The social and ecological consequences of early cattle ranching in the Little Colorado River Basin

Commercial cattle ranching began in east central Arizona during the late 1880s when thousands of head of cattle were introduced onto the previously unexploited grasslands of the Little Colorado River Basin. Most of these animals were imported from western Texas where serious overgrazing had resulted in both catastrophic cattle losses and widespread range deterioration. By the turn of the century, the Texas experience had been repeated in Arizona, because Texas cattlemen continued to follow the same destructive stocking practices in this new region. This paper examines: (1) the early development of cattle ranching in the Little Colorado River Basin; (2) the various factors which contributed to overgrazing in the region; and (3) the consequences that commercial cattle ranching had on the local environment and on the pre-existing farming communities of the region.     

应用鱼类完整性评价体系评价辽河流域健康

根据2009年8月辽河流域33个站点采集的鱼类数据(参照点8个,观测点25个),通过参数指标值分布范围、相关关系和判别能力分析,从23个侯选指标中筛选出了辽河流域的鱼类完整性指数(F-IBI)构成指标体系。该体系包括鱼类总种类数、Shannon-Wiener多样性指数、中上层鱼类百分比、底层鱼类百分比、鱼类个体总数、杂食性鱼类百分比、耐受性鱼类百分比、敏感性鱼类百分比和产粘性卵鱼类百分比共9个生物参数。分别采用1、3、5赋值法和比值法计算各站点的IBI分值,并根据参照点IBI分值的25%分位数值确定健康等级标准,对小于25%分位数值的分布范围进行3等分,提出了辽河流域河流鱼类完整性评价标准,分为健康、一般、差、较差4个等级。两种方法评价结果虽不完全相同,但趋势基本一致。Pearson相关分析表明IBI值与生境状况、水质状况、栖息地环境质量显著相关,其中与海拔、栖息地评分呈显著正相关,与CODCr、氯化物、总溶解颗粒物、含沙量、硬度、电导率呈显著负相关。     

长江流域生态退捕渔民生计脆弱性评价及生计风险预测

渔民作为长江十年禁渔的参与主体,其后续生计发展将直接决定此生态保护政策的实施成效。在重构非自愿生态移民生计脆弱性评价体系的基础上,结合长江流域重点禁渔水域典型退捕渔民的抽样数据,测度渔民生计脆弱性指数(LVI)并找出影响后续生计恢复的主要障碍因子,最后跨领域的引入支持向量回归(SVR)预测模型动态分析了不同区域渔户生计脆弱性的演变趋势。结果表明:(1)渔民弃船上岸后呈现出生计脆弱性的比例较高,但不同类型区域间存在明显差异,其中内湖保护区最高,干流非保护区次之而干流保护区最低;(2)敏感性维度在诱发渔民生计脆弱性上起着主导作用,即个体禀赋比安置区条件更为重要,特别是成员年龄大但无基本社保兜底,受教育程度低且"双转"难的渔民家庭更易陷入生计困境;(3)自然和金融资本是推动渔民生计恢复的主要生计资本,而阻碍渔民生计脆弱性降低的共性因子主要有上岸后的收支失衡,社会支持不足及过分依赖原有生计方式等,同时各区域在脆弱性各维度上还有特殊的障碍因子;(4)推动安置区经济社会发展和家庭转产增收后,并不一定能确保缓解未来五年中的渔户生计脆弱性程度,上岸后完成社会融入并有效降低生产生活成本也至关重要,而干流保护区则还需加强人力资本建设,否则后续将面临极高的返贫风险;(5)长江临近区域的同类渔民生计脆弱性现状、面临的生计风险、后续生计恢复的进程具有一定的相似性和规律性,生计监测和帮扶政策可进行协同统筹。     

Water and community development in the Little Colorado River Basin

Water has historically been a critical limiting factor affecting community development throughout the American West. Within the Little Colorado River Basin of northeastern Arizona, abundant groundwater resources enabled local agricultural communities to overcome the limitations of unstable surfacewater sources. However, industrialization has led to sharp increases in groundwater consumption in the basin and to a decline in groundwater levels and/or quality at several locations. This paper examines the broader historical and regional implications of recent groundwater changes in the basin. Emphasis is placed upon the relationship between local developments and the rapid expansion of metropolitan centers in southern Arizona.     

基于格网的东江流域生态安全空间综合评价

通过统计以往关于生态安全评价的文献,从众多指标中筛选出应用频率较高的指标作为构建生态安全评价指标体系的基础,运用压力-状态-响应(P-S-R)模型,采用熵权法确定评价指标的权重,建立了基于格网的东江流域生态安全评价指标体系,并用综合评分法对东江流域的生态安全状况进行了评价。结果表明:东江流域生态安全由2000年的较安全等级下降为2004年的较不安全等级,到2008年改善为很安全等级。可见,基于对照比较筛选以确定生态安全评价指标,可在很大程度上克服目前生态安全评价指标体系缺乏统一标准的不足;基于格网的生态安全评价,可消除行政界线变动带来的影响,并可反映区域内部的空间差异性,从而提高了研究结果的可信度。     

黄河流域青海片生态承载力动态评价

采用基于生态系统健康的生态承载力评价模型与方法,研究了黄河流域青海片生态承载力的动态变化。结果表明:生态承载力指数随时间的推移呈下降趋势,由1985年的0.5096降至1999年的0.4700和2015年的0.4263;黄河流域青海片生态系统健康等级较低,多处于亚健康状态或不健康状态;空间上,以湟水流域和黄河干流区域生态系统健康等级最低;各项分指数中,以资源环境承载力指数相应的生态系统健康等级最高,多处于健康状态;人类潜力和生态弹性力是制约黄河流域青海片生态系统健康的主要因素。     

Distribution,habitat and conservation status of desert pupfish (Cyprinodon macularius) in the Lower Colorado River Basin,Mexico

In order to better determine the currentstatus of desert pupfish populations (Cyprinodon macularius macularius) in the LowerColorado River Basin of Mexico, bimonthly fishsampling and habitat evaluations were carriedout from September 1996 to August 1997 in sixlocalities of Baja California and Sonora.Desert pupfish were collected using minnowseines and traps. Four sampling sites are inSonora, in shallow marginal habitats of theCiénega Santa Clara (Hunters' Camp, Outletof the Welton-Mohawk channel, El Doctor andFlor del Desierto) and two are in BajaCalifornia (Cerro Prieto and streams south ofCerro Prieto). The most abundant fish speciessampled was native desert pupfish (C.macularius, 59%) followed by sailfin molly(Poecilia latipinna, 19%), redbellytilapia (Tilapia cf. zilli, 10%) and western mosquito fish (Gambusiaaffinis, 7%). Significant temporalfluctuations in distribution and abundance ofdesert pupfish populations, as previouslyreported for these populations, was againdocumented. The main anthropogenic factorsaffecting distribution and abundance of desertpupfish populations in the Mexican portion ofthe Lower Colorado River Basin are progressivealteration of aquatic and riparian habitats, aswell as presence of exotic fishes that havecaused the displacement or elimination ofnative fish populations. Both habitat andpresence of the desert pupfish populations inthe study area are controlled by theperiodicity, quality and volume of dischargesinto the Mexican portion of the basin from theUnited States.     

基于土地利用变化的玛纳斯河流域景观生态风险评价

摘要：随着人类活动范围日益扩张和强度增加,景观生态风险评价已经成为预测和衡量生态环境质量和动态演化的重要手段。本文以玛纳斯河流域（简称玛河流域）为研究区,选取2000、2005、2010和2015年4期Landsat TM/ETM遥感影像,运用ENVI软件对研究区土地利用类型进行解译,定量分析流域近15年来土地利用动态变化特征,基于景观格局指数,采用地统计学方法,探究玛河流域景观生态风险程度及时空分异特征。结果表明：（1）2000—2015年,玛河流域景观格局发生了较大变化,耕地景观面积增加最多（2638.31 km^2）,主要由草地和未利用地转入;未利用地景观面积减少最多（2559.99 km^2）,主要转化成了草地、耕地和林地;（2）将流域景观生态风险划分为5个等级,研究期内流域低、中风险区面积增加而较高、高风险区面积减少,整体景观生态风险指数减小,所以研究区生态环境在整体上呈现好转;（3）2000—2005年、2010—2015年玛河流域在景观风险分布格局上发生较小变化,但2005—2010年流域景观风险分布格局发生较大变化,主要是中、较高和高风险区向流域南北方向分散并转移,低风险区向流域北部转移。     

基于景观生态风险评价的涪江流域景观格局优化

以流域为尺度进行景观生态风险评价以及景观格局优化,有利于为流域生态系统服务的提高和人类活动管控提供科学依据。以涪江流域为研究区域,从"自然-社会-景观格局"3个维度选取10个评价因子建立评价指标体系,采取空间主成分分析法（SPCA）对流域景观生态风险进行综合评价,再基于生态风险评价的结果和生态源地利用最小累积阻力模型（MCR）和网络分析等方法实现流域景观格局优化。研究结果表明：①涪江流域景观生态风险等级在空间分布上呈西北部高于东南部地区,主要是受自然和景观格局因子影响较大。②涪江流域所面临的生态风险问题较为严重,生态风险等级为中度及以上的区域面积总和为25596.51 km²,占研究区总面积比例的65.35%。③生态源地以林地和水域为主,面积为11194.28 km²,占流域总面积比例为25.58%。④构建生态廊道共41条,总长度为5229.04 km,其中原有廊道29条,新添廊道12条,提取生态节点53个;利用网络分析形成了以主廊道为"中轴",构建的生态廊道为"辅助",提取的生态节点为"枢纽"的较为完整的网络生态结构。对研究区景观格局优化前后的连通度进行对比,优化后的整体景观格局连通度得到较大幅度提升。     

A dynamic assessment of water scarcity risk in the Lower Brahmaputra River Basin: An integrated approach

Many international river basins are likely to experience increasing water scarcity over the coming decades. This water scarcity is not rooted only in the limitation of resources, i.e. the shortage in the availability of freshwater relative to water demand, but also on social factors (e.g. flawed water planning and management approaches, institutional incapability to provide water services, unsustainable economic policies). Therefore, the assessment of water scarcity risks is not limited to the assessment of physical water supply and demand, but it requires also consideration of several socio-economic factors. In this study, we provide a comprehensive dynamic assessment of water scarcity risks for the Lower Brahmaputra river basin, a region where the hydrological impact of climate change is expected to be particularly strong and population pressure is high. The basin area of Brahmaputra River lies among four different countries: China, India, Bangladesh and Bhutan. For water scarcity assessment, we propose a novel integration of different approaches: (i) the assessment of water scarcity risk, considering complex social-ecological system; (ii) the analysis of dynamic behaviour of the system; (iii) exploration of participatory approach in which limited number of stakeholders identify the most relevant issues with reference to water scarcity risks and provide their preferences for the aggregation of risk assessment indicators. Results show that water scarcity risk is expected to slightly increase and to fluctuate remarkably as a function of the hazard signal. Social indicators show trends that can at least partially compensate the increasing trend of the drought index. The results of this study are intended to be used for contributing to planned adaptation of water resources systems, in Lower Brahmaputra River Basin.     

A fish-based index for the assessment of the ecological quality of temperate lakes

A fish – based index for the assessment of the ecological quality of natural temperate lakes was developed, in accordance to the requirements of the Water Framework Directive (WFD) 2000/60/EC. As a case study, 11 natural lakes located at northern and western Greece were selected. Fish surveys were conducted during mid summer to mid autumn in 2010, 2011 and 2012 using Nordic gillnets and electrofishing. Environmental parameters and anthropogenic pressures were assessed for each lake. Fish species richness, abundance, trophic, reproductive and habitat functional guilds were used for extracting a set of 107 metrics, meeting the requirements of the WFD. All metrics were initially tested as candidates for the index development. A stepwise linear regression of each metric against environmental parameters (lake area, altitude, maximum depth, alkalinity) and anthropogenic pressures (drainage area covered by non-natural land uses – NNLC, water total phosphorus concentrations – TP, Lake Habitat Modification Score – LHMS) was initially conducted for ensuring pressure-response relationships. Reference conditions for each lake were estimated by the hindcasting procedure and the ecological quality for each lake was expressed as the ecological quality ratio (EQR) by a value ranging from 0 (poor quality) to 1 (excellent quality). Two fish fauna metrics, the relative numerical abundance of introduced species (Introduced_a) and the relative biomass of omnivorous species (OMNI_b) were finally extracted as the most significant, responding to LHMS and TP, respectively. The final index was expressed as the mean values of the EQRs of these two metrics. The multimetric fish index presented herein could serve as a tool for assessing the ecological quality of natural lakes at broad geographical scale and generally, in the Mediterranean temperate lakes with similar hydromorphological characteristics.     

基于生态风险评估的锡林河流域退化草地优化管理

利用遥感监测和空间信息分析技术,通过对退化草地的退化等级评估、风险度评估以及易恢复度评估,构建了草地生态优化管理指数(EMI),探讨了退化草地生态优化管理的实践途径;并以锡林河流域为例, 分析了退化草地生态优化管理指数.结果表明,通过构建退化草地优化管理模型,定量分析流域内不同优化管理等级退化草地的退化程度、危害性和易恢复性,可以有针对性地采取合理的治理措施,有利于退化草地治理中的资源优化配置.该模型能整合退化草地的各种相关信息,具有较强的普适性.     

基于SPCA和遥感指数的干旱内陆河流域生态脆弱性时空演变及动因分析——以石羊河流域为例

以石羊河流域为研究区,基于干旱内陆河流域生态特征和遥感数据快速、客观、大面积观测的特点,采用遥感模型计算湿度、绿度、干度和热度等指标,并构建石羊河流域生态脆弱性评价指标体系,在此基础上运用空间主成分分析法(SPCA)对石羊河流域2000和2016年生态脆弱性时空演变及动因进行了分析。研究结果表明:(1)从各遥感指数空间分布来看,湿度和绿度指标均值在17年间呈增长趋势,证明该流域水源涵养能力变好,植被覆盖率变大;干度指标均值有所下降,表明该流域地表裸露程度有所降低;而与植被和水资源关系密切的地表温度均值呈逐年上升趋势,说明该流域水热平衡差异进一步增加,对未来生态脆弱性影响显著;(2)从全流域生态脆弱性时空演变特征来看,该流域主要以强度和中度脆弱为主,17年间生态脆弱性整体上呈缓慢降低趋势;(3)从不同的海拔生态脆弱性分布来看,中山区(1000—2000m)最高,高中山区(2000—3000m)次之,高山区(3000m)最低,17年间中山区生态脆弱性有所下降,而高中山区与高山区却呈上升的趋势;(4)从不同的行政区划生态脆弱性来看,金川区、凉州区、永昌县、民勤县和古浪县整体上处于中度和强度脆弱水平,而天祝县和肃南县处于轻度和微度脆弱水平;(5)从生态脆弱性的演变动因来看,4个指标对石羊河流域生态脆弱性影响均为显著。2000年生态脆弱性的主导影响因子依次为热度湿度绿度干度,而2016年为热度干度绿度湿度。总的来看,石羊河流域生态脆弱程度近年来有所降低,但综合治理工作仍任重道远。本文的遥感方法和分析思路对该流域生态脆弱性保护及治理提供一定的理论基础和决策依据。     

Condition status of the endangered desert pupfish,Cyprinodon macularius Baird and Girard, 1853, in the Lower Colorado River Basin (Mexico)

The length‐weight relationship (LWR) was used to test differences in the fish somatic condition factor among four populations of the endangered desert pupfish, Cyprinodon macularius, from the Lower Colorado River Basin, Mexico. Bimonthly fish sampling and habitat assessments were carried out from September 1996 to August 1997 for four sites in Baja California and Sonora. Slope b of the WLR varied from 3.238 (Cerro Prieto population) to 3.613 (Welton‐Mohawk population), showing in all populations a positive allometric growth. Male b values were higher than those of females for Cerro Prieto (3.303 vs 3.071), Welton‐Mohawk (3.866 vs 3.579), and Flor del Desierto (3.357 vs 3.169) populations. The Cerro Prieto population showed the highest somatic condition (y‐intercept, a = ?11.759). Water depth and salinity were the ecological variables that better accounted for most of the variation in the somatic condition of this pupfish, with a negative and a positive effect, respectively.     

基于改进遥感生态指数的宁夏沿黄平原区生态环境质量评价

区域生态环境质量评价是国民经济建设与可持续性发展规划的基础，是生态学研究的主要方向之一。以土地利用/覆盖数据和Landsat OLI数据为基础，分别在ArcGIS和GEE平台上进行景观多样性指数（Landscape Diversity Index，LDI）与归一化植被指数（Normalized Difference Vegetation Index，NDVI）、湿度（Wet Index，WI）、归一化裸土和建筑指数（Normalized Difference Building-Soil Index，NDBSI）、遥感生态指数（Remote Sensing Based Ecological Index，RSEI）和改进遥感生态指数（Modified Remote Sensing Ecological Index，MRSEI）的计算。在LDI最佳尺度约束下分析表明，宁夏沿黄平原区景观多样性指数具有显著尺度依赖特征（P<0.001），阈值出现在3000 m×3000 m。主成分分析（Principal Component Analysis，PCA）解释了研究区改进遥感生态指数主要受到NDVI和LDI影响，其中NDVI是PC1（特征值贡献率68.98%）的决定因子，特征向量为0.8901；LDI为次要决定因子，特征向量为-0.4146，该分量在MRSEI计算中分值较高。LDI是PC2（特征值贡献率28.76%）的决定因子，特征向量为0.9100；NDVI为次要决定因子，特征向量为0.4056，该分量在MRSEI计算中分值较低。从MRSEI在应用中可信性来看，其在分析中采用LDI替代LST有效地避免了RSEI分析中NDBSI和LST之间存在的生态学意义重复表达和多因子向量投影中的高度聚集。研究区空间异质性主要以"差"和"较差"级别分布在不同土地利用/覆盖类型交错区且以环绕研究区为主要特点。在"差"到"好"梯度上，斑块密度为减少趋势由8.3个/km²减少到5.9个/km²，而平均斑块面积呈增加趋势由0.120 km²增加到0.169 km²。综合来看宁夏沿黄平原区生态环境质量总体MRSEI值为0.0117刚好超过"较好"水平下限。