生态保护区外斑块对景观连接度的影响评价

快速的城市化过程带来的生境斑块破碎化及损失会影响物种迁移、捕食等生态活动,对生物多样性构成威胁。然而,现有生态保护区可能无法覆盖其内生物的必要活动范围。生态保护区外的生境斑块对于维持生态过程也具有重要作用,因此识别生态保护区外的关键斑块并加以保护非常重要。以北京市延庆区为研究区,划分两种生境斑块,即核心生境斑块和潜在生境斑块,并基于图论构建生境网络。考虑地表覆盖类型、坡度、人类活动等因素构建生境阻力面。结合未来土地利用类型变化的模拟,研究城市化过程对区域生境网络和景观连接度的影响,选用CLUE-S模型模拟土地利用类型变化的格局。结合生境斑块特征和未来城市土地利用变化情况设计了3种未来生境变化情景。利用连接概率指数(PC)和网络连接度变化率(dI)评价不同生境变化情景下生态保护区外潜在生境斑块的景观连接度重要性,判断保护优先顺序,并分析景观格局变化对不同迁移能力物种的影响。结果表明：生态保护区外的全部潜在生境斑块对维持生境整体景观连接度有最大2.15%的影响,单个潜在生境斑块对维持景观连接度有最大0.28%的影响。此外,景观格局及其变化对不同迁移能力物种的影响差异显著,因此需针对保护物种和城市生境特征设计保护方案,研究区需要优先保护大中型斑块和位于关键位置的小型斑块。为了满足对生物多样性保护的需求,建议在区分生境斑块保护优先顺序时考虑生境斑块对景观连接度的贡献和城市化扩展过程的压力。研究为城市生物多样性保护和生境管理提供了方法参考。     

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.     

农业景观生物多样性与害虫生态控制

现代农业的一个重要特征就是人类对农田生态系统的干扰强度及频率不断增加,严重影响农业景观的结构及其生物多样性.农业景观结构的变化及其生物多样性的丧失,必然引起生态系统服务功能的弱化,不利于实施以保护自然天敌为主的害虫生态控制.农业的集约化经营导致自然生境破碎化,减少了农业景观的复杂性,使得作物和非作物变成一种相对离散化的生境类型和镶嵌的景观格局;破碎化的生境不仅会减少某些物种的丰度,还会影响物种之间的相互关系及生物群落的多样性和稳定性.非作物生境类型如林地、灌木篱墙、田块边缘区、休耕地和草地等,是一种比较稳定的异质化环境.非作物生境较少受到干扰,可以为寄生性和捕食性节肢动物提供适宜的越冬或避难场所以及替代猎物、花粉和花蜜等资源,因此,非作物生境有利于自然天敌的栖息和繁衍,也有利于它们迁入邻近的作物生境中对害虫起到调节和控制作用.景观的格局-过程-尺度影响农田生物群落物种丰富度、多度、多样性以及害虫与天敌之间的相互作用.从区域农业景观系统的角度出发,运用景观生态学的理论和方法来研究作物、害虫、天敌等组分在不同斑块之间的转移过程和变化规律,揭示害虫在较大尺度和具有异质性的空间范围内的灾变机理,可为利用农业景观生物多样性来保护农田自然天敌,实施害虫的区域性生态控制提供新的研究思路和手段.     

土地利用变化对生境网络的影响——以苏锡常地区白鹭为例

生境网络对于物种更具有生态意义。研究土地利用变化对生境网络的影响,对破碎景观中种群的扩散和迁徙至关重要。研究结果有助于区域生境网络的恢复和完善,从物种的角度而非景观结构的角度优化生态网络。以城市化快速发展、土地利用变化明显的苏锡常地区为研究区域,优势湿地鸟类白鹭为代表物种,构建物种生境斑块约束条件概念模型,提出按照物种生活习性特征划分、选择生境斑块的方法,并从斑块和网络结构两个视角分析了土地利用变化对生境网络的影响。结果表明:(1)2000—2010年研究区白鹭生境的适宜地类总面积虽有所增加,但主要由于大量新增线性人为干扰致使白鹭生境网络质量下降;(2)白鹭生境网络在研究区不是全区覆盖的回路,基本由宜兴—溧阳片、无锡滨湖片、苏州吴中片和苏州阳澄湖片4个小片网构成,其完整程度按照宜溧片、滨湖片、吴中片、阳澄湖片降次排列;至2010年,宜溧片破坏最为严重,滨湖片和吴中片次之,阳澄湖片受破坏程度相对最弱。总体上,白鹭生境境况在10年间恶化明显,土地利用变化朝着不利于白鹭持续生存的方向发展。     

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。     

道路网络理论在景观破碎化效应研究中的运用——以浙江省公路网络为例

随着道路的不断建设,道路网络对自然生态环境的影响效应日益显著,众多生态学家开始从道路网络与自然景观的空间位置入手,研究不同组织形式的道路网络对自然生态系统产生的不同影响,从而探讨生态最优化的道路网络组织模式.旨在研究浙江省的干线公路网络对自然生态环境造成的影响,从而探讨生态最优化的道路网络组织模式.总结了道路网路理论的最新研究进展,介绍了由R. T. T. Forman和J. A. G. Jaeger提出的两个道路网络影响模型;随后运用Forman教授的道路网络理论分析了浙江省干线公路网络对森林景观的破碎化影响,并运用公路影响阈值分析方法对破坏较为严重的森林景观斑块进行了更为深入的分析,结果表明:国道、省道网络侵占的森林面积较大,对森林生态服务功能的发挥有着较大的影响;高速公路网络则使得森林景观斑块严重降级和破碎,极大地影响着生物多样性的保护.若按照目前的公路规划,到2020年底,由国道、省道和高速公路共同形成的道路网络将对浙江省的森林景观系统造成严重破坏;最后,对浙江省公路网络的布局提出了5点调整建议.     

坝上地区不同海拔农田和恢复半自然生境下尺蛾多样性

为研究生境恢复及地形变化导致的景观异质性对退化景观中生物多样性的影响,于2006和2007年对河北坝上3个不同海拔村庄的农田生境与恢复中的禁牧草地或再造林等半自然生境的尺蛾群落采用灯诱法进行取样调查,比较不同生境的尺蛾多样性.结果表明： 两种生境类型间物种数和个体数存在显著差异、不同海拔村庄物种数也存在显著差异,但不同海拔村庄间个体数差异不显著,不同海拔村庄间以及各村庄内农田和半自然生境稀疏标准化物种数和Fisher α指数无显著差异;非度量多维标度法(NMDS)显示不同海拔的不同生境下尺蛾群落结构显著不同.地形变化导致的景观异质性对坝上地区尺蛾群落组成及多样性影响显著,而无论是恢复中的草地、再造林等半自然生境还是农田生境均是维持尺蛾多样性的重要生境.注重不同地形条件下农田生境和半自然生境景观镶嵌体的保护对维持尺蛾群落γ多样性具有重要意义,但生境恢复能否促进尺蛾群落多样性恢复尚需长期监测.     

卧龙自然保护区大熊猫生境破碎化研究

生境破碎化主要有两个方面,一是形态（景观结构）上的破碎化;二是生态功能上的破碎化,将景观连接度的概念引入卧龙自然保护区大熊猫的生境评价研究中,通过选择影响大熊猫生存的３种典型景观因子;地形高度,地形坡度和食物来源,从生态功能上研究３种景观因子由于空间组合的不匹配而形成的生境破碎化现状,在生物各景观因子重要性的基础上进行景观连接模糊相对赋值,并建立景观连接度评价模型,在地理信息系统支持下,研究了卧龙     

基于不同视角与方法的北京市密云区生境规划对比

由快速城市化导致的生境破碎化严重影响了生态系统的服务功能。因此,保护与规划城市生境尤为重要。然而目前科学的生境规划设计方法仍有待探索,因为生境的定义具有不同的视角与内涵。基于保护生物学与景观生态学理论,对比了物种视角与景观视角下的2种规划思路,并结合北京市密云区的生境规划,分析对比2种方法的规划结果。在物种方法中,首先选取承担多种生态作用的豹猫为目标物种,运用HSI模型并结合专家赋值法和层次分析法确定每个评价因子的权重,最后通过ArcGIS计算选取高适宜性源地并建立生态网络。景观方法则基于ArcGIS、Guidos、Conefor等软件平台,采用MSPA和景观连通性分析方法,选取重要核心区源地并建立景观生境网络。研究结果表明,2种方法的源地分布差异较大。因此生境规划不能盲目选择一种方法,需有机结合2种方法得到源地与廊道结果。根据地块承载的生境生态功能重要程度确定源地核心保护区,以实现最佳的生境规划和有效的生态系统服务。     

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。     

Road networks predict human influence on Amazonian bird communities

Road building can lead to significant deleterious impacts on biodiversity, varying from direct road-kill mortality and direct habitat loss associated with road construction, to more subtle indirect impacts from edge effects and fragmentation. However, little work has been done to evaluate the specific effects of road networks and biodiversity loss beyond the more generalized effects of habitat loss. Here, we compared forest bird species richness and composition in the municipalities of Santarém and Belterra in Pará state, eastern Brazilian Amazon, with a road network metric called ‘roadless volume (RV)’ at the scale of small hydrological catchments (averaging 3721 ha). We found a significant positive relationship between RV and both forest bird richness and the average number of unique species (species represented by a single record) recorded at each site. Forest bird community composition was also significantly affected by RV. Moreover, there was no significant correlation between RV and forest cover, suggesting that road networks may impact biodiversity independently of changes in forest cover. However, variance partitioning analysis indicated that RV has partially independent and therefore additive effects, suggesting that RV and forest cover are best used in a complementary manner to investigate changes in biodiversity. Road impacts on avian species richness and composition independent of habitat loss may result from road-dependent habitat disturbance and fragmentation effects that are not captured by total percentage habitat cover, such as selective logging, fire, hunting, traffic disturbance, edge effects and road-induced fragmentation.     

The effects of landscape fragmentation on pollination dynamics: absence of evidence not evidence of absence

Animal‐mediated pollination is essential for both ecosystem services and conservation of global biodiversity, but a growing body of work reveals that it is negatively affected by anthropogenic disturbance. Landscape‐scale disturbance results in two often inter‐related processes: (1) habitat loss, (2) disruptions of habitat configuration (i.e. fragmentation). Understanding the relative effects of such processes is critical in designing effective management strategies to limit pollination and pollinator decline. We reviewed existing published work from 1989 to 2009 and found that only six of 303 studies considering the influence of landscape context on pollination separated the effects of habitat loss from fragmentation. We provide a synthesis of the current landscape, behavioural, and pollination ecology literature in order to present preliminary multiple working hypotheses explaining how these two landscape processes might independently influence pollination dynamics. Landscape disturbance primarily influences three components of pollination interactions: pollinator density, movement, and plant demography. We argue that effects of habitat loss on each of these components are likely to differ substantially from the effects of fragmentation, which is likely to be more complex and may influence each pollination component in contrasting ways. The interdependency between plants and animals inherent to pollination systems also has the possibility to drive cumulative effects of fragmentation, initiating negative feedback loops between animals and the plants they pollinate. Alternatively, due to their asymmetrical structure, pollination networks may be relatively robust to fragmentation. Despite the potential importance of independent effects of habitat fragmentation, its effects on pollination remain largely untested. We postulate that variation across studies in the effects of ‘fragmentation’ owes much to artifacts of the sampling regimes adopted, particularly (1) incorrectly separating fragmentation from habitat loss, and (2) mis‐matches in spatial scale between landscapes studied and the ecological processes of interest. The field of landscape pollination ecology could be greatly advanced through the consideration and quantification of the matrix, landscape functional connectivity, and pollinator movement behaviour in response to these elements. Studies designed to disentangle the independent effects of habitat loss and fragmentation are essential for gaining insight into landscape‐mediated pollination declines, implementing effective conservation measures, and optimizing ecosystem services in complex landscapes.     

Independent effects of habitat loss,habitat fragmentation and structural connectivity on forest‐dependent birds

Aim Habitat loss and fragmentation are amongst the greatest threats to biodiversity world‐wide. However, there is still little evidence on the relative influence of these two distinct processes on biodiversity, and no study, to date, has investigated the independent contribution of structural connectivity in addition to habitat loss and fragmentation. The aim of this study is to evaluate the independent effects of habitat loss (the decrease in total amount of habitat), habitat fragmentation per se (habitat subdivision) and structural connectivity (in the form of hedgerow networks) on the distribution of seven resident forest‐dependent birds in central Italy. Location Central Italy. Methods We strategically selected 30 landscapes (each of 16 km² in size) with decreasing total amount of forest cover and with contrasting configuration of patches and contrasting lengths of hedgerow networks. Presence/absence of birds in each landscape unit was studied through point counts. Results The amount of forest cover in the landscape had the strongest relative influence on birds’ occupancy, whilst habitat subdivision played a negligible role. Structural connectivity and the geographic position of the landscape unit played a relatively important role for four species. Main conclusions Our study shows the importance of disentangling the contribution of different landscape properties in determining distribution patterns. Our results are consistent with the fact that halting habitat loss and carrying out habitat restoration should be conservation priorities, since habitat loss is the main factor affecting the distribution of the target species; implementation of structural connectivity through hedgerows, instead, should be evaluated with caution since its contribution is secondary to the predominant role of habitat loss.     

Hopes and challenges for giant panda conservation under climate change in the Qinling Mountains of China

One way that climate change will impact animal distributions is by altering habitat suitability and habitat fragmentation. Understanding the impacts of climate change on currently threatened species is of immediate importance because complex conservation planning will be required. Here, we mapped changes to the distribution, suitability, and fragmentation of giant panda habitat under climate change and quantified the direction and elevation of habitat shift and fragmentation patterns. These data were used to develop a series of new conservation strategies for the giant panda. Qinling Mountains, Shaanxi, China. Data from the most recent giant panda census, habitat factors, anthropogenic disturbance, climate variables, and climate predictions for the year 2050 (averaged across four general circulation models) were used to project giant panda habitat in Maxent. Differences in habitat patches were compared between now and 2050. While climate change will cause a 9.1% increase in suitable habitat and 9% reduction in subsuitable habitat by 2050, no significant net variation in the proportion of suitable and subsuitable habitat was found. However, a distinct climate change‐induced habitat shift of 11 km eastward by 2050 is predicted firstly. Climate change will reduce the fragmentation of suitable habitat at high elevations and exacerbate the fragmentation of subsuitable habitat below 1,900 m above sea level. Reduced fragmentation at higher elevations and worsening fragmentation at lower elevations have the potential to cause overcrowding of giant pandas at higher altitudes, further exacerbating habitat shortage in the central Qinling Mountains. The habitat shift to the east due to climate change may provide new areas for giant pandas but poses severe challenges for future conservation.     

栖息地破碎化与鸟类生存

栖息地破碎化给野生动物带来的不良后果是全球生态学家和保护生物学家共同关心的问题.自从提出栖息地破碎化是导致生物多样性丧失的关键因素之一的论点后,近20年来,栖息地破碎化研究一直是生态学和保护生物学最活跃的前沿研究领域之一.栖息地破碎化是一动态过程,可在多尺度上发生并蕴涵着复杂的空间模式变化.栖息地破碎化对鸟类的生态学效应主要体现在面积效应、隔离效应和边缘效应等.这些效应影响着鸟类的分布、基因交流、种群动态、扩散行为、种间关系和生活史特征等,最终影响着鸟类的生存.介绍和总结了栖息地破碎化过程、研究的理论依据及栖息地破碎化对鸟类生存产生的诸多影响.     

Confounding factors in the detection of species responses to habitat fragmentation

Habitat loss has pervasive and disruptive impacts on biodiversity in habitat remnants. The magnitude of the ecological impacts of habitat loss can be exacerbated by the spatial arrangement -- or fragmentation -- of remaining habitat. Fragmentation per se is a landscape-level phenomenon in which species that survive in habitat remnants are confronted with a modified environment of reduced area, increased isolation and novel ecological boundaries. The implications of this for individual organisms are many and varied, because species with differing life history strategies are differentially affected by habitat fragmentation. Here, we review the extensive literature on species responses to habitat fragmentation, and detail the numerous ways in which confounding factors have either masked the detection, or prevented the manifestation, of predicted fragmentation effects.Large numbers of empirical studies continue to document changes in species richness with decreasing habitat area, with positive, negative and no relationships regularly reported. The debate surrounding such widely contrasting results is beginning to be resolved by findings that the expected positive species-area relationship can be masked by matrix-derived spatial subsidies of resources to fragment-dwelling species and by the invasion of matrix-dwelling species into habitat edges. Significant advances have been made recently in our understanding of how species interactions are altered at habitat edges as a result of these changes. Interestingly, changes in biotic and abiotic parameters at edges also make ecological processes more variable than in habitat interiors. Individuals are more likely to encounter habitat edges in fragments with convoluted shapes, leading to increased turnover and variability in population size than in fragments that are compact in shape. Habitat isolation in both space and time disrupts species distribution patterns, with consequent effects on metapopulation dynamics and the genetic structure of fragment-dwelling populations. Again, the matrix habitat is a strong determinant of fragmentation effects within remnants because of its role in regulating dispersal and dispersal-related mortality, the provision of spatial subsidies and the potential mediation of edge-related microclimatic gradients.We show that confounding factors can mask many fragmentation effects. For instance, there are multiple ways in which species traits like trophic level, dispersal ability and degree of habitat specialisation influence species-level responses. The temporal scale of investigation may have a strong influence on the results of a study, with short-term crowding effects eventually giving way to long-term extinction debts. Moreover, many fragmentation effects like changes in genetic, morphological or behavioural traits of species require time to appear. By contrast, synergistic interactions of fragmentation with climate change, human-altered disturbance regimes, species interactions and other drivers of population decline may magnify the impacts of fragmentation. To conclude, we emphasise that anthropogenic fragmentation is a recent phenomenon in evolutionary time and suggest that the final, long-term impacts of habitat fragmentation may not yet have shown themselves.     

Species richness and food web structure of soil decomposer community as affected by the size of habitat fragment and habitat corridors

While most ecologists agree that the effects of fragmentation on diversity of organisms are predominantly negative and that the scale of fragmentation defines their severity, the role of habitat corridors in mitigating those effects still remains controversial. This ambiguousness rests largely on various difficulties in experimentation, a problem partially solved in the present paper by the use of easily manipulated soil communities. In this 2.5‐year‐long field experiment, we investigated the responses of soil decomposer organisms (from microbes to mesofaunal predators) to habitat fragment size, in the presence or absence of habitat corridors connecting the fragments. The habitat fragments and corridors, composed of forest humus soil, were embedded in mineral soil representing an uninhabitable (or nonpreferred) matrix for the decomposer organisms. The results demonstrate that soil decomposer organisms do respond to changes in their habitat size: the species richness of microarthropods (mites and collembolans) increased as the size of the fragments increased. Especially collembolan species and predatory mites proved to be sensitive to the restricted habitat size, which is suggested to be a consequence of the large proportion of rare species and small and fluctuating population sizes in these groups. Contrary to our expectations, the presence of corridors had no positive effects on species richness or abundance of any of the studied faunas, possibly because of the low quality of the corridors. On the other hand, the biomass of soil fungi increased in the presence of corridors, which apparently provided a preferred pathway for vegetative dispersal of the fungi. Our results indicate that despite their characteristic underground environment, the response of soil decomposer organisms – in particular that of microarthropods – to habitat size is not unlike to that of the larger organisms in aboveground habitats.     

Habitat loss and connectivity of reserve networks in probability approaches to reserve design

Quantitative methods for the design of reserve networks often select over‐dispersed reserves, and consequently a number of species extinctions can be expected in such reserves, especially if unprotected surrounding habitat is lost. A novel approach that deals with this problem is presented by considering factors such as habitat quality and spatial configuration of reserves during the selection process. Species‐specific effects of habitat loss and fragmentation, together with habitat composition, are taken into account when computing species probabilities of local occurrence. Sites are then chosen to represent all species with a given target probability. The method is applied to a dataset of butterflies and moths from the Creuddyn Peninsula, North Wales, UK, which includes species with various responses to habitat quality and configuration. The results show that the resulting level of reserve clustering will depend on the number of species for which the spatial configuration plays an important role (at the scale under consideration), and on the pattern and amount of habitat loss that is expected to follow around the reserves. The method represents a step towards taking better into account species persistence when selecting reserve networks in a changing world.     

生境破碎化对植物-昆虫及昆虫之间相互关系的影响

生境破碎化对生物多样性和生态系统功能影响是当前国内外生态学家研究的热点问题之一。文章针对生境破碎化的内涵、量度指标进行介绍,着重分析生境破碎化对植物-昆虫关系的影响,包括植物与植食性昆虫的关系、植物与传粉昆虫的关系、种子与种子捕食者的关系,植物及其分解者的关系,还分析生境破碎化对昆虫-昆虫关系的影响,包括昆虫及其拟寄生物的关系、捕食者与猎物的关系。通过对上述方面的阐述,旨在更好地理解生境破碎化对动植物群落相互关系产生的深刻影响,并提出今后研究中应注意的问题和研究热点。