Individual and demographic responses of a marsh bird assemblage to habitat loss and subsequent restoration

Background: The alteration and loss of habitats are two of the main threats that biodiversity conservation is cur?rently facing up to. The present study describes the effects of a perturbation and restoration in a reedbed habitat on a bird assemblage. We studied the bird community of a wetland of central Spain between 1995 and 2009, during which time an anthropic perturbation altered the original structure of the habitat;subsequently, as a result of restoration works, the habitat returned to its original state.Methods: We evaluated the effects on six population and physical parameters of the birds at three different phases of their life cycles(breeding, wintering and post?breeding migration seasons) before, during and after the habitat alteration. GLM was used to analyze the influence of three independent variables(year, perturbation phase and temperature).Results: The relative abundance and the species richness values decreased when habitat was altered, but then recovered as a result of the regeneration works. This pattern was the clearest amongst specialist species. Breeding success also declined during the perturbation phase and then increased;likewise, the sex ratio changed given that the proportion of male birds increased when habitat was altered. These results are discussed in relation to changes on availability of resources in altered habitats, to the adaptive mechanisms in the exploitation of ecological requirements and to the selection of optimum and sub?optimum habitats by generalist and specialist species.Conclusions: Ecosystem restoration can favour the recovery of population indexes of specialist passerines, although it depends on the efficiency of the type of restoration activity performed and on the complexity of the habitat.

Deforestation and Habitat Loss: Human Causes, Consequences and Possible Solutions

Deforestation leads to habitat loss while preservation and conservation of the natural forest increase biological diversity.Multiple factors have been reported to be responsible for deforestation and habitat loss,which could either be of human or natural origin.Natural causes of deforestation could be as a result of forest fires,droughts,exotic animals,floods,overpopula­tion of foreign animals and climate change.That notwithstanding,human activities are among the principal causes of global deforestation and habitat loss with agricultural expansion,cattle breeding,timber extraction,mining,oil extraction,dam construction and infrastructure development as some examples of these human influences.This study identifies agricultural ac­tivities and urbanization as the chief causes of human induced deforestation and habitat loss on a large scale.The simple and more practicable approach to curb the already alarming effects of deforestation and habitat loss is through environmental education of everyone still surviving on our planet.Environmental education is the key to reversing continuous and deliberate human actions through the protection of every natural forest and afforesta­tion where necessary.

Habitat Loss,Uneven Distribution of Resources and Fragmented Landscapes—A Resource Based Model of the Patch Size Effect

The problem of habitat fragmentation is recently an important issue in ecological research as well as in the practical approach of nature conservation. According to the most popular approaches, habitats are considered as the homogenous parts of the landscape. Also the metapopulation concept problem of the inert habitat heterogenity is considered quite seldom. These approaches have some weak points resulting from the assumption that the border between habitat patches and the metapopulation matrix is fairly sharp. This paper presents a resource-based concept of habitats, based on mathematical theory of point processes, which can be easily applied to analysing the problem of uneven distribution of resources. The basic assumption is that the random distribution of resources may be mathematically described as the realisation of a certain point process. According to our method, it is possible to calculate the expected quantities of available resources as well as the minimum area of habitat that includes the expected abundance of the resource. This approach may be very useful to understand some crucial phenomena in landscape ecology, such as the patch size effect and its connection to habitat loss and fragmentation.

Climate-change habitat shifts for the vulnerable endemic oak species(Quercus arkansana Sarg.)

Quercus arkansana(Arkansas oak)is at risk of becoming endangered,as the total known population size is represented by a few isolated populations.The potential impact of climate change on this species in the near future is high,yet knowledge of its predicted effects is limited.Our study utilized the biomod2 R package to develop habi-tat suitability ensemble models based on bioclimatic and topographic environmental variables and the known loca-tions of current distribution of Q.arkansana.We predicted suitable habitats across three climate change scenarios(SSP1-2.6,SSP2-4.5,and SSP5-8.5)for 2050,2070,and 2090.Our findings reveal that the current suitable habitat for Q.arkansana is approximately 127,881 km^(2) across seven states(Texas,Arkansas,Alabama,Louisiana,Mississippi,Georgia,and Florida);approximately 9.5%is encompassed within state and federally managed protected areas.Our models predict that all current suitable habitats will disap-pear by 2050 due to climate change,resulting in a northward shift into new regions such as Tennessee and Kentucky.The large extent of suitable habitat outside protected areas sug-gests that a species-specific action plan incorporating pro-tected areas and other areas may be crucial for its conserva-tion.Moreover,protection of Q.arkansana habitat against climate change may require locally and regionally focused conservation policies,adaptive management strategies,and educational outreach among local people.

Using the Lonsdorf model for estimating habitat loss and fragmentation effects on pollination service

One of the most important issues related to landscape ecology and ecosystem services is finding the pattern of habitat patches that offers the highest pollination in agricultural landscapes.In this regard,two processes of habitat loss and fragmentation strongly affect the relationship between pollination and the pattern of habitat patches.In the present study,we aimed to examine the effects of habitat loss and fragmentation on pollination separately.For this purpose,first,we generated different simulated agricultural landscapes,including two habitats of forest and agriculture.Then,according to the Lonsdorf model,we estimated the potential of the simulated landscapes in providing pollination in different scenarios.Finally,using statistical models,we estimated the effects of habitat loss and fragmentation on pollination at the landscape and farm levels.Our results showed that the effects of habitat loss and fragmentation on pollination were completely different at the landscape and farm levels.At the landscape level,fragmentation negatively affected pollination,but at the farm level,the maximum pollination rate was observed in the landscapes with a high degree of fragmentation.Regarding the habitat loss effects,our results showed that pollination decreased linearly at the landscape level as habitat amount decreased,but at the farm level,it decreased exponentially.The present study considered the level of analysis(i.e.,landscape and farm levels)as a critical factor affecting pollination changes caused by fragmentation.We showed that using the Lonsdorf model could lead to confusing results for the landscape ecologists and alert farmers who want to reduce the adverse effects of fragmentation on their products by creating new forest patches.Therefore,agriculturalists and landscape ecologists should consider that the pollination rate at the landscape and farm levels is completely different according to the model and provide contradictory results about the process of habitat loss effects on pollination.

Biodiversity responses to insular fragmentation in Amazonia: Two decades of research in the Balbina Hydroelectric Reservoir

As hydropower development expands across lowland tropical forests,flooding and concomitant insular fragmentation have become important threats to biodiversity.Newly created insular landscapes serve as natural laboratories to investigate biodiversity responses to fragmentation.One of these most iconic landscapes is the Balbina Hydroelectric Reservoir in Brazilian Amazonia,occupying>400000 ha and comprising>3500 forest islands.Here,we synthesise the current knowledge on responses of a wide range of biological groups to insular fragmentation at Balbina.Sampling has largely concentrated on a set of 22 islands and three mainland sites.In total,39 studies were conducted over nearly two decades,covering 17 vertebrate,invertebrate,and plant taxa.Although species responses varied according to taxonomic group,island area was consistently included and played a pivotal role in 66.7%of all studies examining patterns of species diversity.Species persistence was further affected by species traits,mostly related to species capacity to use/traverse the aquatic matrix or tolerate habitat degradation,as noted for species of vertebrates and orchid bees.Further research is needed to improve our understanding of such effects on wider ecosystem functioning.Environmental Impact Assessments must account for changes in both the remaining habitat amount and configuration,and subsequent long-term species losses.

Environmental determinants of social wasp diversity and assemblage structure in an Amazonian archipelagic landscape

Hydropower development has become an important driver of habitat loss and fragmentation across lowland tropical forests.Despite ample evidence on the detrimental effects of insular habitat fragmentation on biodiversity,invertebrate taxa,that may be critical to ecosystem functioning,have been overlooked.We assessed the assemblage-level responses of social wasps to forest insularization induced by the Balbina Hydroelectric Dam in Central Brazilian Amazonia.Employing Malaise trapping,we captured wasps on 27 forest islands and three continuous forests.We constructed Generalized Linear Models and employed a model selection approach to examine the impact of local variables(fire severity(FIRE)and basal area of pioneer tree species(PIONEER))and landscape-scale variables(amount of habitat(COVER))on patterns of species richness,composition,and body size of wasps.A total of 374 individuals(29 species)were collected across all sampling sites.COVER was the main predictor of species richness,while PIONEER was the only variable that explained variation in community composition,with a negative effect on body size.Our results add evidence to the pervasive impacts of large hydroelectric dams on tropical forest biodiversity,and suggest that social wasps,among other invertebrates,can be used as bioindicators in infrastructure development projects.

Post-fire habitat restoration of sables during winter season in northern slope of the Great Xing＇an Mountains

Habitat loss and fragmentation have been associated with the decline of endangered species. In 1987, a catastrophic fire in the northern Great Hing＇an Mountains of China, where the main habitat of sables （Martes zibellina） is located, aggravated the loss and fragmentation of the forest landscape. Due to restricted distribution and low population density, sables were listed in the national first-grade protected species in China. The objective of this paper was to identify to what extent the habitat of sables had been restored 13 years after the fire. Based on the behavioral data, which came from field survey information by radio-tracking, GPS （Global Positioning System） and forest inventory data, suitability habitat maps were derived using the Ecological Niche Suitability Model （ENSM）. In addition, the habitat structure was analyzed with selected landscape indices. Although forest cover mostly had been restored by 2000, the results indicated that, compared to the pre-fire situation, the areas of suitable habitat had been reduced significantly, especially those of less suitable, marginally suitable and moderately suitable designation. Fragmentation was aggravated, and suitable patches were found to be further isolated with the exception of those in most suitable areas. The ratio of the patch perimeter to area in unsuitable, moderately suitable and suitable areas decreased, while the ratios within other suitability types increased. Moreover, the percentage of soft boundaries decreased slightly, which can influence the redistribution of sables. The results above indicated that the suitable habitat had deteriorated, and the restoration of the sables＇ habitat remained to be done.

Habitat suitability change of red-crowned crane in Yellow River Delta Nature Reserve

Habitat loss and fragmentation are mainly associated with population decrease of endangered species and biodiversity loss. The habitat suitability maps of red-crowned crane （Grusjaponensis） in 1992, 1999 and 2006 were produced by using Ecological Niche Suitability Model （ENSM） in Yellow River Delta Nature Reserve （118°33′-119°20′E longitude, 37°35′-38°12′N latitude）, Shandong Province, China. Based on the habitat suitability maps, the causation and change law of habitat loss and fragmentation of red-crowned crane were analyzed by selecting a series of landscape pattern indices. Results showed that due to scarcities of fresh water sources, habitat suitability of red-crowned crane in 1999 was inferior to that in 1992 and 2006 no matter whether human disturbances existed or not. Besides, human disturbance activities, especially road disturbances, increased rapidly during the period of 1992-2006. This worsened the habitat loss and frag- mentation of red-crowned crane, and led to degrading habitat suitability of red-crowned crane in 2006, compared with that in 1992. In conclusion, fresh water sources and human disturbance activities are the two main factors that drive the habitat suitability change of red-crowned crane.

绿头鸭野外杂交研究综述

本文根据整理野外观察记录和发表文献,对绿头鸭Anasplatyrhynchos和其他野生鸭类的杂交现象进行综述。绿头鸭由于人工引入到世界各地,与当地的土著种的杂交而造成的生态和遗传多样性保护问题值得关注。国内仅有少量公开发表的野外观察记录,并缺乏对绿头鸭野外杂交现象的系统研究。我国的基因测序研究大多用于不同野鸭对家鸭基因来源的贡献的探讨,而对野外鸭群的杂交趋势缺少监测。国外研究人员以野外鸭群为研究对象,对绿头鸭与斑嘴鸭Anaszonorhyncha在俄罗斯、东亚和北美的杂交现象、趋势和原因进行了讨论;还对北美、东亚、俄罗斯以及新西兰等地的绿头鸭和当地鸭群发生的杂交趋势进行了遗传多样性研究。这些研究表明:(1)种间杂交带来基因遗传变异的同时,更多造成了全球范围内遗传多样性减少和物种生殖努力的损失;(2)人为因素对生态环境的改变造成鸭群适宜栖息地减少而引起不同种群同域性增加,是野外杂交增加趋势的一个重要原因。因此,本文认为利用基因测序技术对野生鸭种遗传多样性展开鉴定,确认栖息地丧失对鸟类遗传多样性的影响,将是生物多样性保护与管理的重要内容与趋势之一;并提出绿头鸭野外杂交率可作为栖息地变化的一个重要指标,需引起生物多样性保护研究者和管理者的重视。

Bird Diversity and Threaten to Their Habitat in Sathurukondan Birding Site in Batticaloa, Sri Lanka

Sathurukondan situated within the urban area of Batticaloa and adjacent to Batticaloa lagoon. This area lies in the migrant route disperse from the entry points from Eastern and Andaman route. This area is locally notable for their bird diversity as well as being a major habitat in Batticaloa. Blooming of urbanization causing drastic reduction of the mangrove forest is the main threat to these birds diversity due to their habitat loss. Considering that, the objective of this study was to determine the taxonomic composition and abundance of water and wading bird in this area. Point transact method was used to count the birds, and the counting was taken monthly. A total of 8,893 records of 65 species representing 36 families were recorded from July 2015 to July 2016. Simpson＇s diversity index and Shannon index in this area are about 0.95 and 3.34, respectively, showing the high diversity of this area. Migrant birds, such as common sandpiper （Actitis hypoleucos L.）, marsh sandpiper （Tringa stagnatilis B.）, common greenshank （Tringa nebularia G.） and other important species, such as lesser adjutant （Leptoptilos javanicus H.）, spot-bill pelican （Pelecanus philippensis G.） and near threatened jungle owlet （Glaucidium radiatum T.） were noted. This area contributes notably to the local avian biodiversity and has the ecotourism potential. It conceals the need of the conservation of this area.

生境丧失模式对竞争系统入侵结果的影响

近年来,有关生境丧失和生物入侵对于物种多样性的影响研究大多数集中于单个影响因素,而生境丧失、生物入侵等因素也可能同时存在,并对物种共存产生耦合作用。以生物入侵后的3物种竞争系统为研究对象,探讨不同入侵方式下的物种续存条件,同时在入侵后引入生境丧失过程,阐明不同模式生境丧失对入侵结果的影响机制。采用空间显含的元胞自动机模型进行研究,充分考虑统计随机性、空间关联性,并对模拟结果进行详细分析。研究结果表明:当丧失过程倾向于人为因素引起的模式特征时,如有大片农田水塘、道路村庄分布的丧失模式,生境丧失将加剧外来物种的扩散入侵和竞争入侵;当丧失过程偏向于自然环境下的丧失特征时,比如随机丧失或梯度模式丧失,生境丧失对物种的扩散入侵和竞争入侵将起到抑制作用,从而在一定程度上缓解本地物种的入侵危害;最后,生境丧失对竞争扩散入侵结果的影响与扩散入侵、竞争入侵相反。该研究结果对生物入侵控制相关研究及政策实施具有一定的启发和理论指导作用。

Impact of marsh changes on breeding cranes in Sanjiang Plain,northeastern China

In order to measure the impact of changes in the marsh on breeding Red-crowned Cranes (Grus japonensis) and White-naped Cranes (G.vipio) in the Sanjiang Plain,we conducted a complete crane súrvey in each of the summers of 2007 and 2008,and obtained information on the changes in its marsh through interpretation of satellite images in 1986,1995,2000 and 2005.A comparison between the 1984 and 2008 census shows that:1) the number of Red-crowned Cranes remained stable at about 300 birds,while the number of White-naped Cranes increased markedly; 2) the estimates of nests of Red-crowned cranes are close to the numbers of 1984,while approximately 90％ of the nests of these two crane species were distributed over five national nature reserves (NNRs); 3) the two crane species became more concentrated in three regions,i.e.,the Fuyuan Delta,the middle reaches of the Naoli and Qixing rivers,and the Xingkai Lake wetlands,rather as formerly in six regions.The area of the marsh decreased by 45％ within the 20-year period from 1986 to 2005.The major loss of the marsh area was in the form of a conversion to paddy fields and dry land,which can be primarily attributed to direct human activity under various economic and policy drivers.The disappearance of cranes in the Dulu and Abuqin rivers was induced by large-scale agricultural development.The fragmentation into and isolation of small areas of the marsh became increasingly more serious,which resulted in unsuitable condtions for crane breeding in small patches of the marsh.The number of cranes declined from 1984-1995 but had recovered remarkably by 2008,which may be due to theestablishment of a system of nature reserves,in place since 2000.The land ownership of the reserve plays a key role in maintaining the integrity of the wetland ecosystem,especially in Sanjiang,Honghe,Naolihe and Qixinghe NNRs,which together accommodated approximately 80％ of the population of cranes.However,we did not discover any nests at all in the provincial and municipal reserves,which may be attributed to high human disturbances in these areas.In the end,we propose some recommendations on reserve management.

三峡大坝运行前后西洞庭湖鱼类群落结构特征变化

鱼类是湿地生态系统中重要的组成部分,鱼类的群落结构动态直接反映湿地生境及外部驱动力的变化.三峡大坝运行后,长江中游江湖水文情势发生了变化,西洞庭湖地处洞庭湖西部,是受此变化影响最为直接的区域之一.为监测西洞庭湖鱼类群落结构变化特征,分析其变化原因,于2002年9月-2003年8月和2012年7月-2014年1月,在西洞庭湖进行了两次鱼类群落调查.共鉴定到鱼类7目17科91种,其中鲤形目最多,为58种,占总种数的63.7%.两次调查结果显示,三峡大坝运行后西洞庭湖鱼类物种数由85种下降到66种,Shannon-Wiener多样性指数和Pielou均匀度指数分别由5.00和1.11下降为4.14和1.00,鱼类个体小型化趋势明显.两次调查物种数和个体数量最多的类群均为底层、定居性、杂食性鱼类,且其比例有增加的趋势,而肉食性鱼类、中上层鱼类、半洄游性鱼类和产粘性卵、沉性卵鱼类个体数量占比均有减小的趋势,其中中上层鱼类变化有显著性差异.三峡大坝运行后10年间,西洞庭湖鱼类多样性呈现下降趋势.研究表明,西洞庭湖鱼类生境丧失、捕捞胁迫,加剧了一些特定类群的生存压力,并反映于鱼类群落结构的变化.

汶川地震对都江堰地区大熊猫生境的影响

为了明确汶川地震破坏区的空间分布特征及其对大熊猫生境的影响,选择在都江堰地区采用遥感数据解译和GIS模型分析相结合的方法进行了此项研究。研究结果表明:汶川地震及其产生的滑坡、泥石流等次生灾害造成的植被破坏区面积为12862hm2,其中78.64%的破坏区位于龙溪虹口自然保护区内部。地震破坏区在空间上主要分布在海拔1400～2400m,坡度20～55°之间的山坡上。地震造成都江堰地区21.63%的大熊猫生境丧失,其中海拔2200～3000m之间的大熊猫生境丧失比例较大。大熊猫生境破碎化程度严重,震后的生境斑块数量是震前的7.7倍。龙溪虹口自然保护区的大熊猫生境丧失更为严重,其丧失比例为32.15%,而保护区外部的大熊猫生境丧失较轻,其丧失比例为9.83%。地震造成该地区大熊猫生境丧失严重,生境破碎化加剧,为了增加大熊猫可利用的生境,在震后恢复重建中应当避免在大熊猫生境中开展旅游。

Status,threats and conservation needs for the continental population of the Red-crowned Crane

The Red-crowned Crane (Grus japonensis) is a globally endangered species.Although this species has received much attention by scientists,conservationists and the general public,the continental population of the Red-crowned Crane continues to face serious threats which affect not only its population dynamics but also its breeding and wintering habitats.Habitat loss and deterioration are the main causes of the decline of its population.With the massive loss of habitats in all parts of its range - breeding,stopover and wintering grounds - the cranes have been forced into crops and farmlands where cranes are more vulnerable to human activities,such as poisoning the cranes and conflicts with farmers.From our review of studies done over 30 years,the eastern flyway subpopulation has been stable or slightly increasing and the western flyway subpopulation of the Red-crowned Crane has sharply declined in recent years.The wintering population for the western flyway has declined from over 1100 to less than 500 birds.Not only is the size of the population reduced to less than 50％,but most recently the decline has occurred with frightening speed,by 50-150 birds per winter.The current wintering range for the west flyway is only about 8％ of its extent in the 1980s.Urgent actions for habitat protection,law enforcement and education need to stop the declining trend for this species.

大兴安岭北坡火后紫貂冬季生境适宜性与景观格局的恢复

由自然和人为原因引起的生境丧失与生境破碎化已严重影响到野生动物的生存。大兴安岭北坡是国家一级保护动物紫貂(Martes zibellina)的主要分布区,1987年发生在这里的特大森林火灾造成了森林景观的严重破碎化,紫貂的生存面临极大的威胁。本文的研究目的是为了确定火灾13年后,紫貂冬季生境的恢复程度。首先根据紫貂对冬季生境的喜好,选取对其生存影响较大的生态因子,结合数字化林相图,利用地理信息系统软件ArcGIS编制火烧前后的生境适宜性类型图。然后选取相关的景观格局指标,对火烧前后的生境格局进行对比分析。结果显示,尽管火后采取了一系列的森林恢复措施,但紫貂冬季适宜生境仍有大幅度减少,特别是中等适宜生境类型减少最为明显。适宜生境破碎化加剧,隔离度增加。适宜生境斑块的形状趋于简单,软边界比重有所增加。以上结果表明,与火前相比,紫貂生境明显恶化,需要较长的时间恢复。

近50年陕西凤县林麝分布区的变迁

于2005年夏季和2006年春季,采用问卷调查结合野外实地验证,对陕西凤县林麝(Moschus berezovskii)的现时及历史分布进行了分析,并将所得分布信息叠加至数字化地图,绘制成林麝近50年的分布区变迁图。结果表明:历史上,凤县是秦巴山区林麝的主要分布区之一,从20世纪80年代初开始,该县林麝数量大幅下降,至今分布区已严重萎缩并破碎化,总分布面积减少至50年前的1/3;目前林麝分布区主要在相对偏远、人为干扰较少的乡与乡的交界和县的边缘地区,分布区被人类聚居地及主要公路所隔离。造成这种现状的主要原因是过度捕杀、森林减少及道路建设。

生境破碎化对动物种群存活的影响

生境破碎是生物多样性下降的主要原因之一。通常以岛屿生物地理学、异质种群生物学和景观生态学的理论来解释不同空间尺度中生境破碎化的生态学效应。生境破碎化引起面积效应、隔离效应和边缘效应。这些效应通过影响动物种群的绝灭阈值、分布和多度、种间关系以及生态系统过程 ,最终影响动物种群的存活。野外研究表明 ,破碎化对动物的影响 ,因物种、生境类型和地理区域不同而有所变化 ,因此 ,预测物种在破碎生境中的存活比较困难。研究热点集中于 :确定生境面积损失和生境斑块的空间格局对破碎景观中物种绝灭的相对影响 ,破碎景观中物种的适宜生境比例和绝灭阈值 ,异质种群动态以及生态系统的生态过程。随着 3S技术的发展 ,生境破碎化模型趋于复杂 ,而发展有效的模型和验证模型将成为一项富有挑战性的任务。

小三江平原湿地东方白鹳(Ciconia boyciana)生境丧失的生态后果

采用生境套娃方法反映水禽——东方白鹳生境需求的层级系统基础上,利用GIS技术建立定量化分析模型,深入探讨了小三江平原生境丧失对东方白鹳生境空间分布的影响。结果显示:与初始状态1954年相比,东方白鹳繁殖生境丧失了81.9%,平均斑块面积缩小了88%;同时,生境面积的丧失是伴随生境破碎化过程发生的。1983之后生境破碎化明显加剧,到2005年生境连通度显著降低,生境处于高度破碎化状态。研究表明,生境丧失对东方白鹳繁殖生境的影响不仅取决于关键生境要素的变化,生境空间异质性改变更为重要。