for occupational divers and recreational swimmers exposed to the waters. The estimated risk of infection at exposure to the 95% upper confidence limit concentrations of Salmonella, Cryptosporidium and Giardia may be up to 2.62 × 10-5 , 2.55 × 10-4 and 2.86 × 10-3 , respectively. This study provides useful information for the residents, health care workers and managers to improve the safety of surface water and reduce the risk of fecal contamination in the TGR.     

Multi-indicator assessment of water environment in government environmental auditing

This study focused on a multi-indicator assessment methodology for governmental environmental auditing of water protection programs. The environmental status of Wuli Lake in China was assessed using the global indicators （driver-status-response） developed by the Commission on Sustainable Development, and four additional indicators proposed by the author： water quality, pollution load, aquatic ecosystem status, and lake sediment deposition. Various hydrological, chemical, biological and environmental parameters were used to estimate the values of the indicators for assessment of environmental status of the lake based on time series data sets for twenty years. The indicators proposed can be customized to meeting the needs for particular assessment of water protection programs. This method can be used to evaluate the performance of national environmental protection programs and provide technical support for environmental auditors.     

Changes in groundwater levels and the response of natural vegetation to transfer of water to the lower reaches of the Tarim River

Restoration and reconstruction of the degraded Tarim River ecosystem is an important challenge.A goal of an ecological water conveyance project is to protect and restore the natural vegetation in the lower reaches of Tarim River by transferring water from Bosten Lake,through the river channel,to the lower reaches.This study describes the changes in groundwater depth during the water transfer and the respondence of riparian vegetation to alterations in groundwater levels.The results indicate that groundwater depth along the Tarim River channel has a significant spatial-temporal component.Groundwater levels closest to the river channel show the most immediate and pronounced changes as a response to water transfer while those further away respond more slowly,although the observed change appears to be longer in duration.With a rise in the groundwater level,natural vegetation responded with higher growth rates,biomass and biodiversity.These favorable changes show that it is feasible to protect and restore the degraded natural vegetation by raising the groundwater depth.Plant communities are likely to reflect the hysteresis phenomenon,requiring higher water levels to initiate and stimulate desired growth than what may be needed to maintain the plant community.Because different species have different ecologies,including different root depths and densities and water needs,their response to increasing water availability will be spatially and temporally heterogenous.The response of vegetation is also influenced by microtopography and watering style.This paper discusses strategies for the protection and restoration of the degraded vegetation in the lower reaches of the Tarim River and provides information to complement ongoing theoretical research into ecological restoration in arid or semi-arid ecosystems.     

干旱区绿洲新疆石河子垦区地下水生态系统安全评价

为评价干旱区绿洲新疆石河子垦区的地下水生态系统安全状况,基于自然、生态、环境、社会和经济5个属性构建了地下水生态安全评价指标体系,运用主成分分析法和灰色关联分析方法筛选16个指标作为干旱区绿洲地下水生态安全评价指标,制定了适合于干旱区绿洲的地下水生态安全等级与评价标准,基于层次分析法和熵值法进行了指标权重分配,确定了各项评价指标在不同安全等级的隶属函数,应用模糊综合评判法对研究区内5个灌区的地下水生态安全状况进行评价.结果表明:①石河子灌区、金安灌区和玛纳斯灌区对基本安全级别的隶属度最高,分别为32.2%、35.4%和27.5%,3个灌区的地下水生态系统处于基本安全状态,区域面积占垦区总面积的51.8%;②莫索湾灌区地下水生态系统处于危机状态,相应的隶属度为27.2%,区域面积占垦区总面积的16.8%;③下野地灌区地下水生态系统处于不安全状态,相应的隶属度为28.8%,区域面积占垦区总面积的31.4%.研究显示,评价结果与实际情况基本相符,综合反映了该区域人类活动与地下水、生态系统的相互关系,证明了模糊综合评判法在干旱区绿洲地下水生态系统安全评价中具有一定的应用价值.      

基于景观结构和空间统计方法的绿洲区生态风险分析——以石羊河武威、民勤绿洲为例

论文以石羊河流域武威、民勤绿洲为研究区域,在ArcGIS 10.0、ArcView 3.2 软件和景观格局分析软件FRAGSTATS的技术支持下,采用干扰度指数、景观脆弱度指数、优势度指数和破碎度等指数,并通过分析景观格局与生态风险度之间的关系,将各景观指数进行栅格叠置运算,从而构建生态风险度,在此基础上,利用GIS局部空间统计方法研究分析了绿洲区景观结构格局和生态风险的时空变化特征及聚集模式。研究结果表明:① 城乡用地快速扩展的同时,耕地和草地景观有较大幅度的降低,优势景观类型由耕地、草地向耕地和建设用地转变;② 武威绿洲生态风险经历了从较高到中度的转变,生态风险整体趋于好转,而民勤绿洲生态风险从中/较高到较高/高变化,生态风险有所恶化;③ 武威绿洲主要为高于平均值的要素趋于聚集,表现为低生态风险小区高度聚集,且聚集度有上升的趋势,而民勤绿洲则主要为低于平均值的要素趋于聚集,高生态风险小区高度聚集,随着时间的推移呈现面积增大、空间扩展的态势。     

基于景观格局的干旱内陆河流域生态风险分析——以石羊河流域为例

合理评估流域生态风险,对于优化流域景观格局、建立流域生态风险预警机制、降低流域生态环境风险、维护流域生态功能具有十分重要的意义。文章以干旱内陆河典型流域为研究对象,以三期遥感数据为基础,构建生态风险指数,结合ArcGIS的空间分析功能,对流域生态风险的时空特征进行分析,结果表明：1987-2010 年,流域景观发生较大了变化,草地面积减少12.73×10⁴ hm²,未利用地面积增加15.59×10⁴ hm²;将生态风险划分为5 个等级,其中低生态风险区向流域上游不断迁移,面积减少31.89×10⁴ hm²,较低生态风险区向上游和中游不断延伸,面积增加29.30×10⁴ hm²,高生态风险区向下游不断扩展,面积增加58.69×10⁴hm²;流域生态风险转换方式共有7 种,低向高等级转化的总面积为122.56×10⁴ hm²,高向低等级转化的总面积为6.12×10⁴ hm²,生态风险呈增高趋势。     

近50 a塔里木河流域“四源”农业用水与干流生态系统结构变化关系研究

塔里木河源流区农业用水量直接影响下放至干流的水量,从而间接影响干流区生态系统结构的稳定性。为此,研究基于农业水足迹反映农业用水变化情况,进而分析塔里木河流域“四源”农业用水与干流生态系统结构变化的关系,为后续维护干流生态系统结构稳定性决策提供科学参考依据。结果表明：1960年代—1990年塔里木河“四源”农用地总量变化不大,阿克苏河流域新开垦量与叶尔羌河流域减少量相当,农业水足迹同时呈缓慢小幅增长,干流生态系统结构变化以自然绿洲生态系统缩小和荒漠生态系统扩张为主;以2000年为分界点,2000年之前“四源”农用地和农业水足迹显著增加,导致干流生态系统中自然水域生态系统、自然绿洲生态系统和荒漠生态系统皆有不同程度的萎缩,“四源”农业用水消耗是干流生态系统恶化的直接原因;2000年之后在生态治理工程的影响下,虽然“四源”农用地和总农业水足迹在持续增加,但是节水工程年均节约近27.22×10⁸ m³,保证了下游生态系统的需水量,使其得到一定恢复。     

饮马河流域水环境综合风险时空分布

为评价饮马河流域水环境综合风险,从水环境风险的危险性、暴露性、脆弱性及区域治理能力4个方面构建了饮马河流域水环境综合风险评估体系.选取2000年、2005年、2010年和2015年的水环境数据进行分析,采用水环境污染风险指数法和层次分析法对饮马河流域水环境综合风险进行评估,并绘制了各年度饮马河流域的风险空间分布图,分析了饮马河流域水环境风险空间变化特征.结果表明:2000—2015年,各危险性指标的量化值不断减小;暴露性指标中,耕地面积不断扩大,工业企业个数不断增加,人口密度变化不明显;各脆弱性指标的量化值不断减小;水环境区域治理能力各指标的量化值不断增大.研究显示,2000—2015年,流域内水环境危险性和脆弱性不断降低,暴露性和区域治理能力逐渐升高,水环境风险逐渐降低;其中,长春市一直处于水环境高风险水平,伊通县一直处于低风险水平.      

基于PSR的围圩养殖区湖泊湖荡群水生态系统健康评价

以典型围圩养殖区江苏省里下河腹部地区的41个湖泊湖荡为研究对象,分析筛选了围圩养殖对生态系统影响的主要指标,基于PSR方法评价了湖泊湖荡群的水生态系统健康状况.结果表明,选取的养殖面积占比、斑块密度及退圩还湖政策规划等指标能够有效反映区域的围圩养殖特色,全面表征围圩养殖对生态系统压力、状态、响应的影响.评价结果显示,里下河腹部地区41个湖泊湖荡中综合指数等级健康的占比4.9%,亚健康的占比87.8%,不健康的占比7.3%.研究结果可为围圩养殖区湖泊水生态系统健康评价、退圩还湖及水生态修复规划提供重要的技术方法.     

基于价值—风险的黄河上游生态功能区生态分区建设

黄河上游地区生态环境脆弱,水土流失和土地退化等生态环境问题不断威胁着生态系统健康与人居环境质量。为探究黄河上游生态功能区生态环境安全状况,本文基于2000年、2010年和2018年的土地利用数据,借助生态系统服务模型、生态风险模型,定量分析了生态系统服务价值和生态风险指数的时空演变规律,并通过Z-score标准化的方法建设了四类生态分区。结果表明：（1）研究期内,各土地利用类型均发生不同程度变化,其中建设用地由于耕地和草地的转入增加最显著,增长面积为118 km²,增长率为46.36%。（2）研究区总体服务价值变化程度较小,生态系统服务以调节服务为主且草地提供价值最高。高服务价值区主要分布于临夏州西南部和卓尼县等植被覆盖度较高的地区。（3）研究区生态风险水平总体偏低,整体呈现“南北两端高、中间低”的分布特征,其中低、较低生态风险区占总面积的76%以上。（4）四类生态分区均发生了较小的变化,表明生态分区处于较为稳定的发展状态。不同生态分区的空间分布连续性差,其中以高生态系统服务价值—高生态风险区（I）最为典型。通过生态系统服务与生态风险（价值—风险）建设生态分区,可为协调区域人地关系与明确未来发展方向提供理论基础。     

大宁河水生态系统健康评价

随着人口增长及社会经济的发展,河流水生态系统健康受到严重威胁.为了解大宁河水生态系统健康状况,选取大宁河2011-2015年水体水质[水温、pH、SD（透明度）、ρ（DO）、ρ（COD_Mn）、ρ（TN）、ρ（TP）]与水生态[藻密度、ρ（Chla）]9个主要指标,构建了大宁河水生态系统健康评价指标体系,运用基于熵值法的综合健康指数法对其水体生态系统健康状况进行综合评价.结果表明,2011-2015年,大宁河水生态系统健康状况整体呈亚健康状态,有50.89%的监测样本处于亚健康状态,枯水期健康状态好于丰水期.大宁河各监测断面CHI（综合健康指数）值的季节变化特征为丰水期低于枯水期;年际变化特征为从2011-2015年CHI值呈先升后降的变化趋势,健康状态呈先转好后转差的变化趋势,大宁河水体富营养化趋势明显;空间变化特征为丰水期和枯水期CHI最低值主要位于中下游的白水河、龙门和菜子坝断面,河流水质与人类活动强度密切相关.研究显示,影响大宁河水生态系统健康的关键因子为营养盐指标[ρ（TN）、ρ（TP）]和有机物指标[ρ（COD_Mn）].      

内陆河流域生态补偿标准问题研究——以石羊河流域为例

通过深入剖析生态补偿与社会区位条件以及自然区位条件的关系,从公平的角度出发,分析了石羊河各流域区位条件对补偿标准制定的影响,在此基础上,利用2009 年石羊河流域各地区基础数据,建立生态补偿标准计量模型,计算各流域不同植被类型补偿标准。研究结论如下：①合理补偿标准不仅需要考虑各生态系统的差异性,还必须保障补偿者的承担能力和满足受偿者的基本要求,同时合理制定补偿标准也是区域人与自然和谐发展的基本条件;②生态系统提供的生态服务和经济行为存在空间异质性,因此应建立差别化、动态化补偿标准;③利用区位差异条件可以科学地制定区域间生态补偿的分配标准,有效避免以往生态补偿政策制定中的“一刀切”现象。     

乡村旅游地生态系统安全评估研究——以岷江上游干温河谷区为例

以岷江上游干温河谷乡村旅游生态系统为研究对象,根据“压力一状态一响应”模型原理,运用构建的乡村旅游生态系统安全评估体系,在确定系统不安全指数和评价指标权重的基础上,评价乡村旅游生态系统的不安全度。研究表明,在羌族乡村旅游发展过程中,生态系统质量、生物物种质量、森林覆盖率等指标成为岷江上游干温河谷系统安全的重要限制因素,而生态建设能力和环境保护意识成为生态安全响应能力的主要限制因素。研究不仅为岷江干温河谷生态环境的人文治理途径提供借鉴,也将为震后羌族区域经济恢复与持续发展提供决策指导。