Biodiversity and fish farming intensification in French fishpond systems

Fishponds are artificial ecosystems in which biodiversity may be strongly affected by fish farming management. We studied biodiversity variation along a gradient of fish farming intensification within a 180-pond sample of a French region to establish whether biodiversity primarily depended on extensive management with the alternative hypothesis that some habitat characteristics could compensate for the effect of intensification. We compared the relationships of three biodiversity indicators (breeding birds, protected plants, macrophytes) to an index of intensification and to habitat characteristics likely to influence each indicator. In all selected indicators, species richness did not vary according to the composite intensification gradient. Protected plant richness was best explained by periodic drainage, which could thus benefit biodiversity in intensified fishponds provided that shallow littoral areas are still present. Bird richness was linked to macrophyte cover and probably to reed bed areas. Macrophyte richness and coverage were negatively influenced by low water transparency and high fish biomass which seemed likely to affect bird habitat above 350–400 kg/ha. Aquatic vegetation, which may reflect interactive effects of environmental factors and fish farming management, may then contribute to assessment of the ecological status of fishponds under the E.U. Water Framework Directive.     

Study on coastal wetland habitat quality evaluation in Quanzhou Bay, Fujian, China

Coastal wetland is located in the active interface between land and sea, which is one of the richest biodiversity habitats, while it is seriously disturbed and destroyed by anthropogenic activities in both terrestrial and marine parts. Habitat serves as the basis for organism survival, providing food, shelter, water, space and so on, and habitat degradation and loss caused by intense anthropogenic activities is widely considered as the main reason for biodiversity decline and loss. However, there is still limited study on the evaluating methods of coastal wetland habitats, especially for those in a large scale. In this study, methods for evaluating coastal wetland habitat quality, including selecting indicators, setting value assignment criteria and weights were discussed systematically, a method of coastal wetland habitat quality evaluation was established, and the habitat quality in Quanzhou Bay was also evaluated as a case study. The present study provided a new concept and method to assess quantitatively habitat status, indicate the ecological status and its change, and also reflect and predict indirectly the ecological impact of human activities.Referring to the habitat evaluation system (HES) developed by United States in the mid 1970s, the evaluation method was established by thorough analysis of the characteristics of coastal wetland. The habitat indicators were selected in terms of three habitat factors as follows: chemical factors, including dissolved oxygen (DO), phosphate in seawater, sulfide in sediment, and regional priority pollutants; physical factors, including landscape naturalness index and coastline artificialization index; biological factors, including invasive species risk and area ratio of invasive alien species. Weights were established by Analytic Hierarchy Process, combined with several-round expert evaluation. Evaluation criteria providing principles for value assignment of each indicator, were established referring to previous standards and related researches. The final result for assessing habitat quality was indicated and stated by the value of Habitat Quality Index (HQI), which is the weighted sum of each indicator. Habitat quality increased with the HQI value, with value ranging from 0 to 100.The established evaluating method was applied to assess the habitat quality of Quanzhou Bay, located in the southeast coastal zone of Fujian Province, with a total area of 136.4 km², which is an important bay in Fujian. Quanzhou Bay wetland is a typical coastal wetland with diverse wetland habitats, including mangrove, estuary, island, aquaculture ponds, salt pan, shallow sea, mud flat and so on. The Quanzhou Bay is now seriously suffering environmental problems, e.g. eutrophication due to great discharge of domestic, agricultural and industrial wastewater, rapid urbanization and reclamation resulting in decreased wetland area, and the invasion of alien species. The evaluation results showed that the habitat quality index value was 68.13, 57.99 and 51.23 in 1989, 2002 and 2008, respectively, indicating that the habitat degraded gradually. The five major factors that led to decline of HQI value were phosphate in seawater, lead in sediment, landscape naturalness index and coastline artificialization index and area ratio of invasive alien species. Therefore, in order to improve and maintain habitat quality, it is urgent to control pollution, large-scale reclamation and Spartina invasion in Quzhou Bay.     

Study on coastal wetland habitat quality evaluation in Quanzhou Bay, Fujian, China

Coastal wetland is located in the active interface between land and sea, which is one of the richest biodiversity habitats, while it is seriously disturbed and destroyed by anthropogenic activities in both terrestrial and marine parts. Habitat serves as the basis for organism survival, providing food, shelter, water, space and so on, and habitat degradation and loss caused by intense anthropogenic activities is widely considered as the main reason for biodiversity decline and loss. However, there is still limited study on the evaluating methods of coastal wetland habitats, especially for those in a large scale. In this study, methods for evaluating coastal wetland habitat quality, including selecting indicators, setting value assignment criteria and weights were discussed systematically, a method of coastal wetland habitat quality evaluation was established, and the habitat quality in Quanzhou Bay was also evaluated as a case study. The present study provided a new concept and method to assess quantitatively habitat status, indicate the ecological status and its change, and also reflect and predict indirectly the ecological impact of human activities.
Referring to the habitat evaluation system (HES) developed by United States in the mid 1970s, the evaluation method was established by thorough analysis of the characteristics of coastal wetland. The habitat indicators were selected in terms of three habitat factors as follows: chemical factors, including dissolved oxygen (DO), phosphate in seawater, sulfide in sediment, and regional priority pollutants; physical factors, including landscape naturalness index and coastline artificialization index; biological factors, including invasive species risk and area ratio of invasive alien species. Weights were established by Analytic Hierarchy Process, combined with several-round expert evaluation. Evaluation criteria providing principles for value assignment of each indicator, were established referring to previous standards and related researches. The final result for assessing habitat quality was indicated and stated by the value of Habitat Quality Index (HQI), which is the weighted sum of each indicator. Habitat quality increased with the HQI value, with value ranging from 0 to 100.
The established evaluating method was applied to assess the habitat quality of Quanzhou Bay, located in the southeast coastal zone of Fujian Province, with a total area of 136.4 km², which is an important bay in Fujian. Quanzhou Bay wetland is a typical coastal wetland with diverse wetland habitats, including mangrove, estuary, island, aquaculture ponds, salt pan, shallow sea, mud flat and so on. The Quanzhou Bay is now seriously suffering environmental problems, e.g. eutrophication due to great discharge of domestic, agricultural and industrial wastewater, rapid urbanization and reclamation resulting in decreased wetland area, and the invasion of alien species. The evaluation results showed that the habitat quality index value was 68.13, 57.99 and 51.23 in 1989, 2002 and 2008, respectively, indicating that the habitat degraded gradually. The five major factors that led to decline of HQI value were phosphate in seawater, lead in sediment, landscape naturalness index and coastline artificialization index and area ratio of invasive alien species. Therefore, in order to improve and maintain habitat quality, it is urgent to control pollution, large-scale reclamation and Spartina invasion in Quzhou Bay.     

Effects of seasonality,isolation and patch quality for habitat selection processes by mute swans Cygnus olor in a fishpond landscape

Foragers in patchy environments do not only select sites for single patch characteristics, but also have to consider the local environment of such patches. We studied habitat selection by mute swans Cygnus olor in a wide and heterogeneous fishpond region (the Dombes, eastern France). In this study, we considered fishpond isolation, resource quality within fishponds and breeding status of mute swans during both summer and winter. Mute swans did not select aquatic habitat randomly within the landscape. During summer, the population spread preferentially on medium to large fishponds, in subregions with numerous or closely related waterbodies, without generating a clumped distribution of birds. In addition to a positive effect of local fishpond number (2 km radius), breeding birds also responded positively to fishpond size. Non‐breeders selected fishponds mainly according to their size. Intraspecific territoriality did not appear to limit the presence of non‐breeders (i.e. moulting flocks), since both breeders and non‐breeders could coexist on the larger fishponds. During winter, mute swans used medium to large reflooded fishponds after summer drainage. The surrounding aquatic environment of fishponds played a minor role in determining flocking, compared to actual patch quality. Flocking occurred on large fishponds that had reflooded after having dried the summer before, whatever the agricultural cultivation practiced in the summer following drainage. The results suggest that geographical aspects should be taken into account when considering the potential impact of this expanding species within such ecosystems, and also in more general management policies dealing with aquatic habitats for waterbird populations.     

盐城自然保护区两种人工湿地模式评价

在用能值分析对盐城自然保护区两种人工湿地研究的基础上 ,对其可持续发展提出了建议。在缓冲区建立以获取经济效益为目的的鱼塘是必要的 ,它为自然保护事业的发展提供了足够的资金反馈 ;为了减轻由于湿地开发带来的珍禽的生境压力 ,在核心区的边缘必须建立以招鸟为目的的水禽湖。水禽湖对鱼塘的面积比须在 0 .1 9和 8.0 0之间。当比例是0 .1 9时 ,系统获得最大经济效益 2 .1 3× 1 0 3US＄ /a.hm2 ,当比例是 8.0 0时 ,系统获得最大生态效益 1 .1 8× 1 0 3US＄ /a.hm2当比例是 0 .3 1时 ,系统获得相等的生态和经济效益 ,其和是 3 .79× 1 0 2 US＄ /a.hm2 比例 0 .3 1是保护区较优的选择。在此模式运作几年后 ,鱼塘须被改成水禽湖 ,且被划入核心区进行严格管理 ,核心区被扩大。同时 ,建议在江苏省“海上苏东”发展计划对海涂湿地大力开发的同时 ,必须建立一定比例的适于珍禽栖息活动的人工湿地 ,扩大自然保护规模 ,以保护珍贵的生物多样性资源。     

Predicted Effect of Landscape Position on Wildlife Habitat Value of Conservation Reserve Enhancement Program Wetlands in a Tile‐drained Agricultural Region

Justification for investment in restored or constructed wetland projects are often based on presumed net increases in ecosystem services. However, quantitative assessment of performance metrics is often difficult and restricted to a single objective. More comprehensive performance assessments could help inform decision‐makers about trade‐offs in services provided by alternative restoration program design attributes. The primary goal of the Iowa Conservation Reserve Enhancement Program is to establish wetlands that efficiently remove nitrates from tile‐drained agricultural landscapes. A secondary objective is provision of wildlife habitat. We used existing wildlife habitat models to compare relative net change in potential wildlife habitat value for four alternative landscape positions of wetlands within the watershed. Predicted species richness and habitat value for birds, mammals, amphibians, and reptiles generally increased as the wetland position moved lower in the watershed. However, predicted average net increase between pre‐ and post‐project value was dependent on taxonomic group. The increased average wetland area and changes in surrounding upland habitat composition among landscape positions were responsible for these differences. Net change in predicted densities of several grassland bird species at the four landscape positions was variable and species‐dependent. Predicted waterfowl breeding activity was greater for lower drainage position wetlands. Although our models are simplistic and provide only a predictive index of potential habitat value, we believe such assessment exercises can provide a tool for coarse‐level comparisons of alternative proposed project attributes and a basis for constructing informed hypotheses in auxiliary empirical field studies.     

湿地公园鸟类栖息地营建研究——以北京琉璃河湿地公园为例

北京地区处于全球候鸟东亚-澳大利西亚的迁徙路线上,是候鸟重要的迁徙路线,近些年,随着人为活动的影响,该区生境破碎化问题愈发突出,直接威胁着本地鸟种和过境迁徙鸟类的生存。为达到保护鸟类多样性的目的,需开展相应的栖息地恢复工作。不同生态类群的鸟类对栖息地有着不同的要求,相同鸟种在不同空间、季节和生活期对栖息地的选择也有着不同的特点。因而,鸟类栖息地恢复应针对目标鸟种根据其繁殖特点、巢位空间分布、食性特点、活动空间特点等进行规划营造。以北京房山琉璃河湿地公园为例,针对项目所在区域的鸟类分布特征,确定目标恢复鸟种,结合项目区现场条件,围绕目标鸟种对于栖息地水系、植被等方面的需求,从岸线重塑、水深设计、植物配置、生态鸟岛等方面规划设计鸟类栖息地修复措施。     

多尺度结合的西安市浐灞河湿地水鸟生境保护规划

城市湿地及其物种多样性的保护是城市生态建设的重要内容.结合西安市浐灞河湿地,对城市湿地水鸟生境的保护规划问题进行了探讨.经调查,西安市浐灞河段共发现水鸟20种,分属8目12科,孕育了丰富的水鸟多样性资源.同时保留有本地湿地植物种类,生境类型多样,具有很高的保护价值.浐灞河湿地水鸟生境的保护规划应以景观生态学、保护生物学、复合种群等相关理论为指导,区域/景观-局地-群落多尺度结合,保护与开发结合进行规划,具体从以下方面着手:生境网络的构建;小生境的设计,滨水地带土地利用格局优化及生境水深的控制;生境植物群落的构建.     

环胶州湾湿地规划对局地气象环境影响的个例分析

基于青岛市2008年发布的城市总体规划(2006～2020),利用城市尺度边界层大气数值模式模拟不同湿地类型和不同湿地面积建设方案下,青岛环胶州湾地区大气温度、风速的变化特征,并对环胶州湾湿地变化潜在的风险进行了分析.数值分析表明,城市水体湿地的设置有利于城市气温的减小,缓解城市热岛效应和提高地面风速;湿地面积减小,会造成局部地区气温升高,风速下降.影响气温、风速变化的区域主要集中在湿地面积增加和减少区域附近.与水体湿地比较,沼泽湿地对城市气象环境的调节作用较弱.这些认识对环胶州湾地区城市规划应重点考虑的因素给予了技术支撑.     

渤海沿岸湿地生物多样性变化特征

全球气候变化和人类活动干扰的加强,对全球生物多样性造成了前所未有的干扰和破坏。近年来随着我国东部沿海的人口经济快速增长、资源需求进一步增大,生物多样性保护面临着巨大的挑战,进而影响地区经济和生态环境的可持续发展。在区域尺度上评估我国滨海湿地生态系统生物多样性空间格局及其变化特征,对于科学认识和合理保护滨海湿地生态系统生物多样性,和制定生态环境保护决策具有十分重要的意义。以渤海沿岸湿地生态系统生物多样性为研究对象,通过InVEST模型,和物种丰富度指数,评价了该地区生物多样性现状及其变化。结果表明:(1)渤海沿岸湿地生态系统主要以水库坑塘为主,其次为草本沼泽。在2000—2010年期间,渤海沿岸湿地生态系统总面积几乎不变,主要为草本沼泽和水库坑塘之间的转换。(2)湿地生物多样性较高的区域主要分布在辽东湾中部、渤海湾东南部和莱州湾西北部。由于城市化进展的加快,人类活动的干扰加强,近10年来,渤海沿岸湿地生境质量逐渐降低,生物多样性呈退化趋势。频繁的人类活动对该地区湿地生物多样性产生巨大的负面影响,应多建立自然保护区加以保护。(3)生物多样性变化热点区主要分布在渤海湾东南部和莱州湾西北部。冷点区域主要集中在渤海湾的中北部。在渤海湾东南部和莱州湾西北部的变化热点区内,生物多样性呈改善趋势,说明有效的生态系统转换和湿地保护区的建立,可以实现发展与保护共存,达到了双赢的效果。     

Diversity of waterbirds wintering in Douz wetlands (south Tunisia): factors affecting wetland occupancy and species richness

Understanding the environmental factors shaping wetland attractiveness for waterbirds is an important question in wetland ecology and for conservation purposes. However, detailed data from numerous North African wetlands, notably those situated in inland areas, are still lacking. Thus, the aim of this study was to identify the factors influencing wetland use by waterbirds wintering in one of such poorly known habitat systems, namely the Saharan wetland complex of Douz, in south-western Tunisia. Thirty-four waterbird species (20 wading birds and 14 waterfowl species) were found to winter in this area. Using discriminant function analyses, we found that wetland size was the unique variable discriminating between occupied and unoccupied sites for total waterbirds and wading birds, while waterfowl distribution was related to both wetland size and water depth. Wetland size also provided the strongest predictor of species richness of wading birds, waterfowl and total waterbirds. Overall, our findings highlight the importance of wetland size as a key factor determining the attractiveness of wetlands for waterbirds wintering in the Saharan wetland complex of Douz. The possible explanations of this wetland size effect are discussed.     

Exploring an efficient habitat index for predicting population and abundance of migratory birds in Poyang Lake Wetland,South China

Poyang Lake wetland is an important wintering habitat of migratory birds with a complexity of coupled nature and human systems. Reported studies suggested that habitat indices were mostly developed based on single-class factors and scale-dependent. Therefore the indices might not be sufficient and applicable to predict regional changes for population and abundance of migratory birds (PMB and AMB) in Poyang Lake wetland at watershed and basin scales. In order to explore an efficient habitat index for predicting PMB and AMB, an integrated and scale-independent habitat index was proposed by integration of landscape and environmental temperature variables at basin and watershed scales. The landscape index and environmental temperature index based on single-class dominant factors, were also evaluated by weighted additive method. Multi-source data, including multi-spatial and temporal remote sensing images and field survey data, was used in this study. Results indicated that the average 10-night temperature in July (TN-Jul.) had dominant influence on PMB and the environmental temperature index was a better predictor for predicting PMB; AMB was influenced by both landscape and temperature variables and the proposed integrated habitat index was better for prediction of AMB in Poyang Lake wetland. The proposed integrated habitat index is a supplement of the single-class habitat index, which provides a more scientific technique for the study of biodiversity.     

雷州半岛湿地水鸟区系组成及生态分布的初步研究

1998年10月至2000年6月,对雷州半岛湿地水鸟区系组成及生态分布进行了调查,结果表明,雷州半岛湿地水鸟56种,隶属7目9科,种类最多的是鹭类（Ardeidae)、鸭类（Antidae)和Xin鹬类（Charadriidae and Scolopacidae),共有41种,56种水鸟中,古北界成分35种,占绝对优势;东洋界、广布种分别只有13和8种。以冬候鸟为主,共有33种;留鸟、族鸟和夏候鸟分别占13、7和3种。冬候鸟主要是鸭类和Xin鹬种类,留鸟主要是鹭类,本地的鸥类（Laridae)几乎都是冬候鸟,受各种协定或法规保护的水鸟有38种。雷州半岛的水鸟主要人布在沿海滩涂湿地,共有49种,红树林是最重要的水鸟栖息地,分布在这里的水鸟有37种。     

河口三角洲湿地健康生态圈构建:理论与方法

河口三角洲湿地生态环境保护和区域开发的矛盾突出,对湿地生态圈健康和栖息地生态功能产生直接而强烈的影响.健康的河口三角洲湿地生态圈是由自然过程的连续性、生态系统的连通性、生境的异质性以及食物网的多样性等多种因素共同决定的.本文讨论了健康湿地生态圈构建的基础理论,综述了景观生态网络构建、水文连通性网络构建、食物网构建以及生境异质性栖息地营建的理论与方法.在区域和景观尺度上,以土地利用-生态系统完整性为主线,阐明了湿地破碎化对湿地生态功能的影响,特别强调景观完整性、水文连通性对湿地栖息地的影响;在生态系统和群落尺度上,以食物网-生态系统稳定性为主线,强调食物网多样性、生境异质性对湿地生物圈构建的支撑作用.基于景观完整性、水文连通性、生境异质性和食物网多样性构建健康湿地生态圈,可为湿地生态环境保护和建设提供科学依据和技术支撑.     

Relative importance of isolation, area and habitat heterogeneity for vascular plant species richness of temporary wetlands in east-German farmland

The purpose of this investigation was to explore the determinants of vascular plant species richness for temporary, isolated wetland habitats which are influenced by hydrologic gradients and characterized by variation in habitat area. The dependent variables total plant species richness and the number of obligate wetland species were analyzed consecutively. In regression analyses habitat area explained between 11 and 15% of the variation in the dependent variables. Habitat area was correlated with the heterogeneity of the hydroperiods between the upper and lower parts of the hydrologic gradients. In multivariate regression analyses, habitat heterogeneity accounted for 70-77% of the variation in the dependent variables, and habitat area did not have a significant impact. The results are most consistent with the habitat heterogeneity hypothesis. I therefore concluded that area is a surrogate variable for habitat heterogeneity which directly enhances vascular plant species diversity. There was no significant impact of isolation on species richness. The data suggest that the expanses of agricultural fields are not an effective barrier to the dispersal of the studied plant species. Only 10 of,52 wetland species were negatively influenced by isolation. This group of species did not differ from the other wetland species with respect to dispersal strategies and longevity of seed banks. However, the longevity of the seed banks was generally high, and there was a dominance of species whose propagules are transported with the soil clinging to the feet of birds. The results are discussed in the context of accurate dispersal strategies and remnant populations, which may counteract the effects of isolation.     

Repopulation and colonization by birds in the Agmon Wetland,Israel

Lake Hula and its surrounding wetland in northern Israel were drained in the late 1950s and the dried wetlands were transformed into a diverse agricultural region with a 0.3 km2 nature reserve. A portion of the extinct Hula wetland was re-flooded in April 1994 by constructing a small lake, Agmon, and 90 km of canals. The purposes of this study were (a) to document the re-population and colonization of the new Agmon wetland by birds after its flooding, (b) to evaluate bird species richness in this new wetland in comparison to that in a nearby mature Hula Nature Reserve, and, (c) to investigate if the species originally present in the Hula Valley before the drainage had been re-established. The new lake has succeeded in attracting a large variety of water birds to the newly formed habitats, especially ducks, egrets and herons, plovers, waders and snipes. The distribution of bird species among the different habitats was not random. The northern section of the lake, which is shallow and has an open shore, had the largest number of species during 1995 and 1996 and was preferred by plovers, waders and snipes. A large roosting and breeding colony of thousands of egrets and herons was formed in the dense cattails ( Typha domingensis) in the southern section of the lake. Unlike the nearby Hula Nature Reserve, the new wetland lacks a large seasonally flooded area and is less attractive for feeding and breeding plovers, waders and stilts. The new wetland also has very little muddy area without vegetation and attracts few of the species that regularly feed in this habitat in the reserve. The new wetland enlarges the area of only a few of the habitats found in the nearby reserve and therefore attracts fewer species than it might otherwise. Recommendations for management of the new wetland include increased diversity of habitats, restriction of human activities and optimization of conflicts that have arisen between the needs of the wetland and those of nearby agriculture.     

黄河首曲湿地退化过程中植物群落组分及物种多样性的变化

黄河首曲湿地是黄河下游生态安全的重要屏障.通过实地调查,采用空间序列代替时间序列的方法,研究了黄河首曲湿地自然退化过程中植物多样性的变化,并用对比分析的方法研究了人工排水对植物多样性的影响.结果表明:在黄河首曲湿地自然退化过程中,经沼泽、沼泽化草甸、高寒草甸到草原化草甸,优势种向中生和旱生种演替,丰富度指数和多样性指数逐渐增大,即草原化草甸>高寒草甸>沼泽化草甸>沼泽,而优势度指数却逐渐减小,均匀度指数先降低后增加,植物物种多样性总体上表现为增加的态势.人为排水后,毒杂草在群落中的比例增加,导致丰富度指数和多样性指数增加,均匀度指数和优势度指数略有降低,群落相似性系数逐渐降低,主要是由于人工排水后,生境相对中生化,部分植物在群落内的零星分布导致多样性指数和丰富度指数增加,而均匀度指数下降.人工排水虽然增加了群落内的植物多样性,但增加的植物多为毒杂草,从而使湿地向杂草型退化方向演替.     

Habitat suitability modelling of an invasive plant with advanced remote sensing data

Aim  Lepidium latifolium (Brassicaceae; perennial pepperweed) is a noxious Eurasian weed invading riparian and wetland areas of the western USA. Understanding which sites are most susceptible to invasion by L. latifolium will allow more efficient management of this weed. We assessed the ability of advanced remote sensing techniques to develop habitat suitability models for L. latifolium .
Location  San Francisco Bay/Sacramento-San Joaquin River Delta, California, USA.
Methods  Lepidium latifolium distribution was mapped with hyperspectral image data of Rush Ranch Open Space Preserve, providing presence/absence data to train and validate habitat models. A high-resolution light detection and ranging digital elevation model was used to derive predictor environmental variables (distance to channel, distance to upland, elevation, slope, aspect and convexity). Aggregate decision tree models were used to predict the potential distribution of this species.
Results  Lepidium latifolium infested two zones: near the marshland–upland margin and along channels within the marsh. Topographical data, which are typically strongly correlated with wetland species distributions, were relatively unimportant to L. latifolium occurrence, although relevant microtopography information, particularly relative elevation, was subsumed in the distance to channel variable. The map of potential L. latifolium distribution reveals that Rush Ranch contains considerable habitat that it is susceptible to continued invasion.
Main conclusions  Lepidium latifolium invades relatively less stressful sites along the inundation and salinity gradients. Advanced remote sensing datasets were shown to be sufficient for species distribution modelling. Remote sensing offers powerful tools that deserve wider use in ecological research and management.     

Surrogate species versus landscape metric: does presence of a raptor species explains diversity of multiple taxa more than patch area?

Prioritizing conservation areas is a central theme in conservation biology. The use of surrogate species and landscape metrics to identify areas with high conservation value is common. However, few studies have examined the relative efficacy of these two surrogates. In this study, we compared the efficacy of the presence/absence (PA) of a top predator (Eastern Marsh Harrier, Circus spilonotus) and wetland patch area on species richness, total abundance, and community composition of birds, plants, and small mammals, but species richness and community composition only for plants, in a fragmented wetland landscape. Although harrier PA was an effective indicator of the distribution of birds, it had no significant efficacy on the distributions of plants and small mammals. Patch area was more effective indicator of the distributions of plants and small mammals. These results suggest that surrogate species can be more effective indicators than landscape surrogates when there are ecological linkages between surrogate species and the focal taxa (e.g., similarity of habitat requirements between surrogate species and focal taxa or hetero-specific attraction). On the other hand, landscape surrogates would be useful when ecological knowledge about the relationships is limited.     

年内水热条件变化对冬候鸟数量时空分布特征的影响机制

环鄱阳湖湿地是东亚重要的冬候鸟栖息地,由于湿地内部分区接纳水源的不同,人为活动及地表类型的差异,使得该区冬候鸟数量的时空分布特征相对复杂。综合利用遥感数据、冬候鸟航空调查数据及气象观测数据,借助分区相关性统计分析方法,研究不同尺度环鄱阳湖湿地年内水热要素对冬候鸟数量时空分布特征的影响;通过水文要素之间的相关性分析以及地表温度的时空分布格局研究,探索水热要素之间的耦合关系,进而揭示鄱阳湖区年内水热条件变化对冬候鸟数量时空分布特征的影响机制。研究发现:12月份气温是影响鄱阳湖湿地冬候鸟数量时空分布特征的驱动因素;受分区农业及生态特征的影响,水文条件的年内变异成为影响鄱阳湖冬候鸟数量时空分布特征的决定因素。研究结果为环鄱阳湖湿地冬候鸟栖息地的保护提供决策依据。