Identifying potential conservation areas in the Cuitzeo Lake basin,Mexico by multitemporal analysis of landscape connectivity

Lake Cuitzeo basin is an important ecological area subjected to strong human pressure on forest covers that are key elements for the long-term support of biodiversity. We studied landscape connectivity changes for the years 1975, 1996, 2000, 2003 and 2008 to identify potential conservation areas in the basin. We modeled potential distributions of the Mexican bobcat (Lynx rufus escuinapae) and the ringtail (Bassariscus astutus) – two terrestrial mammal focal species with contrasting dispersal capacities – and we determined their habitat availability and suitability in the basin. We then identified their optimal habitat patches and produced landscape cumulative resistance maps, estimated least-cost paths (graph theory approach), and elaborated current flow maps (circuit theory approach). For evaluation of landscape connectivity, we applied an integral index of connectivity (IIC) to each study period, and determined individual habitat patch contribution to the overall landscape connectivity. The IIC index had very low values associated with reduced availability of focal species habitat. However, our study showed the conservation importance of the surface of optimal habitat patch areas. The combined application of a graph-based approach and current flow mapping were useful, and complementary both in terms of estimating potential dispersal corridors and identifying high probability dispersal areas. This indicated that landscape connectivity analysis is a useful tool for identification of potential conservation areas and for local landscape planning.     

鸭绿江河口湿地鸟类生境的破坏与修复

鸭绿江河口湿地国家级自然保护区共发现鸟类210种,目前只是在核心区才保留有少许的自然生境--黑嘴鸥(Larus saundersi)的巢址,生境破碎化、片段化现象严重.文章运用景观生态学、恢复生态学、保护生物学的原理和方法、兼顾保护与发展,遵循可持续发展的基本思想,进行生境修复,加强生态管理,使得鸭绿江河口湿地真正成为众多鸟类迁徙路上理想的歇脚地、加油站.     

Use of seasonal freshwater wetlands by fishes in a temperate river floodplain

This study examined the use of freshwater wetland restoration and enhancement projects ( i.e . non-estuarine wetlands subject to seasonal drying) by fish populations. To quantify fish use of freshwater emergent wetlands and assess the effect of wetland enhancement ( i.e . addition of water control structures), two enhanced and two unenhanced emergent wetlands were compared, as well as two oxbow habitats within the Chehalis River floodplain. Eighteen fish species were captured using fyke nets and emigrant traps from January to the beginning of June, with the most abundant being three-spined stickleback Gasterosteus aculeatus and Olympic mudminnow Novumbra hubbsi . Coho salmon Oncorhynchus kisutch was the dominant salmonid at all sites. Enhanced wetlands, with their extended hydroperiods, had significantly higher abundances of yearling coho salmon than unenhanced wetlands. Both enhanced and unenhanced emergent wetlands yielded higher abundances of non-game native fishes than oxbow habitats. Oxbow habitats, however, were dominated by coho salmon. Fish survival in the wetland habitats was dependent on emigration to the river before dissolved oxygen concentrations decreased and wetlands became isolated and stranding occurred. This study suggests that wetland enhancement projects with an outlet to the river channel appear to provide fishes with important temporary habitats if they have the opportunity to leave the wetland as dissolved oxygen levels deteriorate.     

Grazing with Galloway cattle for floodplain restoration in the Syr Valley, Luxembourg

Three years after a river restoration scheme in the Syr Valley (Luxembourg) we investigated habitat development and habitat use of Galloway cattle deployed in a low-intensity grazing system on a permanent floodplain pasture. Habitats were delimited with a mobile GPS/GIS mapping system and their spatial development was assessed over three consecutive years. During these three years, the patches of the six habitats decreased to 40% of mean initial size, and a rapid net area expansion of wetland habitats (large sedge swamps: +100%, marsh and tall forb grasslands: +43%) was observed. The behavioural patterns and grazing preferences of the cattle were observed directly during the vegetation period in June, August and November. These observations were complemented by a transect analysis of cattle impact indicators in June and November. The cattle grazed the different habitats very selectively, as they preferred the mesophilic, and ruderal grasslands 1.6, and 5.6 times more than expected respectively. During the growing season, the grazing niche breadth declined (3.92 in June to 2.68 in November), and less preferred forage habitats like large sedge swamps were grazed primarily in the autumn. We used bite and step rates to investigate grazing intensity by habitat type. During summer, grazing intensity correlated with forage quality in the different habitat patches, whereas in autumn it was obviously influenced by the effort required to access the desired forage plants in a given habitat. The impact indicators revealed a matter transfer from riparian areas to the valley edge. Here, we give a first insight into habitat development and habitat use of Galloway cattle in a recently restored floodplain area and derive recommendations for the adaptive management of future projects.     

Aquatic invertebrate assemblages as potential indicators of restoration conditions in wetlands of Northeastern China

Wetland restoration has been implemented widely but evaluation of the effectiveness of wetland restoration has been limited. In this study, we aimed to investigate the utility of aquatic invertebrate assemblages as potential indicators of restoration condition in wetlands of the Sanjiang Plain, Northeastern China. Results from non‐metric multidimensional scaling analysis of invertebrate assemblages showed that study wetlands (n = 16) divided into two groups: natural wetlands and wetlands that have been restored for 4 years were classified as a group, and impaired wetlands and wetlands restored for only 1 year were classified into another group. After 4 years of recovery, 47.9% of invertebrate taxa found at the natural wetlands could also be found at the restored wetlands, primarily insects with aerial dispersal capabilities for rapid colonization. Indicator species analysis identified differences in community composition among wetland types, and Amphiagrion sp. and Bezzia sp. were indicators of the restored wetlands. In Northeastern China, aquatic invertebrate assemblages and certain indicator species may provide robust measures of wetland restoration. It is urgent for further exploration to monitor restored wetlands in the long‐time series and fully assess the efficiency of the restoration.     

上海大莲湖湖滨带湿地的生态修复

采用改变土地利用模式、水系改造和植被配置等技术开展了上海青浦大莲湖湿地修复示范工程。本文从2008年8月到2010年3月跟踪调查了土地利用方式、鸟类群落、两栖爬行类、水质等多类指标来对示范工程进行评估。结果表明,实验区生态系统的生境结构和生物多样性组成都发生了明显的变化。实验区内土地利用由主要以人工养殖鱼塘和林地为主的人工湿地(人工鱼塘占50%,林地占25%),转变为以开放性水域和乔灌草相结合的半自然状态下的自然湿地(明水面面积占30%,各类植被群落占50%,人工鱼塘完全消失),植被从只有片段化林地转变为乔木、灌木丛、草本植物及各类水生植物相结合的格局;工程后鸟类种类和数量均高于工程前(新纪录到11种鸟类),鸟类多样性指数和均匀性指数也有明显增加,其中目标鸟类——雁鸭类新增6种,种类和数量都呈显著增加;两栖爬行类种类变化不大,共记录到6科12种,但整体数量比工程前增长了59.1%;水质指标的变化也很突出,与工程前人工鱼塘相比,实验区内水体中总氮(TN)、硝态氮(NO3-N)、总磷(TP)、叶绿素a(Chla)、高锰酸钾指数(CODMn)等主要指标均有显著下降(P<0.05),水质改善显著。由此说明,修复工程改善了大莲湖湖滨带湿地的生态环境,生物多样性得到较好的恢复,呈现出良好的湿地修复效果。     

丛枝菌根在煤矿区生态重建中的应用

煤炭开采在促进国民经济快速发展的同时,引发诸多生态环境问题,分别就矿区生态治理中存在的主要障碍因子进行论述,结合丛枝菌根对宿主植物的营养吸收和抗逆性能,综述了丛枝菌根在矿区生态重建中应用的研究进展,揭示出菌根应用在矿区生态重建中的作用潜力和研究方向,极大地提高了矿区生态恢复的质量。     

Development of an in-stream migration model for Gammarus pulex L. (Crustacea, Amphipoda) as a tool in river restoration management

Ecological models can act as interesting tools to support decision-making in river restoration management. In particular models which are capable of predicting the habitat requirements of species are of considerable importance to ensure that the planned actions have the desired effects on the aquatic ecosystem. To this end, Artificial Neural Network (ANN) models were tested and optimized for the prediction of the habitat suitability for Gammarus pulex, a relevant indicator species in water quality assessment. Although ANN models are in general quite robust with a rather high predictive reliability, the model performance had to be increased with regard to simulations for river restoration management. In particular, it has been shown that spatial and temporal expert-rules could possibly be included. Migration dynamics of downstream drift and upstream migration of the organisms and migration barriers along the river (weirs, culverted river sections,␣...) might indeed deliver important additional information on the effectiveness of the restoration plans, and also on the timing of the expected effects. In this context, an additional in-stream migration model for Gammarus pulex was developed. This migration model, implemented in a Geographical Information System (GIS), has been used to simulate a practical river restoration scenario for a river in Flanders, Belgium. The case study illustrated that the removal of a weir, at a particular site, resulted in the improvement of the habitat suitability for Gammarus pulex. The ANN models predicted that after restoration the habitat was suitable again for Gammarus pulex. The migration model indicated that the restored parts of the river would be recolonized within about 2 months. In this way, decision makers can have an idea whether and when a restoration option will have a desired effect.     

半干旱区生态恢复关键生态系统识别——以内蒙古自治区和林县为例

我国土地退化严重,且大部分发生在干旱半干旱地区.恢复为何种生态系统类型是生态学研究的重要课题.采用生态功能区划,根据各个生态功能区主体生态系统功能,推导发挥此功能的生态系统类型的方法,识别关键生态系统类型.以内蒙古自治区和林县为例,采用文献调研、实地调查、3S技术等方法,在评价该县生态敏感性、生态服务功能重要性的基础上,将该县划分为3个一级生态区,11个二级生态功能区.根据各个生态功能区的主体生态系统服务功能,分析发挥该功能的可能生态系统类型.再根据全国自然植被区划、气候变化趋势模型以及现状植被类型,识别各个生态功能区的关键生态系统类型.     

Biogeochemical response of organic-rich freshwater marshes in the Louisiana delta plain to chronic river water influx

To help evaluate effects of Mississippi River inputs to sustainability of coastal Louisiana ecosystems, we compared porewater and substrate quality of organic-rich Panicum hemitomon freshwater marshes inundated by river water annually for more than 30 years (Penchant basin, PB) or not during the same time (Barataria basin, BB). In the marshes receiving river water the soil environment was more reduced, the organic substrate was more decomposed and accumulated more sulfur. The porewater dissolved ammonium and orthophosphate concentrations were an order of magnitude higher and sulfide and alkalinity concentrations were more than twice as high in PB compared with BB marshes. The pH was higher and dissolved iron concentrations were more than an order of magnitude lower in PB marshes than in BB marshes. The influx of nutrient-rich river water did not enhance end-of-year above-ground standing biomass or vertical accretion rates of the shallow substrate. The differences in porewater chemistry and substrate quality are reasonably linked to the long-term influx of river water through biogeochemical processes and transformations involving alkalinity, nitrate and sulfate. The key factor is the continual replenishment of alkalinity, nitrate and sulfate via overland flow during high river stage each year for several weeks to more than 6 months. This leads to a reducing soil environment, pooling of the phytotoxin sulfide and inorganic nutrients in porewater, and internally generated alkalinity. Organic matter decomposition is enhanced under these conditions and root mats degraded. The more decomposed root mat makes these marshes more susceptible to erosion during infrequent high-energy events (for example hurricanes) and regular low-energy events, such as tides and the passage of weather fronts. Our findings were unexpected and, if generally applicable, suggest that river diversions may not be the beneficial mitigating agent of wetland restoration and conservation that they are anticipated to be.     

A rapid ecological network assessment tool and its use in locating habitat extension areas in a changing landscape

An understanding of the ecological systems which dictate landscape form and function must be achieved in order to objectively view development led landscape ecological change. Habitat fragmentation, loss and isolation of habitat patches and reduced connectivity are having a significant detrimental effect on the way our landscapes function. A conservation planning tool which considers these issues in tandem with planned landscape level change, whilst incorporating species and habitat specific details, is necessary if we are to ameliorate the ecological impact of built development.A landscape scale modelling approach was developed for a case study area in the South Midlands of the UK to investigate spatial targeting of habitat extension areas. Habitat extension opportunities currently arise as a consequence of existing planning regulations and conditions and are likely to increase as the concept of habitat “banking” is embraced. Ecological networks and ecoprofiles were employed to guide the location of these extension areas via an examination of the landscape ecology effects of area composition, size and location. The ability of extension areas to contribute to landscape functionality was determined spatially. Habitat extension areas identified by the approach increased the existing ecological network size by a factor of over 2.7:1 and were able to deliver the majority of habitat creation targets set out in regional Biodiversity Action Plans (BAPs). 100% of wetland, unimproved grassland and broadleaf and mixed woodland creation targets were met, whilst 75% of the lowland heath target could be achieved. Semi-natural habitat mosaic areas of over 3700 ha which incorporated habitat of more than one type were identified, with such areas determined to be of importance in achieving landscape improvements for a wide range of species. We conclude that rapid assessment tools such as that employed in this research will have increased utility in conservation planning as the British landscape continues to experience both sustained and elevated levels of built development pressure.     

Potential biodiversity map of bird species (Passeriformes): Analyses of ecological niche,environmental characterization and identification of priority conservation areas in southern Patagonia

Different methodologies try to identify priority conservation areas (PCA) to improve habitat conservation and decrease human pressures over bird species at coarse-scale. Map of potential biodiversity (PB) can identify PCA (high PB values) at different scale levels by considering ecological requirements and distributions through potential habitat suitability (PHS) models. The aim was to elaborate a map of PB of bird species based on PHS models to spatially identify PCA in Santa Cruz, Argentina. Moreover, we want to analysis species’ ecology requirements, and evaluate PB values and spatially identify PCA through two scale levels. We computed 47 models using Environmental Niche Factor Analysis (ENFA) on Biomapper software. Each model was visualized and combined to get a unique map of PB. We analyzed ecological requirements by specialization and marginality and PHS maps. Moreover, considering natural environments (regional level) and forest types’ cover (forest landscape level), we evaluated PB values using ANOVAs and identified PCA under different human pressures, using human footprint (HPF) map. Bird species related to Nothofagus forests were most specialist and exhibited a narrower potential distribution than grassland species. At regional level, Magellanic grass steppes displayed the highest PB values, where most of the PCA had high HPF values. At forest landscape level, ecotone N. antarctica forests had the highest PB values, where PCA with low HFP values were outside current protected networking. We conclude that combining PHS models and the map of PB allowed us to improve bird distribution studies and to assist biodiversity conservation strategies under human pressures.     

Stream channel restoration increases climate resiliency in a thermally vulnerable Appalachian river

We quantified stream temperature response to in‐stream habitat restoration designed to improve thermal suitability and resiliency of a high‐elevation Appalachian stream known to support a temperature‐limited brook trout population. Our specific objectives were to determine if: (1) construction of deep pools created channel unit‐scale thermal refugia and (2) reach scale stream channel reconfiguration reduced peak water temperatures along a longitudinal continuum known to be highly susceptible to summer‐time warming. Contrary to expectations, constructed pools did not significantly decrease channel unit‐scale summer water temperatures relative to paired control sites. This suggests that constructed pools did not successfully intercept a cool groundwater source. However, we did find a significant effect of stream channel restoration on reach‐scale thermal regimes. Both mean and maximum daily stream temperatures experienced significantly reduced warming trends in restored sections relative to control sections. Furthermore, we found that restoration efforts had the greatest effect on stream temperatures downstream of large tributaries. Restoration appears to have significantly altered thermal regimes within upper Shavers Fork, largely in response to changes in channel morphology that facilitated water movement below major cold‐water inputs. Decreased longitudinal warming will likely increase the thermal resiliency of the Shavers Fork main‐stem, sustaining the ability of these key large river habitats to continue supporting critical metapopulation processes (e.g. supplemental foraging and dispersal among tributary populations) in the face of climate change.     

基于Logistic回归模型的黄河三角洲淡水恢复湿地大型底栖生物种群分布模拟

掌握大型底栖生物种群分布的时空变化对正确把握湿地生态修复效率、揭示湿地生态演替过程具有重要理论与实践意义。选择黄河三角洲地区一千二自然保护区的淡水恢复湿地为研究区,在2014—2015年大型底栖生物野外采样和优势物种的基础上,选择了琥珀刺沙蚕、中华蜾蠃蜚、摇蚊幼虫作为典型优势物种,构建了基于Logistic回归的淡水恢复湿地大型底栖生物种群分布模拟模型。其中,琥珀刺沙蚕和摇蚊幼虫的模拟结果较好,模拟准确率分别为84.9%和77.9%,而中华蜾蠃蜚的模拟结果不甚理想。对比生态补水前后大型底栖生物的模拟分布结果发现,琥珀刺沙蚕主要集中在潮间带区域,且在春、秋两季的生存概率分布差异不显著;而淡水恢复湿地中摇蚊幼虫的分布概率显著提高,其中高于分割值0.5的栖息面积增长了9.9—10.8倍,表明退化湿地生境正处于向淡水湿地演替进程中。     

基于生态安全格局的山水林田湖草生态保护修复优先区识别——以四川省华蓥山区为例

优先区识别,是科学有序推进山水林田湖草生态保护修复工作的重要基础。以山水林田湖草生态保护修复工程之一的四川华蓥山区为例,基于生态系统服务重要性提取生态源地共1392.63 km²,占华蓥山区总面积的35.60%;结合土地覆被类型与地质灾害敏感性构建生态阻力面,并利用最小累积阻力模型与电路模型提取生态廊道共84条,夹点区域0.1 km²,含夹点廊道10条;生态保护优先区主要分布在景观破碎化较为严重的广安区境内,以及华蓥山西南端的夹点廊道。以生态修复模拟方法识别障碍点,确定生态修复优先区93.86 km²,大致分两片。其中,广安区境内受到人类活动干扰的破碎化生态空间,主要生态修复策略为植被恢复与退耕还林;华蓥山、铜锣山、明月山等滑坡、泥石流地质灾害频发区,主要生态修复策略是矿山地质修复与植被恢复。本研究提出生态安全格局构建与生态修复模拟的思路,为山水林田湖草生态保护修复工作提供了可行的定量方法。     

Consistent trophic patterns among fishes in lagoon and channel habitats of a tropical floodplain river: Evidence from stable isotopes

The relationship between food web dynamics and hydrological connectivity in rivers should be strongly influenced by annual flood pulses that affect primary production dynamics and movement of organic matter and consumer taxa. We sampled basal production sources and fishes from connected lagoons and the main channel of a low-gradient, floodplain river within the Orinoco River Basin in Venezuela. Stable isotope analysis was used to model the contribution of four basal production sources to fishes, and to examine patterns of mean trophic position during the falling-water period of the annual flood cycle. IsoSource, a multi-source mixing model, indicated that proportional contributions from production sources to fish assemblages were similar in lagoons and the main channel. Although distributions differed, the means for trophic positions of fish assemblages as well as individual species were similar between the two habitats. These findings contradict recent food web studies conducted in temperate floodplain rivers that described significant differences in trophic positions of fishes from slackwater and floodplain versus main channel habitats. Low between-habitat trophic variation in this tropical river probably results from an extended annual flood pulse (ca. 5 mo.) that allows mixing of sestonic and allochthonous basal production sources and extensive lateral movements of fishes throughout the riverscape.     

万宁市小海红树林生境适宜性评价及修复分析

【目的】定量分析评估复杂环境条件与红树林分布特征之间的交互作用,探索一定区域尺度上红树林生境适宜性及适生区空间分布格局。【方法】以万宁市小海为研究区,选取水文动力、水质底质、地形高程3个大类环境变量,通过层次分析法搭建评价结构模型,结合德尔菲法获得各指标权重,并将各环境指标经归一化处理后基于GIS技术获取小海红树林适生区的空间分布。【结果】影响小海红树林生长分布的主要环境变量为水深高程、潮位、潮差、盐度等因子;研究区港北口门附近区域红树林生境适宜性较高,面积约121.6 hm²;西南侧及东南侧区域适宜性适中,面积约328.5 hm²;南侧及中间部分区域适宜性较低,面积约137.2 hm²。【结论】小海区域的气候、水质和水文动力条件均较适宜红树林存活、生长,相当一部分清退的养殖塘具备红树林种植修复的基本生态条件,但需进行生境改造,并依据生态位原理合理搭配红树物种,以期达到修复效果。     

Assessing the effect of EWDP on vegetation restoration by remote sensing in the lower reaches of Tarim River

In this study, effect of ecological water diversion on vegetation restoration in the lower reaches of Tarim River is assessed by coupling remote sensing techniques and a field-based survey. Land use/cover and fractional vegetation coverage (Fvc) maps derived from remote sensing images, ground validation data, and hydrological observation data are adopted to analyze the responses of Ecological Water Diversion Project (EWDP). The results indicate that, the EWDP has showed a positive effect on vegetation restoration in the lower part of Tarim Basin. During 2001 to 2013, transformation from unused land to nature vegetation (i.e. forest land, grassland and scrubland) was the major process of land use/cover change; the area of natural vegetation showed a 4.7% increase, and the area of unused land reduced by 6.8%. Landscape patch size was decreased, the degree of fragmentation and diversity of landscape was increased, and landscape structure in the study area became more complex. Moreover, vegetation coverage promoted from 2001 to 2013; average Fvc in 2013 was 1.5 times greater than that in 2001. The results can provide not only an accurate assessment for the EWDP, but also a visual insight for the water resources management practices in the study area, such that the sustainability for local ecosystem can be facilitated.     

滇西北高原闭合半闭合退化湿地的生态恢复效果

选取滇西北高原典型退化湿地纳帕海,对比植被恢复前后入湖河流廊道、草甸(汇水过渡区)、湖滨带植物群落物种的组成、水质、土壤有机质和全氮含量的变化,分析流域完整尺度恢复实践的有效性.结果表明:研究区湿地植物在恢复初期由8科12属13种迅速增加至18科22属28种;地上生物量从318.56 g·m-2上升到507.68 g·m-2;湖滨及河流岸带植物群落恢复前后变化明显,耐污种逐渐减少或消失,出现了消失多年的沼泽植物黑三棱和水毛莨群落;土壤有机质和全氮含量分别由恢复前的28.85和0.79g·kg-1增加到50.26和1.45g·kg-1,水体中的TN、TP和COD含量较恢复前显著下降,去除率分别达到67.9％、79.2％和71.2％,水体透明度提高了179％,湿地生态系统结构和功能得到了改善和恢复.在高原闭合半闭合湿地区,采取植被恢复措施及其技术方法行之有效.