Enhance Landscape Connectivity Research Articles

Maximizing habitat connectivity in the mitigation hierarchy. A case study on three terrestrial mammals in an urban environment

Environmental policies and the objective of no net loss highlight the importance of preserving ecological networks to limit the fragmentation of natural habitats and biodiversity loss, especially due to urbanization. In the environmental impact assessment context, habitat connectivity and the spatio-temporal dynamics of biodiversity are crucial to obtaining reliable predictions that can support decision-making. We propose a methodological framework 1) to quantify the overall impact of a development project on the functioning of an ecological network, and 2) to select the best locations for implanting new habitat patches intended to enhance landscape connectivity. The amount of reachable habitat concept was applied to three representative terrestrial mammal species: the red squirrel, the Eurasian badger and the European hedgehog. All three species are recognized as vulnerable to human pressures and potentially affected by the construction of a new stadium in our study site, Lyon (Southern France). The method combines the species distribution model Maxent with the landscape functional connectivity model Graphab. The results showed that using any one of the avoidance and reduction measures on its own was unsuccessful in achieving the objective of no net loss when habitat connectivity is considered. However, the combination of new habitat patches and corridors offered a higher gain than distinct measures. This is especially important in the short term, when new hedgerow plantations have not yet developed enough to be used by the target species. Our findings indicate, first, the need to take the temporal scale into account in environmental impact assessment. We also show that applying the optimal scenario, constructed using a cumulative patch addition followed by a similar process testing a set of potential land-use changes, maximizes habitat connectivity. Our methodology provides a useful tool to increase target species’ habitat connectivity within the mitigation hierarchy and to enhance development project design for increased environmental efficiency.

Connectivity for species on the move: supporting climate‐driven range shifts

Many species are already responding to global climate change by shifting their ranges to track suitable climatic conditions. However, habitat loss and fragmentation, coupled with the rapidity of climate change, make it difficult for species to keep pace. It is therefore unsurprising that enhancing landscape connectivity is the most frequently cited climate‐adaptation strategy for conserving biodiversity. Yet most connectivity planning, even if intended to address climate change, does not directly take climate change and climate‐driven range shifts into account. Nonetheless, several approaches that do explicitly address the unique challenges posed by climate change have recently emerged. We review these connectivity modeling approaches: specifically, how they incorporate species' responses, identify movement routes, and address uncertainties. Despite this proliferation of approaches, conceptual and analytical hurdles remain, and meeting these challenges will be critical to achieving effective landscape connectivity for species in the face of climate change.

Recovery of floristic diversity, composition and structure of regrowth forests on fallow lands: implications for conservation and restoration of degraded forest lands in Laos

In Laos, there are extensive shifting cultivation areas and regrowth forests spontaneously established on fallow lands. The aims of the study were to conduct a comparative study of old-growth and regrowth forests in terms of structure, woody species diversity and composition as well as to investigate the potential role of regrowth forests in the conservation and restoration of degraded forest lands in Laos and the tropics in general. Systematic plot sampling was used to survey the floristic diversity, species composition and structure of old-growth and regrowth forests. Concentric circular plots with an area of 200 m2 and 500 m2 were laid on line transects. A total of 24 plots were sampled from two sites. In comparison to regrowth forests, old-growth forests had higher structural heterogeneity because of higher canopy height variations, vertical stratification, and tree sizes and their variations. Species richness and diversity indices values were similar, but abundance and species composition were significantly different between old-growth and regrowth forests. It appears that species richness recovers first followed by forest structure and species composition. Regrowth forests are important for in situ conservation of tropical biodiversity and they can also serve as a conduit for the restoration of degraded lands and forests. Regrowth forests provide habitats, serve as buffer zones around the fragmented old-growth forests, function as source of propagules, and enhance landscape connectivity. Utilization of regrowth forests for restoration purposes is comparatively inexpensive. Regrowth forests should be given the due considerations in the national forest conservation and restoration policy of Laos.

Identification of strategic corridors for restoring landscape connectivity: application to the Iberian lynx

AbstractThe conservation or creation of ecological corridors is a key to support species persistence in fragmented landscapes. However, little guidance exists on where to concentrate the restoration measures to improve corridor quality and functionality. Focusing on the emblematic Iberian lynx Lynx pardinus as the target species, and using a resistance surface parameterized through detailed telemetry data for the species, we applied a modeling approach that identifies corridors whose restoration would be more beneficial for enhancing landscape connectivity. Connectivity benefits were quantified, first, as the increase in the Probability of Connectivity metric (dPC) that results for the entire population network after reducing the effective distance along a particular corridor to its minimum possible value through restoration, and second, as dPC normalized by a proxy of the total restoration effort that would be required in each corridor. Results showed that the corridor restoration benefits were related to their effective distance (accumulated cost of movement along the corridor) and network centrality (potential frequency of use by dispersing individuals) in the current landscapes. Two corridors in which restoration efforts may be more desirable for the Iberian lynx were highlighted: the one linking the Doñana‐Aljarafe population with other populations and reintroduction areas further north, and a west‐east axis connecting the different populations in Sierra Morena. In general, the applied approach is a valuable tool to estimate how landscape connectivity may be affected when changes in the landscape are planned or can be predicted. This approach can be applied to potential corridors linking future reintroduction areas of the Iberian lynx, to case studies focusing on other landscapes and animal species, or to evaluate the impacts of corridor degradation or loss due to land use changes and other pressures.

Enhancing landscape connectivity through multifunctional green infrastructure corridor modeling and design

Landscape connectivity is critical for ecosystem health and biodiversity conservation, yet urbanization is increasing habitat fragmentation. Green corridors that connect isolated remnant habitat patches (e.g. parks) can increase connectivity and provide ecosystem services in cities. Vacant land, especially prevalent in shrinking cities, presents a unique opportunity to reconnect these landscapes. This paper provides a practical and replicable approach for assessing landscape connectivity patterns and identifying priority locations for green corridors. The methodology integrates social and ecological factors coupled with site-scale multifunctional greenway designs and is applied to the city of Detroit as a proof of concept. First, we use FRAGSTATS to evaluate structural landscape connectivity patterns at a census tract scale. A functional connectivity assessment based on graph theory and Conefor software is used to validate the results, which indicate that habitat is highly fragmented in Detroit. To identify opportunities to reduce this fragmentation, we use a least-cost path approach to map potential green corridors linking city parks through vacant parcels, alleys, and smaller green spaces, and prioritize these corridors using a gravity model and network analysis. To make the model more concrete and useful for decision-makers, we develop site-level multifunctional corridor design typologies. This study presents a novel approach to assessing urban connectivity and a multi-scalar, systematic methodology for planning urban green infrastructure networks that connects landscape ecology with practical planning and design considerations to maximize social and ecological functions.

A Study of the Relationship between Ecological Network Patch metrics and Landscape connectivity; with reference to case of Colombo Wetlands

Landscape fragmentation and habitat loss are emergent issues in Sri Lanka, which is a result of rapid urban development and inadequate concern of managing Landscape connectivity. Inland Wetlands and forests are the most valuable ecosystems effected from the fragmentation. Considering those habitats, Wetlands are among the most productive, active, diverse, and beneficial ecosystems in nature threatened by the urbanization. Therefore, this study aimed to introduce spatial strategies to locate landscape developments to restore landscape connectivity; referring to Colombo wetlands. Though the fragmentation causes alteration of wetland structure, fragments does serves to landscape connectivity functioning as an ecological network. Therefore the study aims to understand how the habitat/ ecological network patch metrics contribute to landscape connectivity. Two main methods used; to calculate the patch metrics; Patch area, Total edge, Perimeter-area ratio, Core area index and Inter-patch distances; GIS data have been used. Further, GIS enables least-cost path tool to be used to measure the Landscape connectivity and calculate number of species flow paths per wetland patch. With the data analysis, the study investigated the relationship between the patch metrics and the landscape connectivity. Referring to the findings, the study discussed; increasing the patch area, maintaining a mean perimeter-area ratio or core area index, reducing the inter patch distances could enhance landscape connectivity within in the urban wetland habitat patches. At the end, the study introduces strategies for Landscape architects to select most suitable locations to implement ecological based landscape developments adjacent to the existing urban habitat in order to enhance patch metrics and to restore the landscape connectivity Keywords: Landscape fragmentation, Ecological networks, Patch metrics, Landscape connectivity

How Legal-Oriented Restoration Programs Enhance Landscape Connectivity? Insights From the Brazilian Atlantic Forest

Environmental legislation has fostered ecological restoration programs worldwide, but few studies have reported the outcomes for landscape connectivity. Here, we investigated the contribution of forest restoration programs planned to comply with the Brazilian Forest Code for increasing forest cover and landscape connectivity in agricultural landscapes of southeastern Brazil. We gathered data for 85 landscapes and 2,408 rural properties, totalizing 748,601 ha of farmlands within the Atlantic Forest biome and its ecotone with Cerrado, two global hotspots for biodiversity conservation. Together, rural properties account for 50,783 ha of native vegetation deficit found on Areas of Permanent Protection (APPs). On the basis of this, we performed a landscape connectivity analysis by simulating scenarios in accordance with the requirements of the legislation for two sugarcane mills that are already under ongoing restoration efforts. We evaluated the relative changes promoted by restoring all deforested riparian buffers within APPs, as determined by the Forest Code. The simulation of restoration at the property-level resulted in the reconnection of isolated forest patches, reducing their number in the landscape and increasing their overall and core size. At the sugarcane mill level, the restoration of riparian forests increased the index of connectivity. Despite these benefits, final forest cover (remnant plus restored forests) would still be reduced (<20%—the minimum forest cover on the private land to comply with the environmental law) in most landscapes and insufficient to conserve species sensitive to forest fragmentation. The mandatory restoration of riparian buffers plays a relevant role for improving landscape connectivity in human-modified tropical landscapes, but this strategy shall be complemented by other approaches to increase forest cover and landscape connectivity to mitigate the enormous species extinction debt accumulated for tropical forests.

林地面积比例梯度下景观组成和构型对生物多样性的影响

PDF HTML阅读 XML下载 导出引用 引用提醒 林地面积比例梯度下景观组成和构型对生物多样性的影响 DOI: 10.5846/stxb201410011945 作者: 作者单位: 河南大学,河南大学,河南大学,河南大学 作者简介: 通讯作者: 中图分类号: 基金项目: 国家自然科学基金资助项目(41471146,41071118);河南省高校青年骨干教师资助计划项目(2012GGJS-031) Effects of woodland composition and configuration along a woodland area ratio gradient on biodiversity conservation Author: Affiliation: College of Environment and Planning，Henan University，Kaifeng,College of Environment and Planning，Henan University，Kaifeng,College of Environment and Planning，Henan University，Kaifeng,College of Environment and Planning，Henan University，Kaifeng Fund Project: 摘要 | 图/表 | 访问统计 | 参考文献 | 相似文献 | 引证文献 | 资源附件 | 文章评论 摘要:以黄河中下游郑州地区为研究区域,根据林地面积比例高低,把确定的260块景观区域划分为林地面积比例高(>50%)、中等(50%-30%)、低(30%-10%)和非常低(<10%)共4个不同类型;采用概率连接度指数(PC)表征林地栖息地可用性程度。利用R软件里的广义线性模型(GLM),分析了10、50、100、250、500、1000、2000 m和3000 m物种不同扩散能力下,反映林地景观组成和构型特征的林地面积比例(PA),以及林地面积比例(PA)与林地斑块数量(NP)、林地平均斑块大小(PS)、林地斑块隔离度(PI)组合作用对栖息地可用性的影响。结果表明:在林地面积比例高的区域,林地面积比例是决定栖息地可用性程度的重要影响因素;在林地面积比例中等的区域,除林地面积比例外,林地斑块隔离度和平均斑块大小是主要影响因素;在林地面积比例低和较低时,依据物种扩散能力的不同,需要考虑平均斑块大小和林地斑块数量的影响。景观中不同林地面积比例情况下,生物保护措施和管理要依据林地面积比例、林地斑块数量、林地平均斑块大小、以及林地斑块隔离度。 Abstract:Biodiversity is one of the key factors affecting ecosystem services, and there are very close connections between agricultural ecosystem and species diversity. The expansion of agricultural land and enhancement of land intensive utilization cause great pressure on the protection of agricultural landscape biodiversity. In highly intensive agriculture landscape, woodlands are important habitats for biodiversity protection. Reduction of the vegetation coverage can lead to changes of habitat patch composition and configuration, which mainly including the decrease of mean patch size and increase of patch isolation degree and number of patches, then impacts species dispersal and settlement. Landscape heterogeneity can affect a variety of ecosystem processes, functions and ecosystem services. The composition and structure of biological habitats in agricultural landscape have an important role in maintaining species diversity. This also makes the transformation of biodiversity protection approaches from species centered to multifunctional landscape planning. Though the composition of landscape habitat patches is crucial for species survival, whether organisms can migrate successfully from one habitat patch to another or not also depends on the landscape connectivity between the two patches. The landscape connectivity level is determined by landscape structure and organisms' behavior characteristics together. To avoid species loss in landscape level, enhancing landscape connectivity becomes particularly important. The aim of this study is to investigate the contribution of the proportion of woodlands area (PA), number of patches (NP), mean patch size (PS), mean patch isolation (PI) for habitat availability (characterizing by probability index of connectivity, PC) along a gradient of woodlands area. Zhengzhou, Henan Province, a typical agricultural region in the middle and lower reaches of the Yellow River, was selected as the case study area. The mixed-effects models (Multi-model Inference, MMI) were applied to model the effects of woodlands landscape characteristics and habitat availability. The explanatory variables are landscape characteristics, namely PA, NP, PS, PI, and eight hypothetical species dispersal abilities (10、50、100、250、500、1000、2000 m and 3000 m). 260 landscapes units are classified into four scenarios according to the proportion of woodlands area, high ( > 50%), intermediate (50%-30%), low (30%-10%) and very low ( < 10%). The analytical results show that, in regions with high proportion of woodlands area ( > 50%), the proportion of woodlands area is the most important factor that affects the degree of habitat availability. In regions with intermediate proportion of woodlands area (50%-30%), besides the proportion of woodlands area, mean patch isolation and mean patch size are the main factors that must be considered. In regions with low and very low proportion of woodlands area ( < 30%), depending on the different species dispersal abilities, it is need to consider the effect of mean patch size and number of patches. For landscape management, we suggest that, conservation efforts should focus on maintaining the current forest, especially in landscapes with high proportion of woodlands area. While in landscapes with intermediate and low proportion of woodlands area, restoration should aim at enhancing habitat availability and reducing isolation. In the regions with very low proportion of woodlands area, managers must put the habitat restoration in the first place to avoid local extinction. 参考文献 相似文献 引证文献

Survival in patchy landscapes: the interplay between dispersal, habitat loss and fragmentation.

Habitat loss and fragmentation are important factors determining animal population dynamics and spatial distribution. Such landscape changes can lead to the deleterious impact of a significant drop in the number of species, caused by critically reduced survival rates for organisms. In order to obtain a deeper understanding of the threeway interplay between habitat loss, fragmentation and survival rates, we propose here a spatially explicit multi-scaled movement model of individuals that search for habitat. By considering basic ecological processes, such as predation, starvation (outside the habitat area), and competition, together with dispersal movement as a link among habitat areas, we show that a higher survival rate is achieved in instances with a lower number of patches of larger areas. Our results demonstrate how movement may counterbalance the effects of habitat loss and fragmentation in altered landscapes. In particular, they have important implications for conservation planning and ecosystem management, including the design of specific features of conservation areas in order to enhance landscape connectivity and population viability.

Woodland bird response to landscape connectivity in an agriculture-dominated landscape: a functional community approach

Over the last 30 years, ecological networks have been deployed to reduce global biodiversity loss by enhancing landscape connectivity. Bird species dwelling in woodland habitats that are embedded in agriculture-dominated landscapes are expected to be particularly sensitive to the loss of connectivity. This study aimed to determine the role of landscape connectivity in woodland bird species richness, abundance, and community similarity in north-east Brittany (north-west France). An exhaustive woodland selection protocol was carried out to minimize the effects of woodland size on the response variables. Connectivity of the woodland and forest network in the study area was evaluated using graph-theory, accounting for matrix permeability, and a characteristic median natal dispersal distance at the community level based on the bird species pool recorded in the sampled woodlands. Information-theoretic model selection, controlling for woodland size in all the cases, depicted the response of woodland birds at the community level to the connectivity of agriculture-dominated landscapes. On average, the sampled woodlands (n = 25) contained 15.5 ± 2.4 bird species, with an abundance of 25.1 ± 3.9, and had highly similar bird communities (species composition and proportion); eight species represented 57% of total abundance and were present in at least 22 woodlands. The performance of models improved when using effective, rather than Euclidean, interpatch distances in the connectivity assessment. Landscape connectivity was only significantly related to similarity of proportional species composition. Large woodlands contained communities with more similar species proportions in an inhospitable agricultural landscape matrix than in a more permeable one. Woodland size was the most relevant factor determining species abundance, indicating that the bird population sizes are primarily proportional to the local habitat availability. Connectivity in relation to landscape matrix permeability did not seem to induce the flow of woodland-dependent bird species that are dominant in the community but rather of matrix-dwelling bird species that are less dependent on woodland patch area. In conclusion, both habitat conservation and restoration (i.e., amount and quality), in combination with permeable landscape structures (such as heterogeneous land cover mosaics), are advocated for community level conservation strategies.

Landscape connectivity dynamics based on network analysis in the Xishuangbanna Nature Reserve, China

Lack of landscape connectivity and habitat loss is major threats to biodiversity and ecosystem integrity in nature reserves aimed at conservation. In this study, we used structural pattern and functional connectivity metrics to analyze the spatial patterns and landscape connectivity of habitat patches for the Shangyong sub-reserve of the Xishuangbanna Nature Reserve from 1970, 1990, and 2000. On the basis of vegetation and land cover data, we applied the equivalent connected area ECA(PC) indicator to analyze the changes in forest connectivity. Four distance thresholds (2, 4, 8, 12 km) were considered to compare the patch importance of connectivity by dECA values. The results showed the declining trends of landscape connectivity measured by ECA(PC) index from 1970 to 2000. The importance of connectivity in each forest patch varied with the increment of dispersal distances at the patch level, and some important habitat patches, which exhibit a potential to enhance landscape connectivity, should be given more attention. The least-cost pathways based on network structure were displayed under four dispersal distances in three periods. The results showed that the number of paths among the fragments of forest patches exhibited radical increases for larger dispersal distances. Further correlation analyses of AWF, ECA (IIC), and ECA (PC) showed the weakest and least-frequent correlations with the structural pattern indices, while H presented more significant correlations with the PD fragmentation metric. Furthermore, Kendall's rank correlations between the forest patch area and functional connectivity indicators showed that dECA (PC) and dAWF indicators should provided the area-based prioritization of habitat patches. Moreover, the low-rank correlations showed that dF and dLCP can be considered as effective and appropriate indicators for the evaluation of habitat features and network patterns.

Effectiveness of eucalypt plantations as a surrogate habitat for birds

In the fragmented forest landscape of Europe, tree plantations comprise an increasingly important fraction of the matrix surrounding natural forest fragments. Plantations may provide habitat for forest biodiversity, which may enhance landscape connectivity and regional biodiversity. I compared the diversity and composition of bird communities in eucalypt plantations of three ages (young, intermediate and mature) and with low management intensity with respect to pine plantations, native forests and shrublands. Differences in composition of species and species groups were analyzed with PERMANOVA and visually represented using NMDS ordinations. Species groups were established according to diet, habitat and microhabitat preferences, and conservation status. A total of 887 bird encounters and 45 species were recorded. Native forests had the highest species richness per site and per sample, followed by pine plantations and shrublands. Eucalypt plantations had the lowest species richness, and decreasing with age, and the lowest bird abundance. According to composition, two habitat groups could be distinguished: wooded habitats, including native forests and plantations except young eucalypt plantations; and shrubby habitats, with shrublands and young eucalypt plantations. Native forests and pine plantations had the most similar composition among wooded habitats, and were associated with forest specialists, whereas species having unfavorable conservation status were associated with shrublands and young eucalypt plantations. In eucalypt plantations, birds were mainly associated with shrubs at young ages and with canopies at older ages, with flowers as an important food resource. The paucity of birds in eucalypt plantations contrasted with the diverse and abundant avifauna in pine plantations. The alien status and taxonomic isolation of Eucalyptus globulus in the region, together with specific features of its leaves and bark, may explain the low suitability of eucalypt plantations, by limiting the presence of phytophagous insects and thus the availability of prey for birds.

Connectivity and invasive species management: towards an integrated landscape approach

Invasive plants and animals are a major cause of global biodiversity loss. Invasive Species Management (ISM) helps conserve localized populations and ecosystems, but rarely have its potential benefits been explored at the landscape scale. We explore how ISM can enhance landscape connectivity, and how its incorporation into conservation planning algorithms could help design optimal reserve networks. Conversely, conservation planning and connectivity modelling can optimize targeting of ISM, achieving benefits for a wider range of taxa and ecological processes, without the need for additional resources. Empirical research must investigate the spatial pattern of benefits from ISM, and when to target priority conservation sites or the areas (matrix) between them. By bolstering populations within—and increasing connectivity between—focal patches, ISM should move beyond conserving individual sites to creating functionally connected networks of conservation areas.

Landscape prerequisites for the survival of a modelled metapopulation and its neutral genetic diversity are affected by climate change

In response to climate change a species may move, adapt, or go extinct. For the adaptability of a population its genetic diversity is essential, but climate change-induced range shifts can cause a loss of genetic diversity. We investigated how landscape structure affects the level and distribution of genetic diversity in metapopulations subject to climate change-induced range shifts. For this we used the spatially explicit, individual-based model METAPHOR which simulates metapopulation demography and genetics under different temperature increase scenarios. The results indicated that increasing total habitat area may enhance the maintenance of the genetic diversity in metapopulations while they are shifting their range under climate change. However, the results also showed that a high level of total habitat area did not prevent the populations in the newly colonised habitat area of being depleted of much of the original genetic diversity. We therefore conclude that enhancing landscape connectivity may lead to a delayed loss of genetic diversity in metapopulations under climate change, but that additional measures would be necessary to ensure its long-term conservation. Importantly, our simulations also show that a landscape which could be regarded as well-structured under stable climatic conditions, may be inferior for the conservation of genetic diversity during a range shift. This is important information for landscape management when developing strategies for the in situ conservation of genetic variation in natural populations under climate change.

Reframing the debate over assisted colonization

Assisted colonization – also known as managed relocation or assisted migration – is one way of facilitating range shifts for species that are restricted in their ability to move in response to climate or other environmental changes. Over the past decade, a healthy debate has evolved in the scientific community over the costs and benefits of assisted colonization as a climate‐adaptation strategy. This discussion has focused largely on the specific risks and benefits of intentionally moving species, and has led to the development of multiple frameworks and numerous recommendations for weighing and evaluating these factors. Here, we argue that this debate is, in part, misguided, and that a more productive discussion would result if the issue were reframed in light of (1) the goals of assisted colonization, (2) the realities of projected climate impacts, and (3) the use of complementary adaptation strategies, such as enhancing landscape connectivity.

Conservation value of dispersed tree cover threatened by pasture management

Trees dispersed in pastures are a prominent feature of many Central American landscapes, particularly in cattle producing regions where farmers retain trees to serve as shade, fodder, timber and firewood. The presence of dispersed trees in pastures is often considered as important for the conservation of biodiversity by providing habitat and enhancing landscape connectivity. However, despite their critical productive and environmental roles, little is known about tree distribution within pastures or how farmers’ management decisions influence the trees themselves and their impact on farm productivity and biodiversity conservation. Here, we present a synthesis of (a) the abundance, composition, and size of dispersed trees in four important cattle producing regions of Costa Rica (Caňas and Río Frío) and Nicaragua (Rivas and Matiguás), based on inventory of 18,669 trees on 1492 ha of pasture, (b) the local knowledge, management and use of trees by cattle farmers, and (c) opportunities for ensuring sustainable management of dispersed trees in pasture-dominated landscapes. Dispersed trees were common in all four landscapes, with mean frequency ranging from 8.0 trees ha −1 in Caňas to 33.4 trees ha −1 in Matiguás. A total of 255 tree species were found in pastures across the four landscapes. The total number of tree species per landscape varied from 72 in Rivas to 101 in Caňas and Rio Frio, with mean species richness per farm ranging from 22.9 in Rio Frio to 45.9 in Matiguás. In all four landscapes, a handful of tree species dominated the pastures, with the ten most abundant species in each landscape accounting for >70% of all trees recorded. Most of these common tree species provide fruits or foliage eaten by cattle, or are important timber or firewood species, and are deliberately retained by farmers for these uses. In all four landscapes, farmers had a detailed knowledge of tree attributes affecting pasture and animal productivity, and influenced tree cover through pasture management activities and occasional tree cutting. Current farm management practices are gradually decreasing the diversity of trees in pastures, and in some cases also tree density, reducing their contribution to farm productivity and biodiversity conservation. To reverse this trend, incentives are required to encourage cattle farmers to retain and enhance tree cover in pastures, through the adoption of pasture management practices that favor the regeneration and persistence of a diverse range of tree species.

Native trees and shrubs for the productive rehabilitation of tropical cattle ranching lands

Extensive cattle production currently occupies more than 27% of the rural landscapes in Latin America, and continues to expand. This activity, deeply rooted in the culture and rural economy of the region, requires an urgent transformation if it is to become both more efficient and environmentally friendly. Silvopastoral systems that incorporate native trees and shrubs are instrumental for the productive rehabilitation of cattle production and for biodiversity conservation in agricultural landscapes. We discuss research progress and adoption of intensive silvopastoral systems in Colombia and Mexico. Intensive silvopastoral systems (ISS) are a sustainable form of agroforestry for livestock production that combines fodder shrubs planted at high densities (more than 10,000 plants ha −1), trees and palms, and improved pastures. High stocking and the natural production of milk and meat in these systems are achieved through rotational grazing with electric fencing and a permanent supply of water for the cattle. While milk and meat production and cattle reproduction are enhanced, production costs decline as external inputs are replaced by natural processes related to fertility and biological control. We also discuss the importance of the ISS with native trees for climate change adaptation and mitigation, the barriers for their adoption, and how these have been successfully addressed using payment for environmental services, special credits and technical assistance. Finally, we highlight the need for enhancing landscape connectivity by integrating SPS to conservation corridors with native species to promote biodiversity conservation and other environmental services demanded by society.

Linking genetic diversity, mating patterns and progeny performance in fragmented populations of a Mediterranean shrub

Summary 1. The long‐term persistence of fragmented plant populations is predicted to be threatened by a loss of genetic variability and increasing inbreeding, which might lower offspring fitness through inbreeding depression. Assessing plant progeny performance together with measurements of genetic diversity and mating patterns is therefore essential in the understanding of the role of the historical (i.e. genetic diversity in adults) and contemporary (i.e. current mating patterns) genetic effects of fragmentation on inbreeding depression, thus, on recruitment potential. 2. We evaluated genetic diversity, mating patterns and progeny performance at different life stages in seven populations of a Mediterranean shrub (myrtle Myrtus communis) that differed in size and degree of isolation (Large, Small‐connected and Small‐isolated populations). The study was conducted in the Guadalquivir Valley (SW Spain), a chronically and severely fragmented landscape characterized by c. 1% of woodland cover. 3. Parameters of genetic diversity (Ar, Ho and He) of adult plants were in general higher in the Large populations than in the two types of Small populations, which were similar. Outcrossing rates were higher in Small‐connected populations (mean: tm = 0·62), intermediate in Large (tm = 0·35) and lower in Small‐isolated populations (tm = 0·13), and were positively correlated with the genetic diversity of progenies. 4. Several measurements of progeny performance were higher in Small‐connected populations, intermediate in Large and lower in Small‐isolated populations, in particular those related with the quantity of viable seedlings produced (germination and survival). Outcrossing rates rather than the genetic diversity of adult plants were positively correlated with these measurements of progeny performance. 5. We thus conclude that contemporary mating patterns (outcrossing rates) have a more critical influence on progeny performance than either population fragmentation or the historical levels of genetic diversity. 6. Synthesis and applications. It may be possible to enhance either the fitness or certain levels of genetic diversity in progenies by promoting outcrossed matings in fragmented populations of self‐compatible plant species. In our study species, this would be feasible either by controlling honeybee Apis mellifera hives or maintaining and/or enhancing landscape connectivity around small patches.

Land rehabilitation and the conservation of birds in a degraded Afromontane landscape in northern Ethiopia

The few remaining Afromontane forest fragments in northern Ethiopia and the surrounding degraded, semiarid matrix form a habitat mosaic of varying suitability for forest birds. To evaluate the effect of recent land rehabilitation efforts on bird community composition and diversity, we studied bird species distributions in ten small forest fragments (0.40–20.95 ha), five grazing exclosures (10-year-old forest restoration areas without wood extraction and grazing livestock) and three grazed matrix sites during the rainy season (July–October 2004) using 277 one-hour species counts. Based on the distribution pattern of 146 bird species, sites were assigned to one of three bird communities (birds of moist forest, dry forest or degraded savanna), each occupying a well-defined position along an environmental gradient reflecting decreasing vegetation structure and density. All three communities were representative of the avifauna of Afrotropical Highland open forest and woodland with a high proportion of invasive and competitive generalist species (31%). Apart from these, exclosures shared more species with forest fragments (20%) than did the grazed matrix (5%), indicating local ecosystem recovery. By increasing habitat heterogeneity, exclosures have the potential to enhance landscape connectivity for forest birds and are, therefore, an effective instrument for conserving species in a fragmented landscape. However, 52 bird species (36%) occurred exclusively within forest patches and many forest birds that use exclosures are unlikely to maintain viable populations when forest fragments disappear, particularly as forest fragments may be a critical resource during the hot dry season. This highlights the high conservation value of small isolated forest fragments for less tolerant, forest-limited and/or biome-restricted species.

Biodiversity conservation in cocoa production landscapes: an overview

Cocoa agroforests that retain a floristically diverse and structurally complex shade canopy have the potential to harbour significant levels of biodiversity, yet few studies have documented the plant and animal species occurring within these systems or within landscapes dominated by cocoa production. In this special issue, we bring together nine studies from Latin America, Africa and Asia that document the contribution of cocoa agroforestry systems to biodiversity conservation, and explore how the design, management and location of these systems within the broader landscape influence their value as habitats, resources and biological corridors. Tree diversity within the cocoa production systems is variable, depending on management, cultural differences, location and farm history, among other factors. Animal diversity is typically highest in those cocoa agroforests that have high plant diversity, structurally complex canopies, and abundant surrounding forest cover. In general, both plant and animal diversity within cocoa agroforests is greater than those of other agricultural land uses, but lower than in the original forest habitat. There are several emerging threats to biodiversity conservation within cocoa production landscapes, including the loss of remaining forest cover, the simplification of cocoa shade canopies and the conversion of cocoa agroforestry systems to other agricultural land uses with lower biodiversity value. To counter these threats and conserve biodiversity over the long-term, land management should focus on conserving native forest habitat within cocoa production landscapes, maintaining or restoring floristically diverse and structurally complex shade canopies within cocoa agroforests, and retaining other types of on-farm tree cover to enhance landscape connectivity and habitat availability.