Showing papers in "Journal of Applied Ecology in 2010"

Distance software: design and analysis of distance sampling surveys for estimating population size.

Abstract: Summary 1. Distance sampling is a widely used technique for estimating the size or density of biological populations. Many distance sampling designs and most analyses use the software Distance. 2. We briefly review distance sampling and its assumptions, outline the history, structure and capabilities of Distance, and provide hints on its use. 3. Good survey design is a crucial prerequisite for obtaining reliable results. Distance has a survey design engine, with a built-in geographic information system, that allows properties of different proposed designs to be examined via simulation, and survey plans to be generated. 4. A first step in analysis of distance sampling data is modelling the probability of detection. Distance contains three increasingly sophisticated analysis engines for this: conventional distance sampling, which models detection probability as a function of distance from the transect and assumes all objects at zero distance are detected; multiple-covariate distance sampling, which allows covariates in addition to distance; and mark–recapture distance sampling, which relaxes the assumption of certain detection at zero distance. 5. All three engines allow estimation of density or abundance, stratified if required, with associated measures of precision calculated either analytically or via the bootstrap. 6. Advanced analysis topics covered include the use of multipliers to allow analysis of indirect surveys (such as dung or nest surveys), the density surface modelling analysis engine for spatial and habitat modelling, and information about accessing the analysis engines directly from other software. 7.Synthesis and applications. Distance sampling is a key method for producing abundance and density estimates in challenging field conditions. The theory underlying the methods continues to expand to cope with realistic estimation situations. In step with theoretical developments, state-of-the-art software that implements these methods is described that makes the methods accessible to practising ecologists.

The introduction of coastal infrastructure as a driver of change in marine environments

Abstract: Summary 1. Coastal landscapes are being transformed as a consequence of the increasing demand for urban infrastructure to sustain commercial, residential and tourist activities. A variety of man-made structures, such as breakwaters, jetties and seawalls have thus become ubiquitous features of intertidal and shallow subtidal habitats. This transformation will accelerate in response to the exponential growth of human populations and to global changes, such as sea-level rise and increased frequency of extreme meteorological events (e.g. storms). Here, we provide a critical overview of the major ecological effects of increasing infrastructure to marine habitats, we identify future research directions for advancing our understanding of marine urban ecosystems and we highlight how alternative management options might mitigate their impacts. 2. Urban infrastructure supports different epibiota and associated assemblages and does not function as surrogate of natural rocky habitats. Its introduction in the intertidal zone or in near-shore waters can cause fragmentation and loss of natural habitats. Furthermore, the provision of novel habitat (hard substrata) along sedimentary shores can alter local and regional biodiversity by modifying natural patterns of dispersal of species, or by facilitating the establishment and spread of exotic species. 3. Attempts to use ecological criteria to solve problems of urban infrastructure are promising. Incorporating natural elements of habitat (e.g. wetland vegetation; seagrass) into shoreline stabilization can reduce ecological impacts, without impinging on its efficacy in halting erosion. Likewise, improving the ecological value of artificial structures by adding features of habitat that are generally missing from such structures (e.g. rock-pools) can contribute to mitigation of the detrimental effects of urbanization on biodiversity. Management of anthropogenic disturbances (e.g. maintenance works; harvesting) to artificial habitat is, however, necessary if such attempts are to be successful. 4. Synthesis and applications. Increasing our understanding of the ecological functioning of marine habitats created by urban infrastructure and incorporating ecological criteria into coastal engineering are crucial for preserving biodiversity in the face of the growth of human populations in coastal areas and of forecasted global changes. Achieving this goal will need strong collaboration between engineers, managers and ecologists.

Defining and measuring ecological specialization

Abstract: Summary 1. Ecological specialization is one of the main concepts in ecology and conservation. However, this concept has become highly context-dependent and is now obscured by the great variability of existing definitions and methods used to characterize ecological specialization. 2. In this study, we clarify this concept by reviewing the strengths and limitations of different approaches commonly used to define and measure ecological specialization. We first show that ecological specialization can either be considered as reflecting species’ requirements or species’ impacts. We then explain how specialization depends on species-specific characteristics and on local and contingent environmental constraints. We further show why and how ecological specialization should be scaled across spatial and temporal scales, and from individuals to communities. 3. We then illustrate how this review can be used as a practical toolbox to classify widely used metrics of ecological specialization in applied ecology, depending on the question being addressed, the method used, and the data available. 4. Synthesis and applications. Clarifying ecological specialization is useful to make explicit connections between several fields of ecology using the niche concept. Defining this concept and its practical metrics is also a crucial step to better formulate predictions of scientific interest in ecology and conservation. Finally, understanding the different facets of ecological specialization should facilitate to investigate the causes and consequences of biotic homogenization and to derive relevant indicators of biodiversity responses to land-use changes.

The impact of proxy‐based methods on mapping the distribution of ecosystem services

Abstract: An increasing number of studies are examining the distribution and congruence of ecosystem services, often with the goal of identifying areas that will provide multiple ecosystem service 'hotspots'. However, there is a paucity of data on most ecosystem services, so proxies (e.g. estimates of a service for a particular land cover type) are frequently used to map their distribution. To date, there has been little attempt to quantify the effects of using proxies on distribution maps of ecosystem services, despite the potentially large errors associated with such data sets. 2. Here, we provide the first study examining the effects of using proxies on ecosystem service maps and the degree of spatial congruence of these maps with primary data, using England as a case study. 3. We show that land cover based proxies provide a poor fit to primary data surfaces for biodiversity, recreation and carbon storage, and that correlations between ecosystem services change depending on whether primary or proxy data are used for the analyses. 4. The poor fit of proxies to primary data was also evident when we selected hotspots of single ecosystem services, and consistency between raw and modelled surfaces was extremely low when considering the locations that were coincident hotspots for multiple services. 5. Synthesis and applications. Proxies may be suitable for identifying broad-scale trends in ecosystem services, but even relatively good proxies are likely to be unsuitable for identifying hotspots or priority areas for multiple services

Multiple stressors in agricultural streams: interactions among sediment addition, nutrient enrichment and water abstraction

Abstract: Summary 1. Many ecosystems are influenced simultaneously by multiple stressors, and the consequences of stressors are often unpredictable on the basis of knowledge of single effects. Agriculture affects streams world-wide via nutrient enrichment, elevated fine sediment and water abstraction for irrigation, but the combined impacts of these stressors are unknown. 2. We manipulated all three stressors simultaneously in an 18-day experiment and determined their individual and pair-wise combined effects on benthic invertebrates, algal biomass and leaf decay. We added nutrients (phosphorus plus nitrogen) and/or fine sediment (grain size 0·2 mm) to 18 experimental stream channels (dimensions 250 × 15 × 15 cm) supplied with water from a nearby stream. Three sediment and three nutrient treatments (high, intermediate, natural) were applied to each of six channels while flow was reduced by 80% in half the channels. Invertebrates (composition, abundance) and algae (chlorophyll a) were assayed using ceramic tile substrata and leaf decay was assayed using bundled leaves of a native shrub. Invertebrates colonizing leaf packs were also sampled. 3. Effects of sediment addition and flow reduction on biological response parameters were twice as common as nutrient enrichment effects. Nutrient enrichment increased total invertebrate abundance on tiles, algal biomass accrual and leaf decay rates, whereas both sediment addition (at the highest level) and flow reduction had mostly negative effects (e.g. reduced algal biomass, invertebrate abundance and/or taxonomic richness). 4. Stressors interacted often, and interactions between sediment and flow were particularly common. The negative impact of added sediment on aquatic biota was stronger at reduced flow, especially on tile substrata that were more exposed to the current than leaf-pack substrata. 5. Synthesis and applications. Our key findings imply that abstracting water from a stream already subjected to high fine sediment inputs may have far worse effects on the invertebrate fauna than abstraction from a similar stream with lower sediment levels. Aquatic resource managers should be aware of this important interaction between multiple stressors.

Beyond taxonomy: a review of macroinvertebrate trait‐based community descriptors as tools for freshwater biomonitoring

Abstract: Summary 1. Species traits have been frequently used in ecological studies in an attempt to develop a general ecological framework linking biological communities to habitat pressures. The trait approach offers a mechanistic alternative to traditional taxonomy-based descriptors. This review focuses on research employing traits as biomonitoring tools for freshwater ecosystems, although the lessons learned have wider application in the assessment of other ecosystem types. 2. We review the support from ecological theory to employ species traits for biomonitoring purposes (e.g. the habitat templet concept, landscape filtering hypothesis), and the subsequent studies that test the hypotheses arising from these theories, and apply this knowledge under real freshwater biomonitoring scenarios. We also include studies that deal with more specific issues such as trait trade-offs and trait syndromes. 3. We highlight the functional trait approach as one of the most promising tools emerging for biomonitoring freshwater ecosystems. Several technical issues are addressed and solutions are proposed. We discuss the need for: a broader unified trait biomonitoring tool; a more accurate understanding of the natural variation of community patterns of trait expression; approaches to diminish the effects of trait trade-offs and trait syndromes; additional life history and ecological requirement studies; and the detection of specific impacts under multiple stressor scenarios. 4. Synthesis and applications. This review provides biologists with the conceptual underpinning for the use of species traits as community descriptors and for freshwater biomonitoring and management. We expect that the functional trait approach will ultimately improve communication to managers and legislators of the importance of protecting freshwater ecosystem functions.

Partitioning variation in ecological communities: do the numbers add up?

Abstract: Summary 1. Statistical tests partitioning community variation into environmental and spatial components have been widely used to test ecological theories and explore the determinants of community structure for applied conservation questions. Despite the wide use of these tests, there is considerable debate about their relative effectiveness. 2. We used simulated communities to evaluate the most commonly employed tests that partition community variation: regression on distance matrices and canonical ordination using a third-order polynomial, principal components of neighbour matrices (PCNM) or Moran’s eigenvector maps (MEM) to model spatial components. Each test was evaluated under a variety of realistic sampling scenarios. 3. All tests failed to correctly model spatial and environmental components of variation, and in some cases produced biased estimates of the relative importance of components. Regression on distance matrices under-fit the spatial component, and ordination models consistently under-fit the environmental component. The PCNM and MEM approaches often produced inflated R2 statistics, apparently as a result of statistical artefacts involving selection of superfluous axes. This problem occurred regardless of the forward-selection technique used. 4. Both sample configuration and the underlying linear model used to analyse species–environment relationships also revealed strong potential to bias results. 5. Synthesis and applications. Several common applications of variation partitioning in ecology now appear inappropriate. These potentially include decisions for community conservation based on inferred relative strengths of niche and dispersal processes, inferred community responses to climate change, and numerous additional analyses that depend on precise results from multivariate variation-partitioning techniques. We clarify the appropriate uses of these analyses in research programmes, and outline potential steps to improve them.

Homogenization of lepidopteran communities in intensively cultivated agricultural landscapes

Abstract: Landscape simplification and habitat fragmentation may cause severe declines of less mobile and habitat specialist species and lead to biotic homogenization of species communities, but large-scale empirical evidence on biotic homogenization remains sparse. We sampled butterfly and day-active geometrid moth communities within 134 differently fragmented landscapes in Finland situated in five geographical regions. Overall species richness was partitioned into alpha and beta diversity and butterflies were assigned a species-specific mobility rank and habitat specificity score based on published ecological trait classifications. Alpha and beta diversity of butterflies and geometrid moths decreased with increasing agricultural intensity, independently of geographical position. The responses were either linear or nonlinear with accelerating decrease of diversity when arable field cover exceeded 60%. Mobility rank and percentage generalists of butterfly communities increased linearly with increasing field cover. In landscapes with high agricultural intensity (>60% field coverage), the decrease in beta diversity of butterflies was strongly associated with an increasing proportion of habitat generalists and increasing average mobility in the butterfly communities. However, there was no such relationship in landscapes with low or moderate agricultural intensity. Synthesis and applications. We demonstrate that biotic homogenization caused by land-use change arises as a consequence of the loss of habitat specialists and poor dispersers in intensively cultivated landscapes with simplified landscape structure. Agri-environment schemes will therefore be inefficient in protecting high beta diversity unless they explicitly increase habitat availability and connectivity for habitat specialists and poor dispersers. © 2010 The Authors. Journal compilation © 2010 British Ecological Society. (Less)

Individual responses of seabirds to commercial fisheries revealed using GPS tracking, stable isotopes and vessel monitoring systems

Abstract: Summary 1. The large amount of discards produced by commercial fisheries can have major impacts on marine predator populations: this abundant food may increase populations of some scavengers or decrease others via accidental bycatch. Yet, despite the conservation implications of discard practices, the ecology of individual scavengers is poorly understood. 2. Here, we assess the influence of commercial fisheries’ activity on the foraging behaviour of individual breeding northern gannets Morus bassanus. Using recent developments in stable isotope mixing models (Stable Isotope Analysis inR or SIAR) we estimate individual discard consumption. Using GPS tracking and the Vessel Monitoring System (VMS), we investigate behavioural responses to trawlers. 3. Analysis of conventional diet samples, as well as stable isotope ratios of carbon and nitrogen in blood (plasma and cells), highlight marked individual differences in the proportion of fishery discards in the diet. Individual differences in foraging behaviour revealed by stable isotopes show evidence of both short-termconsistency and behavioural flexibility. 4. At-sea path tortuosity of 25 gannets (tracked using GPS loggers) revealed scale-dependent adjustments in response to VMS-derived fishing vessel locations, as well as to sea surface temperature, chlorophyll a concentration and copepod abundance. The results also indicate individual variability in behavioural response to trawlers. 5. Individual differences in the amount of discards estimated from SIAR were negatively correlated with differences in foraging trip length and body condition, indicating potential fitness consequences. 6. Synthesis and applications. The management of commercial fisheries and apex predators is a daunting task. Ultimately, reducing bycatch and removing dependency on discards remain key conservation priorities, but managers should also ensure that scavenging species have sufficient alternative food to meet their energetic needs, to ameliorate potential unforeseen knock-on consequences. The results of Stable Isotope Analysis (SIAR) reveal intra-population differences in discard consumption by gannets; differences that have impacts on foraging effort and body condition. The use of GPS tracking and Vessel Monitoring Systems (VMS) reveal that gannet at-sea behaviour is influenced by fishing vessels, although this also varies among individuals. A combination of SIAR, GPS tracking and VMS can be used to study fishery ⁄ scavenger interactions in detail at the individual level, to answer fundamental questions about scavenging behaviour.

Pollination services decline with distance from natural habitat even in biodiversity-rich areas

Abstract: Summary 1. There is considerable evidence for the negative impacts of habitat alteration on pollinators in highly disturbed regions of the world. However, it remains unclear whether these findings reflect a global crisis for crop pollination. Understanding the extent to which world agriculture is endangered by pollinator decline is essential if the economic valuation of nature is to be used to promote conservation. 2. We assess the susceptibility to pollinator limitation of one of the most important tropical and subtropical fruit crops, mango Mangifera indica L., commonly planted in a region of South Africa located between two large biodiversity-rich protected natural areas. We conducted flower visitor surveys, exclusion experiments and spatial analysis of flower visitation and fruit production patterns. 3. Our results show that both ants and flower visitors were effective pollinators of mango, the latter significantly declining (in abundance and species richness) with distance to natural habitat while ants were not affected. Neither the absence of pesticides nor the supplementation of flower visitors by using managed honeybees served to offset these negative impacts. Food-web data suggest that maintaining diversity of flower resources within farmland can help maintain pollinator communities. 4. Moreover, models based exclusively on pollinator abundance underestimated the negative effect of distance from natural habitat on production (42% less at 500 m from natural habitat). As soil nutrient levels and water content are regularly measured and corrected in all study sites, these results suggest that pollinator diversity may also be important. 5. Synthesis and applications. This study provides one of the first examples of marked pollination limitation in farms surrounded by well-protected natural habitat. For mango farming to be sustainable, it is essential to limit contiguous growth of farmland and consider practices that restore the complexity of plant-pollinator networks within farms, for example through the creation and maintenance of pollinator-friendly areas. By highlighting the economic gains of adopting pollinator-friendly practices in agriculture, this work contributes to a growing body of studies that reveal that making farmland more suitable for pollinators benefits both agriculture and nature conservation.

Spontaneous succession in limestone quarries as an effective restoration tool for endangered arthropods and plants

Abstract: Summary 1. The view of post-mining sites is rapidly changing among ecologists and conservationists, as sensitive restoration using spontaneous succession may turn such sites into biodiversity refuges in human-exploited regions. However, technical reclamation, consisting of covering the sites by topsoil, sowing fast-growing herb mixtures and planting trees, is still commonly adopted. Until now, no multi-taxa study has compared technically reclaimed sites and sites left with spontaneous succession. 2. We sampled communities of vascular plants and 10 arthropod groups in technically reclaimed and spontaneously restored plots in limestone quarries in the Bohemian Karst, Czech Republic. For comparison, we used paired t-tests and multivariate methods, emphasizing red-list status and habitat specialization of individual species. 3. We recorded 692 species of target taxa, with a high proportion of red-listed (10%) and xeric specialist (14%) species, corroborating the great conservation potential of the quarries. 4. Spontaneously restored post-mining sites did not differ in species richness from the technical reclaimed sites but they supported more rare species. The microhabitat cover of leaf litter, herbs and moss, were all directly influenced by the addition of topsoil during reclamation. 5.Synthesis and applications. Our results show that the high conservation potential of limestone quarries could be realized by allowing succession to progress spontaneously with minimal intervention. Given the threat to semi-natural sparsely vegetated habitats in many regions, active restoration measures at post-mining sites should be limited to maintenance of early successional stages, instead of acceleration of succession.

MINI‐REVIEW: Habitat analogues for reconciliation ecology in urban and industrial environments

Abstract: Summary 1. Current views of anthropogenic environments emphasize the extreme novelty of urban and industrial ecosystems. Proponents of reconciliation ecology argue that we need to use such habitats to conserve biodiversity, given the inadequacy of natural reserve systems. 2. Some of the harshest anthropogenic ecosystems may be able to support indigenous biodiversity due to their structural or functional resemblance to natural ecosystems, habitats, or microsites that may be present in the region but not part of the historic ecosystem on a particular site. Here we review recent work that evaluates similarities between urban and industrial ecosystems and natural analogues, and explore the potential for these in reconciliation ecology. 3. We find that artificial habitats represent a gradient of ecological novelty which may be independent of the degree of human influence. While hard-surfaced habitats such as walls and quarries are the most investigated artificial analogues (of natural rock pavements and cliffs), there are many other examples spanning a range of habitats in both terrestrial and marine settings. Analogous ecosystems may be present in the region but limits to dispersal can prevent appropriate species from reaching urban or industrial sites, and small differences in abiotic conditions can sometimes prevent colonization by native biota in otherwise similar artificial habitats. We suggest that a search for habitat analogues represents an important principle to guide reconciliation ecology in urban and industrial lands. In constrast, analogous ecosystems may also support pest species that exploit the similarities between anthropogenic habitats and their ancestral habitats. 4. Synthesis and applications. Identifying analogous habitats and ecosystems could enhance biodiversity conservation and ecosystem services in anthropogenic environments. Abiotic and biotic differences between artificial analogues and natural systems can be frequently overcome by ecological engineering to make the environment more suitable for native biodiversity, and ⁄ or assisted dispersal to allow suitable native organisms to reach appropriate sites within artificial ecosystems. Altering some habitats to become less analogous may help reduce impacts of pest species in urban and industrial areas.

Ground validation of presence‐only modelling with rare species: a case study on barbastelles Barbastella barbastellus (Chiroptera: Vespertilionidae)

Abstract: Summary 1. We evaluated the accuracy of presence-only modelling for predicting the distribution of rare species, when data are scarce and usually collected with sampling biases. We modelled the potential distribution in Portugal of one of the rarest European bats Barbastella barbastellus and subsequently ground-validated predictions by using acoustic transects. 2. We used ecological niche factor analysis (ENFA) and maximum entropy (Maxent) modelling to build distribution models of B. barbastellus, and determined which ecological factors were more relevant for each model. As ENFA only accepts continuous variables, we built one Maxent model using the same variables as ENFA and another using land cover as a categorical variable. 3. Ecological niche factor analysis and both Maxent models predicted similar areas of occurrence in central and northern regions of Portugal, although ENFA predicted suitable habitat over a wider range. Conversely, there was substantial disagreement on the location of high-suitability areas in the south. This could be a consequence of a different choice of important variables made by each model. Native woodland and average temperature were the most relevant variables for Maxent, while in ENFA B. barbastellus was linked to higher altitudes although avoiding production forests and infrastructures. 4. Threshold-independent and -dependent statistics showed that Maxent models outperformed ENFA, probably as a consequence of divergent predictions in the new areas of occurrence. Overall, 15 new B. barbastellus sites were discovered and known distribution was extended c. 100 km to the south. 5. Synthesis and applications. Our results support the use of presence-only modelling as an indispensible tool for survey design as shown by the discovery of B. barbastellus populations outside of the previously known range. ENFA seems to be more suited to determining a species’ potential distribution, although failing to extrapolate it. In contrast, Maxent is better suited to determining a species’ realized distribution. It was successful in predicting occurrence in previously unsurveyed areas and can be recommended as a technique for determination of a conservative distribution for a species. Maxent modelling would greatly aid biodiversity conservation, especially when it is necessary to develop survey plans or first assessments of a species’ distribution.

Climate change and range expansion of an aggressive bark beetle: evidence of higher beetle reproduction in naïve host tree populations

Abstract: Summary 1. Hosts may evolve defences that make them less susceptible and suitable to herbivores impacting their fitness. Due to climate change-driven range expansion, herbivores are encountering naive host populations with increasing frequency. 2. Aggressive bark beetles are among the most important agents of disturbance in coniferous forest ecosystems. The presence of bark beetle outbreaks in areas with a historically unsuitable climate, in part a consequence of climate change, provided an opportunity to assess the hypothesis that the mountain pine beetle Dendroctonus ponderosae has higher reproductive success in lodgepole pine Pinus contorta trees growing in areas that have not previously experienced frequent outbreaks. 3. We felled and sampled mountain pine beetle-killed trees from historically climatically suitable and unsuitable areas, i.e. areas with and without a historical probability of frequent outbreaks. Reproductive success was determined from a total of 166 trees from 14 stands. 4. Brood productivity was significantly affected by climatic suitability class, such that mean brood production per female increased as historical climatic suitability decreased. 5. Synthesis and applications. The current study demonstrates that the mountain pine beetle has higher reproductive success in areas where its host trees have not experienced frequent beetle epi- demics, which includes much of the current outbreak area in north central British Columbia. This increased productivity of mountain pine beetle is likely to have been a key reason for the rapid pop- ulation buildup that resulted in unprecedented host tree mortality over huge areas in western Canada. The outbreak thus provides an example of how climate change-driven range expansion of native forest insects can have potentially disastrous consequences. Since an increased reproductive success is likely to accelerate the progression of outbreaks, it is particularly critical to manage forests for the maintenance of a mosaic of species and age classes at the landscape level in areas where host tree populations are naive to eruptive herbivores.

Environmental monitoring: the scale and speed of implementation varies according to the degree of peoples involvement

Abstract: Summary 1. Solutions to the global environmental crisis require scientific knowledge and responses spanning di! erent spatial scales and levels of societal organization; yet understanding how to translate environmental knowledgeintodecision-making andaction remainslimited. 2. We examined 104 published environmental monitoring schemes to assess whether participation indatacollection and analysisinfluencesthespeed and scaleof decision-makingandaction. 3. Our results show that scientist-executed monitoring informs decisions within regions, nations andinternationalconventions. However,decisionstypicallytake3‐9 yearstobe implemented. 4. Wealsoshowthatscientist-executedmonitoringhaslittleimpactatthevillagescale,wheremany natural resourcemanagement decisionsaremade. 5. At the village scale, monitoring schemes that involve local people, and relate to resource utilization at the village level, are much more e! ective at influencing decisions; these decisions typically take0‐1yeartobeimplemented. 6. Synthesis and applications: Involving local stakeholders in monitoring enhances management responses at local spatial scales, and increases the speed of decision-making to tackle environmental challengesatoperationallevelsofresourcemanagement.

Effects of land use at a landscape scale on bumblebee nest density and survival

Abstract: 1. We have little idea how landscape-scale factors influence the success of wild bumblebee nests over time. Here for the first time we use molecular markers to estimate within-season changes in the numbers of nests. 2. Workers of two bumblebee species were sampled in an arable landscape in late May–June and late July–August, and the numbers of nests represented in each sample were estimated. We compare the methods available to estimate nest number from such samples and conclude that methods which allow for heterogeneity in the probability of capture of nests provide the best fit to our data. Changes in numbers of nests at the two time points were used to infer nest survival. 3. The two bee species appeared to differ markedly in survival over time, with estimates of 45% of nests surviving for Bombus lapidarius and 91% for B. pascuorum. However, our data suggest that the foraging range of B. pascuorum may be greater in late season, which would lead us to overestimate nest survival in this species. Differential survival may also reflect differences in phenology between the two species. 4. The land use class which had the most consistent effects on nest number and survival was gardens; for B. lapidarius, the area of gardens within a 750 and 1000 m radius positively influenced nest survival, while for B. pascuorum, the number of nests in late samples was higher at sites with more gardens within a 500 and 750-m radius. For B. pascuorum, the area of grassland within a 250 and 500-m radius also positively influenced nest number in late samples, probably because this is the preferred nesting habitat for this species. 5. The importance of gardens is in accordance with previous studies which suggest that they now provide a stronghold for bumblebees in an otherwise impoverished agricultural environment; furthermore, our data suggest that the positive influence of gardens on bumblebee populations can spill over at least 1 km into surrounding farmland. 6. Synthesis and applications. The substantial effects that even small areas of local resources such as rough grassland or clover leys can have on bumblebee nest numbers and survival is of clear relevance for the design of pollinator management strategies.

Changes in breeding success and abundance of ground‐nesting moorland birds in relation to the experimental deployment of legal predator control

Abstract: Summary 1. An 8-year-field experiment on moorland in northern England manipulated the abundance of legally controllable predators whilst maintaining consistent habitat conditions. Subsequent changes in both the breeding success and abundance of five ground-nesting bird species were monitored: lapwing Vanellus vanellus, golden plover Pluvialis apricaria, curlew Numenius arquata, red grouse Lagopus lagopus scoticus and meadow pipit Anthus pratensis and the abundance only of snipe Gallinago gallinago and skylark Alauda arvensis. 2. Control of fox Vulpes vulpes, carrion crow Corvus corone, stoat Mustela ermina and weasel Mustela nivalis reduced the abundance of fox (−43%) and crow (−78%); no changes were detected in already low stoat or weasel abundances. 3. Reductions in foxes and crows led to an average threefold increase in breeding success of lapwing, golden plover, curlew, red grouse and meadow pipit. 4. Predator control led to subsequent increases in breeding numbers (≥14% per annum) of lapwing, curlew, golden plover and red grouse, all of which declined in the absence of predator control (≥17% per annum). 5. Synthesis and applications. Controlling predators is a potentially important management tool for conserving a range of threatened species. Considerable sums of public monies are currently spent on habitat improvement for conservation and some of these public funds should be used to underpin habitat works with predator removal.

Butterfly and plant specialists suffer from reduced connectivity in fragmented landscapes

Abstract: Summary 1. Calcareous grasslands are diversity hotspots for plant and butterfly species in Europe, but connectivity of these grasslands has been reduced by habitat loss and fragmentation in recent decades. Reduced habitat area leads to biodiversity loss, but the significance of habitat connectivity independent of patch size and habitat quality is unclear. 2. Here, we focus on the impact of habitat connectivity on both butterfly and plant species richness and compare (i) a connectivity index, (ii) percentage habitat cover and (iii) distance to the next suitable habitat patch as alternative measures of connectivity. Species were recorded in 2007 in northern Bavaria (Germany) in paired large and small study sites in 31 independent landscapes. 3. We found that total loss of grassland connectivity would reduce species richness of specialist butterflies (38–69%) and specialist plants (24–37%). A connectivity index combining patch size and distance in the surrounding landscape was a better measure of connectivity than percentage habitat cover or distance to the next suitable habitat. 4. Species richness, species density and abundance of habitat-specialist butterflies and plants were significantly higher in large compared with small study sites. 5.Synthesis and applications. We conclude that connectivity is highly relevant for conservation of butterfly and plant species with specialized habitat requirements, but the decision as to which connectivity measure is most appropriate depends on patch configuration, landscape context and study design. We suggest that management strategies should aim to increase connectivity by active restoration of former calcareous grasslands to ensure long-term survival of habitat-specialist species.

Sanitary versus environmental policies: fitting together two pieces of the puzzle of European vulture conservation.

Abstract: Summary 1. Between 1996 and 2000 the appearance of bovine spongiform encephalopathy swiftly became one of the most serious public health and political crises concerning food safety ever experienced in the European Union (EU). Subsequent sanitary regulations led to profound changes in the management of livestock carcasses (i.e. the industrial destruction of around 80% of all animal carcasses), thereby threatening the last remaining healthy scavenger populations of the Old World and thus contradicting the long-term environmental policies of the EU. 2. Several warning signs such as a decrease in breeding success, an apparent increase in mortality in young age classes of vultures and an increase in the number of cases of vultures attacking and killing cattle, as well as a halt in population growth, suggest that the decrease in the availability of food resources has had harmful effects on vulture populations. 3. Between 2002 and 2005, a number of dispositions to the EU regulations (2003 ⁄ 322 ⁄ CE 2005 ⁄ 830 ⁄ CE) enabled conservation managers to adopt rapid solutions (i.e. the creation of vulture restaurants) aimed at satisfying the food requirements of vultures. However, these conservation measures may seriously modify habitat quality and have indirect detrimental effects on avian scavenger populations and communities. 4. Synthesis and applications. Conservation managers and policy-makers need to balance the demands of public health protection and the long-term conservation of biodiversity. The regulations concerning carrion provisioning need to be more flexible and there needs to be greater compatibility between sanitary and environmental policies. We advocate policies that authorize the abandonment of livestock carcasses and favours populations of wild herbivores to help to maintain populations of avian scavengers. Conservation strategies should be incorporated into new European Commission regulations, which should be effective in 2011.

Fire management in Mediterranean-climate shrublands: a case study from the Cape fynbos, South Africa

Abstract: CITATION: Van Wilgen, B W et al 2010 Fire management in Mediterranean-climate shrublands: a case study from the Cape fynbos, South Africa Journal of Applied Ecology, 47(3):631–638, doi: 101111/j1365-2664201001800x

A comparative analysis of restoration measures and their effects on hydromorphology and benthic invertebrates in 26 central and southern European rivers

Abstract: 1. Hydromorphological river restoration usually leads to habitat diversification, but the effects on benthic invertebrates, which are frequently used to assess river ecological status, are minor. We compared the effects of river restoration on morphology and benthic invertebrates by investigating 26 pairs of non-restored and restored sections of rivers in Austria, Czech Republic, Germany, Italy and the Netherlands. 2. Sites were grouped according to (1) region: central Europe vs. southern Europe; (2) river type: mountain vs. lowland rivers; (3) restoration approach: active vs. passive restoration and (4) a combination of these parameters. All sites were sampled according to the same field protocol comprising hydromorphological surveys of river and floodplain mesohabitats, microhabitats at the river bottom and habitat-specific sampling of benthic invertebrates. Restoration effects were compared using Shannon–Wiener Indices (SWIs) of mesohabitats, microhabitats and invertebrate communities. Differences in metric values between non-restored and restored sites were compared for 16 metrics that evaluated hydromorphology and the benthic invertebrate community. 3. Mean SWIs differed for both mesohabitats (1·1 non-restored, 1·7 restored) and microhabitats (1·0 non-restored, 1·3 restored), while SWIs for invertebrate communities were not significantly different (2·4 non-restored, 2·3 restored). Meso- and microhabitat metrics in the restored sections were usually higher compared with the non-restored sections, but the effects on invertebrate metrics were negligible. 4. Measures in southern Europe and mountainous regions yielded larger differences between non-restored and restored sections of rivers. Differences in the meso- and microhabitat metrics were largest for actively restored sections of central European mountain rivers and rivers from southern Europe, followed by passively restored mountain rivers in central Europe. The smallest differences were observed for lowland sites. There was no significant restoration effect on invertebrate metrics in any categories. 5. Synthesis and applications. Restoration measures addressing relatively short river sections (several hundred metres) are successful in terms of improving habitat diversity of the river and its floodplain. Active restoration measures are suitable if short-term changes in hydromorphology are desired. To realize changes in benthic invertebrate community composition, habitat restoration within a small stretch is generally not sufficient. We conclude that restoring habitat on a larger scale, using more comprehensive measures and tackling catchment-wide problems (e.g. water quality, source populations) are required for a recovery of the invertebrate community.

Pollination services provided to small and large highbush blueberry fields by wild and managed bees

Abstract: 1 Plantings of pollinator-dependent crops vary from large, intensively managed fields to small fields that are managed less intensively, yet there is relatively little information on how pollinator populations and their contribution to crop productivity vary across this gradient 2 We determined the relative importance of wild bees and managed honey bees Apis mellifera L for crop pollination in the blueberry Vaccinium corymbosum L system of Michigan, USA, by comparing bee communities in small, isolated blueberry fields with those in large blueberry fields (stocked with managed honey bee hives) and measuring the difference in yields of open-pollinated and pollinator-excluded clusters of flowers We combined these assessments to calculate the contribution of bees to crop production in this system 3 Wild bees were the dominant pollinators in small fields, comprising 58% of flower-visiting bees, whereas 97% of bees in large fields were honey bees Large fields had four times as many bees visiting flowers than small fields, but only one-tenth as many bumble bees as small fields 4 Levels of fruit set exceeded 85% in all fields and were similar between field sizes Berry weight increased with flower exposure to pollinators and was positively correlated with bee abundance Berry weights from open-pollinated flowers were twice as high in large fields compared with small fields 5 By combining berry weight increases attributable to honey bees and wild bees in blueberry fields with measurements of the bee community adjusted for pollinator efficiency, we calculated the relative contributions of honey bees and wild bees to pollination of Michigan blueberries We estimate that wild bees provide 82% of the pollination in small fields but only 12% of the total pollination services across this system, mostly through their secondary role in large fields 6 Synthesis and applications Wild bees are the primary pollinators of small blueberry fields, but these insects are at low abundance in large fields, perhaps due to a lack of nesting resources or competition for resources with honey bees Our findings highlight the dependence of commercial fruit producers on honey bees and suggest that increasing the pollination contribution of other bees, particularly bumble bees, in large fields will require that growers adopt wild bee conservation strategies or stock their fields with managed colonies Quantifying the contributions of managed and wild pollinating bees across the range of crop production scenarios will help to direct development of integrated crop pollination strategies to minimize the risk of pollination deficits affecting food production

Convergence and divergence in plant community trajectories as a framework for monitoring wetland restoration progress

Abstract: Summary 1. Environmental policies that use ecological restoration to offset the destruction of natural ecosystems assume that restorations readily compensate for the losses because they progress reliably and predictably over time, following deterministic successional trajectories. However, succession and restoration are spatially and historically contingent processes, often characterized by divergent trajectories that deviate from expectations. 2. We develop a framework for monitoring restorations that integrates two ideas from succession theory: convergence vs. divergence in species composition among successional sites, and progression towards vs. deviation from an expected community state. We apply this framework to short- and long-term monitoring data from 11 restored wetlands in Illinois, USA, by comparing plant species composition among restored wetlands over time and between restored wetlands and two sets of reference wetlands (high integrity, ‘target’ wetlands and low integrity, degraded wetlands). 3. Over the first 4 years, restored wetlands that were initially similar in species composition diverged, progressing towards different high integrity target states. Planting a large number of native species in restorations increased their similarity to reference wetlands. 4. Over longer time scales (5–11 years post-restoration), however, restored wetlands deviated from the ideal trajectory and converged upon the species composition of degraded wetlands, mainly because of non-native species invasion. 5. Synthesis and applications. Framing restoration trajectories in terms of compositional convergence/divergence and progression towards/deviation from an acceptable range of reference sites is useful for monitoring restoration progress, identifying constraints to success and predicting restoration outcomes. Barriers to restoration, including non-native species and a lack of native propagules, can limit long-term progression towards target communities and constrain restoration to undesirable outcomes. Furthermore, convergence of restored wetlands on an undesirable community state limits the effectiveness of wetland mitigation policies.

Habitat degradation and the decline of the threatened mussel Margaritifera margaritifera: influence of turbidity and sedimentation on the mussel and its host.

Abstract: Summary1. Habitatdegradationisamajorreasonforspeciesextinctions.Forparasite–hostinteractions,thedecline of a parasite may not only be related to the parasite’s tolerance to habitat degradation butalsoindirectlythroughthehost’stolerancetothesamedisturbance.2. Our objective was to explore the cause of population declines of the freshwater pearl musselMargaritiferamargaritiferabyrelatingtheagedistribution, densityandgrowthofthemusselswithturbidity, sedimentation rates and density of the mussel’s host, trout Salmo trutta, in 26 Swedishstreams.3. An analysis of the age structure of nine mussel populations showed that maximum age differedby60 years,withfivepopulationshavinglowproportionsofjuvenilemussels.Adultmusseldensitywashigheratsiteswherejuvenilemusselsoccurredthanatsiteslackingjuvenilemussels.4. Growth of adult mussels during the past 10 years was lower in the five streams lacking recentrecruitment than in the four streams with recent recruitment, indicating that some environmentalfactormaybenegativelyimpactingthesepopulations.5. Acomparisonamong24populationsindicatedthatturbidityandsedimentationmayberespon-sible for recruitment failure in 58% of the populations. The age of the youngest mussel was posi-tively related to turbidity and sedimentation, and juvenile mussel density was negatively related toturbidity and sedimentation. Incontrast,trout densitywasnot relatedtorecruitment ofmussels orsedimentation, but was positively related to turbidity in all streams, both with and without recentmusselrecruitment.6. Synthesis and applications. Recruitment failure of M. margaritifera appearstoberelatedtoitsown vulnerability to turbidity and sedimentation rather than to its host’s response to this type ofhabitatdegradation.Theresultsfromourstudysuggestthatmanagersmightbeabletoevaluatethepotential viability of mussel populations by measuring stream turbidity. Restoration activities toimprovethemussels’environmentshouldfocusonreducingfinematerialtransportintostreams.Key-words: habitat degradation, host–parasite, Margaritifera margaritifera, recruitment,Salmo trutta, sedimentation, turbidity, UnionoidaIntroduction

Potential spread of highly pathogenic avian influenza H5N1 by wildfowl: dispersal ranges and rates determined from large-scale satellite telemetry

Abstract: Summary 1. Migratory birds are major candidates for long-distance dispersal of zoonotic pathogens. In recent years, wildfowl have been suspected of contributing to the rapid geographic spread of the highly pathogenic avian influenza (HPAI) H5N1 virus. Experimental infection studies reveal that some wild ducks, geese and swans shed this virus asymptomatically and hence have the potential to spread it as they move. 2. We evaluate the dispersive potential of HPAI H5N1 viruses by wildfowl through an analysis of the movement range and movement rate of birds monitored by satellite telemetry in relation to the apparent asymptomatic infection duration (AID) measured in experimental studies. We analysed the first large-scale data set of wildfowl movements, including 228 birds from 19 species monitored by satellite telemetry in 2006–2009, over HPAI H5N1 affected regions of Asia, Europe and Africa. 3. Our results indicate that individual migratory wildfowl have the potential to disperse HPAI H5N1 over extensive distances, being able to perform movements of up to 2900 km within timeframes compatible with the duration of asymptomatic infection. 4. However, the likelihood of such virus dispersal over long distances by individual wildfowl is low: we estimate that for an individual migratory bird there are, on average, only 5–15 days per year when infection could result in the dispersal of HPAI H5N1 virus over 500 km. 5. Staging at stopover sites during migration is typically longer than the period of infection and viral shedding, preventing birds from dispersing a virus over several consecutive but interrupted long-distance movements. Intercontinental virus dispersion would therefore probably require relay transmission between a series of successively infected migratory birds. 6. Synthesis and applications. Our results provide a detailed quantitative assessment of the dispersive potential of HPAI H5N1 virus by selected migratory birds. Such dispersive potential rests on the assumption that free-living wildfowl will respond analogously to captive, experimentallyinfected birds, and that asymptomatic infection will not alter their movement abilities. Our approach of combining experimental exposure data and telemetry information provides an analytical framework for quantifying the risk of spread of avian-borne diseases.

Matrix models for a changeable world: the importance of transient dynamics in population management

Abstract: 1. Matrix population models are tools for elucidating the association between demographic processes and population dynamics. A large amount of useful theory pivots on the assumption of equilibrium dynamics. The preceding transient is, however, of genuine conservation concern as it encompasses the short-term impact of natural or anthropogenic disturbance on the population. 2. We review recent theoretical advances in deterministic transient analysis of matrix projection models, considering how disturbance can alter population dynamics by provoking a new population trajectory. 3. We illustrate these impacts using plant and vertebrate systems across contiguous and fragmented landscapes. 4. Short-term responses are of fundamental relevance for applied ecology, because the time-scale of transient effects is often similar to the length of many conservation projects. Investigation of the immediate, post-disturbance phase is vital for understanding how population processes respond to widespread disturbance in the short- and into the long term. 5. Synthesis and applications. Transient analysis is critical for understanding and predicting the consequences of management activities. By considering short-term population responses to perturbations, especially in long-lived species, managers can develop more informed strategies for species harvesting or controlling of invasive species.

Interference competition at the landscape level: the effect of free-ranging dogs on a native mesocarnivore

Abstract: Summary 1. Free-ranging domestic dogs are the world’s most common carnivore and can negatively interact with native wildlife at multiple levels. Yet the intraguild competitive effects of dogs on the distribution and habitat use of native carnivores are poorly known, especially in areas of conservation concern. 2. We examined the spatial distribution of sympatric populations of radiocollared Indian foxes and free-ranging dogs to determine if Indian foxes alter their habitat use in the presence of dogs. We tested the effects of landcover type, primary prey abundance (rodents) and the presence of dogs as predictors of Indian fox spatial distribution in a threatened grassland habitat in central India. 3. By counting rodent burrows, we determined that the relative abundance of rodents was higher in fallow land and agricultural land compared to natural grasslands. From radiotelemetry data, we determined that the presence of dogs was closely linked to human-modified habitats, such as agricultural land and human settlements. 4. Top ranked models, based on Akaike’s Information Criterion corrected for small sample size, indicated that the negative effects of the presence of dogs and agricultural land, and the positive effects of the presence of grassland and fallow land habitats were the strongest predictors of Indian fox spatial distribution. Thus, the use of the landscape by Indian foxes was determined not only by habitat type, but also by the presence of a mid-sized carnivore, the dog. 5. Synthesis and applications. Our results show that the presence of domestic dogs on the periphery of natural habitats can interfere with the spatial distribution of a sympatric carnivore. Vaccination and sterilization programmes, aimed at reducing population sizes and pathogen prevalence, do not restrict the free-ranging behaviour of dogs. Therefore, in areas of conservation value, control of free-ranging dogs would be required to fully mitigate the deleterious effects of dogs on native carnivores and other wildlife.

Abrupt spatial and numerical responses of overabundant foxes to a reduction in anthropogenic resources

Abstract: 1. Carnivore overabundance that results from exploitation of human derived resources can have numerous detrimental effects on local human populations and ecological communities. Experimental studies on the responses of overabundant carnivores to reductions of such resources are necessary to understand the effectiveness and impacts of resource reduction.

Do changes in the frequency, magnitude and timing of extreme climatic events threaten the population viability of coastal birds?

Abstract: Summary 1 Climate change encompasses changes in both the means and the extremes of climatic variables, but the population consequences of the latter are intrinsically difficult to study 2 We investigated whether the frequency, magnitude and timing of rare but catastrophic flooding events have changed over time in Europe’s largest estuary Subsequently, we quantified how this has affected the flooding risk of six saltmarsh nesting bird species 3 We show that maximum high tide has increased twice as fast as mean high tide over the past four decades (0AE 8v s 0AE 4c m year )1 ), resulting in more frequent and more catastrophic flooding of nests, especially around the time when most eggs have just hatched 4 Using data on species’ nest elevations, on their timing of egg-laying and on the duration that their eggs and chicks are at risk from flooding, we show that flooding risks increased for all six studied species (even after accounting for compensatory land accretion) and this is expected to worsen in the near future if they do not adapt Moreover, our study provides the first evidence that increasing flooding risks have reduced the reproductive output below stable population levels in at least one species, the Eurasian oystercatcher Haematopus ostralegus 5 Sensitivity analyses show that currently birds would benefit most from adapting their nest-site selection to higher areas However, historically the lower marsh has been favoured for its proximity to the feeding grounds and for its low vegetation aiding predator detection 6 Synthesis and applications We argue that it is more difficult for birds to infer that habitat quality has decreased from changes in the frequency of rare and unpredictable extreme events than from trends in climatic means Consequently, at present the lower parts of the saltmarsh may function as an ecological trap The creation of new (ie low) saltmarshes – currently a restoration priority – may thus counteract the goal of increasing the avian biodiversity of an area Management tools to mitigate the effects of climate change, either by making the higher saltmarsh more attractive (mowing, predator control) or by reducing the flooding risk of the lower marsh (building elevated plots), await to be tested

Red flag for green spray: adverse trophic effects of Bti on breeding birds

Abstract: Summary 1. The expanding use of selective pest-control agents provides a unique opportunity to study food web interactions in the field while addressing major environmental issues. Bacillus thuringiensis israelensis (Bti) is the most commonly used microbial agent to control mosquitoes worldwide. 2. Using breeding house martins Delichon urbicum as a model species, we assessed the effect of Bti spraying on foraging rates and chick diet prior to and during 3 years of Bti spraying in the Camargue, France. Some 9051 feeding flights and 14 857 prey items were recorded in the early, mid and late nesting season at up to three control and three treated sites. Breeding parameters were assessed during 1 year at two control and two treated sites. 3. Intake of Nematocera (Diptera sub-order including midges and mosquitoes) and their predators (spiders and dragonflies) decreased significantly at treated sites, concurrently with increase of flying ant intake. Small prey ( 7·5 mm) at control sites, with lower foraging rates at treated sites. 4. Clutch size and fledgling survival were significantly lower at treated sites relative to control with respectively 2·3 vs. 3·2 chicks produced per nest. Breeding success was positively correlated with intake of Nematocera and their predators at the nest level. 5. No previous study has provided compelling evidence of Bti affecting vertebrate populations following the suppression of prey species. Indirect effects caused by repeated application of Bti through food web interactions warrant more attention. 6. Synthesis and applications. Bti is considered the most selective and least toxic agent currently available to control mosquitoes. Mosquito-control programmes should integrate non-biased awareness campaigns and mitigation measures balancing the social demands for mosquito reduction with the factors involved in mosquito proliferation and dispersion. Such measures could consist in improved wetland management; reduction in areas and periods of Bti spraying; consideration of alternatives to Bti spraying, such as mosquito traps; specific measures to reinforce animal populations affected by Bti; and suspension of mosquito control in environmentally sensitive areas where nature preservation is a priority.