Last Document Library from scales-project.net http://www.scales-project.net Fri, 17 Apr 2026 22:57:20 +0200 WebDesign LTD. FeedCreator http://www.scales-project.net/files/DOWNLOAD/Therville et al, 2017.pdf 31 January 2018

Navigating protected areas as social-ecological systems: integration pathways of French nature reserves

On a global scale, protected areas (PAs) are one of the main tools used for biodiversity conservation. However, accelerated biodiversity loss and lack of social acceptance of PAs call into question their ability to reach long-term biodiversity conservation objectives. To address this, conservation scientists and practitioners have moved from segregative to integrative models of PAs. When the segregative model sees PAs as human exclusion zones, the integrative model considers conservation and development projects and multiple partnerships with local stakeholders within and outside PAs. Given this paradigmatic evolution, a PA and its surrounding landscape are increasingly regarded as a single social-ecological system (SES). This development brings new challenges for conservationists: How should these complex and dynamic systems be managed, and how can their pathways be described and piloted? Using French nature reserves (NRs) as case studies, we propose a framework for analyzing the integration pathways of PAs within their social-ecological context. We identified the pathways of 10 NRs according to their degree of integration in the surrounding landscape (spatial), their management objectives (sectoral), and their governance systems (institutional). We analyzed these pathways using three metaphors associated with resilience thinking (adaptive cycle, adaptation, and transformation). We discussed how these 10 NRs have changed over time, revealing how practitioners anticipate future pathways and avoid undesirable states. Through an exploration of the totality of an SES’s spatial, sectoral, and institutional pathways, the framework we propose is a potential tool for identifying opportunities and constraints for long-term conservation actions.

]]> Wed, 31 Jan 2018 11:00:00 +0200 http://www.scales-project.net/files/DOWNLOAD/GuntonP?yry_2016_FunctEcol.pdf 03 February 2016

Scale-specific spatial density dependence in parasitoids: a multi-factor meta-analysis

Summary Within a landscape, the risk of an insect being attacked by a parasitoid varies with the local density of the host species. This relationship should be strongest when observed at medium extents and resolutions with respect to parasitoids’ foraging range, and turn negative at fine resolutions. The relationship is also hypothesized to depend on certain traits of the host and parasitoid taxa – for example being more positive for more specialized hosts or parasitoids and more negative for mobile hosts or gregarious parasitoids. Building on earlier literature reviews, it is now possible to investigate these hypotheses using meta-analysis. We performed a multi-factor meta-analysis on 151 analyses of parasitism rates with respect to host densities at specified scales, from 61 empirical studies published from 1988 to 2012. We explored how the correlation between host density and parasitism rate may be related to the explanatory variables already mentioned, plus parasitoid body length and various other characteristics of both hosts and parasitoids. Correlations (Pearson\'s r) between host density and parasitism rate ranged from –0·88 to 0·98 (mean 0·16, standard deviation 0·39). The correlation was more often negative where the host was exotic or in the orders Lepidoptera or Diptera, where the parasitoid was larger or exotic, or where the study was conducted at a finer grain size. Hymenoptera and Homoptera were the most likely host orders to reveal positive associations, with Coleoptera and Diptera intermediate. The fact that increased observational grain size had similar effects to decreased parasitoid body length could be taken as evidence that parasitoids’ foraging ranges increase with their body length. However, the hypothesis about scale-specific foraging was not supported by studies that compared multiple scales. We conclude that parasitism most commonly produces positive (compensatory) spatial density dependence, but ecological context is all-important. These findings should help improve the design and interpretation of field experiments on parasitism as well as their application to the modelling of population dynamics and the practice of biological control.

]]> Wed, 03 Feb 2016 11:00:00 +0200 http://www.scales-project.net/files/DOWNLOAD/SCHWEIGER_increasing range mismatching_interacting species_global change_Supplementary information.pdf 30 March 2015

SCHWEIGER_increasing range mismatching_interacting species_global change_Supplementary information

SCHWEIGER_increasing range mismatching_interacting species_global change_Supplementary information

]]> Mon, 30 Mar 2015 10:00:00 +0200 http://www.scales-project.net/files/DOWNLOAD/Sizling_et_al_2011_AmNat.pdf 30 March 2015

Between Geometry and Biology: The Problem of Universality of the Species-Area Relationship

The species-area relationship (SAR) is considered to be one of a few generalities in ecology, yet a universal model of its shape and slope has remained elusive. Recently, Harte et al. argued that the slope of the SAR for a given area is driven by a single parameter, the ratio between total number of individuals and number of species (i.e., the mean population size across species at a given scale). We provide a geometric interpretation of this dependence. At the same time, however, we show that this dependence cannot be universal across taxa: if it holds for a taxon composed from two subsets of species and also for one of its subsets, it cannot simultaneously hold for the other subset. Using three data sets, we show that the slope of the SAR considerably varies around the prediction. We estimate the limits of this variation by using geometric considerations, providing a theory based on species spatial turnover at different scales. We argue that the SAR cannot be strictly universal, but its slope at each particular scale varies within the constraints given by species’ spatial turnover at finer spatial scales, and this variation is biologically informative.

]]> Mon, 30 Mar 2015 10:00:00 +0200 http://www.scales-project.net/files/DOWNLOAD/BiolRev 2010.pdf 30 March 2015

A meta-analysis of dispersal in butterflies

Dispersal has recently gained much attention because of its crucial role in the conservation and evolution of species facing major environmental changes such as habitat loss and fragmentation, climate change, and their interactions. Butterflies have long been recognized as ideal model systems for the study of dispersal and a huge amount of data on their ability to disperse has been collected under various conditions. However, no single ‘best’ method seems to exist leading to the co-occurrence of various approaches to study butterfly mobility, and therefore a high heterogeneity among data on dispersal across this group. Accordingly, we here reviewed the knowledge accumulated on dispersal and mobility in butterflies, to detect general patterns. This meta-analysis specifically addressed two questions. Firstly, do the various methods provide a congruent picture of how dispersal ability is distributed across species? Secondly, is dispersal species-specific? Five sources of data were analysed: multisite mark-recapture experiments, genetic studies, experimental assessments, expert opinions, and transect surveys. We accounted for potential biases due to variation in genetic markers, sample sizes, spatial scales or the level of habitat fragmentation. We showed that the various dispersal estimates generally converged, and that the relative dispersal ability of species could reliably be predicted from their relative vagrancy (records of butterflies outside their normal habitat). Expert opinions gave much less reliable estimates of realized dispersal but instead reflected migration propensity of butterflies. Within-species comparisons showed that genetic estimates were relatively invariable, while other dispersal estimates were highly variable. This latter point questions dispersal as a species-specific, invariant trait.

]]> Mon, 30 Mar 2015 10:00:00 +0200 http://www.scales-project.net/files/DOWNLOAD/Travis et al. 2014_Oikos (early online).pdf 30 March 2015

Dispersal and species’ responses to climate change

Dispersal is fundamental in determining biodiversity responses to rapid climate change, but recently acquired ecological and evolutionary knowledge is seldom accounted for in either predictive methods or conservation planning. We emphasise the accumulating evidence for direct and indirect impacts of climate change on dispersal. Additionally, evolutionary theory predicts increases in dispersal at expanding range margins, and this has been observed in a number of species. This multitude of ecological and evolutionary processes is likely to lead to complex responses of dispersal to climate change. As a result, improvement of models of species’ range changes will require greater realism in the representation of dispersal. Placing dispersal at the heart of our thinking will facilitate development of conservation strategies that are resilient to climate change, including landscape management and assisted colonisation. Synthesis This article seeks synthesis across the fields of dispersal ecology and evolution, species distribution modelling and conservation biology. Increasing effort focuses on understanding how dispersal influences species\' responses to climate change. Importantly, though perhaps not broadly widely-recognised, species\' dispersal characteristics are themselves likely to alter during rapid climate change. We compile evidence for direct and indirect influences that climate change may have on dispersal, some ecological and others evolutionary. We emphasise the need for predictive modelling to account for this dispersal realism and highlight the need for conservation to make better use of our existing knowledge related to dispersal.

]]> Mon, 30 Mar 2015 10:00:00 +0200 http://www.scales-project.net/files/DOWNLOAD/Tsianou et al., 2013; Biological Conservation.pdf 30 March 2015

Identifying the criteria underlying the political decision for the prioritization of the Greek Natura 2000 conservation network

The Natura 2000 network represents the largest conservation network in the world that has been established under common directives adopted by all member states of European Union. The Greek state, in the context of implementing the directives and managing the Natura 2000 sites, selected only a part of the network (83 sites) to be under a specific management scheme, forming a “sub-network” of managed sites. To assess the potential decision-making criteria and principles which underlie the selection process of this sub-network, we applied a multi-criteria approach including ecological, socioeconomic and management history criteria. We found that the sub-network of managed sites performed better than random for some criteria and worse than random for other criteria. Our results demonstrate that the sub-network was close to optimal for management history related criteria and better than random for ecological factors. On the other hand, human activities, population density and land value were undervalued in the prioritization process. Several sites, however, consistently scored high for all criteria and approximately half of them are included in the sub-network of managed sites. The prioritization of conservation efforts on these sites is important in the post-financial crisis era when public funding for conservation is rapidly decreasing and conservation administration is being gradually dismantled. Our study emphasizes the intricacy involved in conservation planning by highlighting that the selection of the managed sites of the Greek Natura 2000 network was primarily based on scientific reasoning and political motivations whereas a more integrative approach, such as considering socioeconomic factors, appears to be absent from the process.

]]> Mon, 30 Mar 2015 10:00:00 +0200 http://www.scales-project.net/files/DOWNLOAD/Vergnes_etal_BiolCons_2012.pdf 30 March 2015

Green corridors in urban landscapes affect the arthropod communities of domestic gardens

Ecological corridors are landscape elements that prevent the negative effects of fragmentation. However, their effectiveness has never been clearly validated in urban landscapes. We analysed the role of green corridors in an urban context by comparing metacommunities of arthropods in (i) woodlots considered as sources of species, (ii) woody corridors and domestic gardens that are (iii) connected (CG) or (iv) disconnected to corridors (DG) and taking into account the connectivity of the matrix. We trapped 3 taxa of arthropods – spiders, carabids and staphylinids – because they are sensitive to fragmentation but with different dispersal capabilities. We analysed their species richness, abundance and taxonomic and functional composition. For the 3 taxa, the taxonomic and functional compositions of communities in CG were closer to those of the corridor and the source than those of DG. Woodland species were associated with source, corridor and CG. A lower abundance in DG was revealed for staphylinids and spiders. Lower species richness in DG was observed for staphylinids. The differences between taxa could be explained by the dispersal capabilities of the species and by their various responses to landscape structures. For carabids, processes at a wider scale could be responsible for their rarity in sources and, consequently, in gardens. For spiders, the colonisation from other sources could explain the high species richness found in disconnected gardens. Our results suggest that the role of corridors is crucial for enhancing biodiversity in green spaces such as domestic gardens. Our results clarify the effectiveness of corridors in urban landscapes and have direct implications for the ecological management of cities.

]]> Mon, 30 Mar 2015 10:00:00 +0200 http://www.scales-project.net/files/DOWNLOAD/2012-YuEtAl-STAR-BME-GIS-Proc.pdf 30 March 2015

Advanced Space-Time Predictive Analysis With STAR-BME

Stochastic analysis and prediction is an important component of space-time data processing for a broad spectrum of Geographic Information Systems scientists and end users. For this task, a variety of numerical tools are available that are based on established statistical techniques. We present an original software tool that implements stochastic data analysis and prediction based on the Bayesian Maximum Entropy methodology, which has attractive advanced analytical features and has been known to address shortcomings of common mainstream techniques. The proposed tool contains a library of Bayesian Maximum Entropy analytical functions, and is available in the form of a plugin for the Quantum GIS open source Geographic Information System software

]]> Mon, 30 Mar 2015 10:00:00 +0200 http://www.scales-project.net/files/DOWNLOAD/02bfe50ed9ae6d3997000000.pdf 30 March 2015

The formation of species pools: historical habitat abundance affects current local diversity

Aim  Explanations of biogeographic diversity patterns have emphasized the role of large-scale processes that determine species pools, whereas explanations of local patterns have not. We address the hypothesis that local diversity patterns are also primarily dependent on the size of the available species pools, which are expected to be large when the particular habitat type has been evolutionary more abundant, or in unproductive habitats due to shorter generation time and hence higher diversification rates. Location  The Canary Islands. Methods  We determined the geographic distribution and habitat requirements of all native vascular plant species in the Canary Islands. Species pools for each habitat type on particular islands were further split into two categories according to origin: either originating due to local diversification or due to natural immigration. The dependence of historical diversification and diversification rate on habitat type, area, age, altitude and distance to the mainland was tested with general linear mixed models weighed according to the Akaike information criterion. Results  The largest portion of the local variation in plant species diversity was attributed to the historic (pre-human) habitat area, although island age was also important. The diversification rate was higher in unproductive habitats of coastal scrub and summit vegetation. Main conclusion  Our study supports the species pool hypothesis, demonstrating that natural local patterns of species diversity in different habitats mirror the abundance of those particular habitats in evolutionary history. It also supports the community-level birth rate hypothesis, claiming that stressful conditions result in higher diversification rates. We conclude that much of the observed local variation in plant diversity can be attributed to the differing sizes of species pools evolved under particular habitat conditions, and that historic parameters are far more important determinants of local diversity than suggested by ecological theory.

]]> Mon, 30 Mar 2015 10:00:00 +0200 http://www.scales-project.net/files/DOWNLOAD/09e4150aa17346e8ed000000.pdf 30 March 2015

Landscape variables impact the structure and composition of butterfly assemblages along an urbanization gradient

How urbanization affects the distribution patterns of butterflies is still poorly known. Here we investigated the structure and composition of butterfly assemblages along an urbanization gradient within the most urbanized and densely populated region in France (Île-de-France). Using a method issued from artificial neural networks, i.e. self-organizing maps (SOMs), we showed the existence of four typical assemblages ranging from urban-tolerant species to urban-avoider species. We identified indicator species of these assemblages: the peacock butterfly (Inachis io) in urbanized areas, the swallowtail (Papilio machaon) in sites with intermediate human pressure, or the meadow brown (Maniola jurtina), the small heath (Coenonympha pamphilus) and the gatekeeper (Pyronia tithonus) in meadows around Paris. A discriminant analysis showed that the four assemblages were mainly segregated by landscape elements, both by structural variables (habitat type, proportion of rural areas and artificial urban areas, patch surface) and functional variables (distance to the nearest wood, artificial area and park). Artificial neural networks and SOMs coupled stepwise discriminant analysis proved to be promising tools that should be added to the toolbox of community and spatial ecologists.

]]> Mon, 30 Mar 2015 10:00:00 +0200 http://www.scales-project.net/files/DOWNLOAD/acv12030.pdf 30 March 2015

Assessing the Natura 2000 network with a common breeding birds survey

Natura 2000 (N2000) is a network of European sites focused on the conservation of specific species and habitats. Despite the known importance of common biodiversity in ecosystem functioning, common species are currently not explicitly targeted by conservation initiatives in France. In this study, we investigated whether the N2000 network contributes to the protection of common breeding bird species. In particular, we focused on species abundance and species specialization, community specialization and community trophic levels. We also determined the effects of N2000 on temporal trends of specialist and generalist bird groups. We studied 100 species in 1461 plots monitored by the French Breeding Bird Survey (BBS) between 2001 and 2010. We found that species abundance increased for 54 species with the proportion of the plot covered by N2000 areas in the plot. The bird species with the abundances that were most influenced by proportion of the plot covered by N2000 areas were predominantly habitat specialists. Bird communities inside N2000 sites were more specialized and exhibited higher trophic indices than communities outside N2000 sites. We found no differences in the temporal trends of farmland and woodland birds inside and outside N2000 sites, but the temporal trend of generalist species was positive outside N2000 sites and stable inside. We concluded that N2000 sites showed greater abundance of a majority of common bird species but that the network was established too recently to assess its influence on population trends. The French BBS has proved to be an efficient tool in assessing protected area networks.

]]> Mon, 30 Mar 2015 10:00:00 +0200 http://www.scales-project.net/files/DOWNLOAD/Pinke&Gunton_14_preprint.pdf 30 March 2015

Refining rare weed trait syndromes along arable intensification gradients

Question How does the conservation (rarity) value of arable weed communities differ along intensification gradients? Which functional traits best distinguish the weed communities of more and less extensively managed fields? Can the same traits predict the rarity of individual weed species? Location Hungary. Methods Using relevé data from 60 cereal and 70 stubble fields, together with weed trait data, we characterized community responses to arable intensification using functional trait analyses based on trait-convergence and trait-divergence assembly patterns. We also examined how well the broad-scale rarity status of species predicts their occurrence along intensification gradients, and how it maps onto our functional classifications describing intensification responses. Results The response of weeds to intensification in cereal fields was best described by a functional classification based on species\' flowering duration, maximum height and seed weight: weeds of extensively managed fields have short flowering seasons (2–5 mo) and particularly large or small seeds. The highest proportions of rare species also happen to be found in these groups. The rarest weeds among these species tend to be late-winter and early-summer annuals, while the rare species of stubble fields tend to be broad-leaved with low nitrogen requirements, small seeds and short height. Stubble fields showed a decline in weed cover with increasing application of fertilizer and distance from the field edge, but we could detect no strong associations of management factors with trait composition, perhaps because the intensification gradient across these fields was shorter. Conclusions Many rare Hungarian weeds are associated with traditional extensive farming practices. They are particularly characterized by short, midsummer flowering periods and by preference for low nitrogen levels, but a range of trait syndromes must be considered to understand their ecology and conservation. Analyses based on trait-divergence patterns, rather than trait-convergence patterns, provide better insights into the functional composition of weed communities, emphasizing the importance of disruptive filters in weed community assembly and the need for improved methods to detect such effects.

]]> Mon, 30 Mar 2015 10:00:00 +0200 http://www.scales-project.net/files/DOWNLOAD/primmer et al SCALES_concepts__ submitted.pdf 30 March 2015

An Approach to Analysing Scale-Sensitivity and Scale-Effectiveness of Governance in Biodiversity Conservation

The governance of global environmental challenges has been conceptualized comprehensively and often accurately, but it is often difficult to design institutions that provide incentives for conservation and, at the same time, control for reaching the targets across scales, utilizing available knowledge and satisfying multiple interests. This chapter analyses four governance mechanisms in biodiversity conservation: (i) command and control; (ii) planning and management: (iii) market-oriented mechanisms and economic instruments; and (iv) collaborative and participatory. It discusses the ways in which these mechanisms emphasize control and adaptiveness. The analysis utilizes governance literature and secondary material on illustrative biodiversity governance examples in different areas in Europe. The chapter draws conclusions for scale-sensitive and scale-effective analysis and policy.

]]> Mon, 30 Mar 2015 10:00:00 +0200 http://www.scales-project.net/files/DOWNLOAD/Schatz et al 2014 JNC_1.pdf 30 March 2015

A decision tool for listing species for protection on different geographic scales and administrative levels

An important task in conservation biology is to assess the spatial scale pertinent for species protection since some species may require protection throughout their distribution, others in only part of their range. Once this is done, species can be correctly identified for listing at different administrative levels (e.g. continental, national, and local). Here, we propose an objective method to list taxa at nested administrative levels based on three criteria (responsibility, rarity and vulnerability). We tested the method using quantitative data on the distribution, abundance and decline of orchids in France. The proposed method enables increased protection status in regions where species’ abundance and diversity are higher, gives priority to species for which an individual administrative unit has high responsibility and allows objective integration of species decline at different administrative levels. The method also enables the integration of locally rare species at their distribution limits and avoids repetition of species listing across second-level administrative units. The use of an objective method such as this could contribute to a standardised system of priority setting that integrates the geographic scale of rarity in relation to different administrative levels for protection.

]]> Mon, 30 Mar 2015 10:00:00 +0200 http://www.scales-project.net/files/DOWNLOAD/Vergnes_etal_BiolCons_2012_1.pdf 30 March 2015

Green corridors in urban landscapes affect the arthropod communities of domestic gardens

Ecological corridors are landscape elements that prevent the negative effects of fragmentation. However, their effectiveness has never been clearly validated in urban landscapes. We analysed the role of green corridors in an urban context by comparing metacommunities of arthropods in (i) woodlots considered as sources of species, (ii) woody corridors and domestic gardens that are (iii) connected (CG) or (iv) disconnected to corridors (DG) and taking into account the connectivity of the matrix. We trapped 3 taxa of arthropods – spiders, carabids and staphylinids – because they are sensitive to fragmentation but with different dispersal capabilities. We analysed their species richness, abundance and taxonomic and functional composition. For the 3 taxa, the taxonomic and functional compositions of communities in CG were closer to those of the corridor and the source than those of DG. Woodland species were associated with source, corridor and CG. A lower abundance in DG was revealed for staphylinids and spiders. Lower species richness in DG was observed for staphylinids. The differences between taxa could be explained by the dispersal capabilities of the species and by their various responses to landscape structures. For carabids, processes at a wider scale could be responsible for their rarity in sources and, consequently, in gardens. For spiders, the colonisation from other sources could explain the high species richness found in disconnected gardens. Our results suggest that the role of corridors is crucial for enhancing biodiversity in green spaces such as domestic gardens. Our results clarify the effectiveness of corridors in urban landscapes and have direct implications for the ecological management of cities.

]]> Mon, 30 Mar 2015 10:00:00 +0200 http://www.scales-project.net/files/DOWNLOAD/Mimet_mee_2013.pdf 21 March 2015

Assessing functional connectivity: a landscape approach for handling multiple ecological requirements

1. The improvement of tools for protecting biodiversity requires integrating habitat connectivity to build efficient ecological networks that facilitate the movement of species under pressure from global change. Several methodological and scientific challenges are faced in constructing such networks. First, ecological networks need to incorporate habitat connectivity for species with different ecological requirements. Secondly, the networks should be based on functional connectivity rather than on structural connectivity alone. Thirdly, connectivity needs to be treated as a continuous variable. We propose a non-oriented approach of landscape description to identify favourable areas and measure functional connectivity for multi-specific applications, using three groups of common bird species (farmland specialists, forest specialists and generalists) as indicators of biodiversity. In the highly anthropized region of Seine-et-Marne, we defined 20 landscape types based on composition and configuration. We used statistical modelling to obtain a value of favourability for each landscape type for each bird group. We then mapped landscape favourability, for the three groups in 1982 and 2003 to identify favourable entities (adjacent favourable landscape units) and determine connectivity. We then examined temporal changes in the favourable areas and their connectivity and determined the sensitivity of the favourable landscape types to land cover change. Composition and configuration both influenced landscape favourability. Some landscape types were favourable for several groups of species and could potentially serve as junction landscapes in ecological networks that accommodate a variety of ecological requirements. Increasing urbanization and fragmentation between 1982 and 2003 resulted in a decrease in favourable landscape units, as well as consequent decreases in favourable areas and connectivity, for the three species groups. Connectivity loss was greatest for farmland and generalist species, as it was already high for forest species in 1982. Such a non-oriented landscape description could be used to delineate multi-specific ecological networks at regional and national scales and could be further developed to study the connectivity of communities. The maps of favourability produced here could also be used in combination with other methods, such as graphs or circuits, to detect ecological corridors and stepping stones to habitat connectivity.

]]> Sat, 21 Mar 2015 11:00:00 +0200 http://www.scales-project.net/files/DOWNLOAD/Sylvain Moulherata et al. 2014.pdf 21 March 2015

How far can a tortoise walk in open habitat before overheating? Implications for conservation

Terrestrial chelonians are threatened worldwide by habitat destruction and illegal harvesting. Tortoises are slow moving animals susceptible to dehydration and overheating during movements in open habitats. Many species inhabit arid steppes where the availability of thermally buffered refuges (e.g. burrows) is a limiting factor. Determining the maximal distance between refuges that individuals can safely traverse during the active season is thus essential. We examined the relationship between body temperature variations and movement patterns in adult Testudo graeca in the arid steppes of Morocco. Using physical and mathematical models, our results suggest that during the active season adults cannot travel more than 1 km without serious risk of overheating. However, radio-tracking suggests that free-ranging individuals are behaviourally limited to 0.5 km trips between refuges. Overall, maintaining a distance less than 0.5 km between refuges (e.g. through bush planting) is essential to limit fragmentation and to retain healthy populations. This restoration would also benefit to many other species that depend on bush-refuges.

]]> Sat, 21 Mar 2015 11:00:00 +0200 http://www.scales-project.net/files/DOWNLOAD/Nascimbene_etal_2012_freepdf.pdf 21 March 2015

Drivers of lichen species richness at multiple spatial scales in temperate forests

Background: Few studies analysing lichen diversity have simultaneously considered interactions among drivers that operate at different spatial and temporal scales. Aims: The aims of this study were to evaluate the relative importance of host tree, and local, landscape and historical factors in explaining lichen diversity in managed temperate forests, and to test the potential interactions among factors acting at different spatial scales. Methods: Thirty-five stands were selected in the Őrség region of western Hungary. Linear models and multi-model inference within an information-theory framework were used to evaluate the role of different variables on lichen species richness. Results: Drivers at multiple spatial scales contributed to shaping lichen species richness both at the tree and plot levels. Tree-level species richness was related to both tree- and plot-level factors. With increasing relative diffuse light lichen species richness increased; this effect was stronger on the higher than on the lower part of the trunks. At the plot scale, species richness was affected by local drivers. Landscape and historical factors had no, or only a marginal, effect. Conclusions: Lichen conservation in temperate managed forests could be improved if the complex interactions among host tree quality and availability, micro-climatic conditions, and management were taken into consideration.

]]> Sat, 21 Mar 2015 11:00:00 +0200 http://www.scales-project.net/files/DOWNLOAD/D27_Nowicki_et_al_2009_Abstract.pdf 21 March 2015

Relative importance of density-dependent regulation and environmental stochasticity for butterfly population dynamics

The relative contribution of density-dependent regulation and environmental stochasticity to the temporal dynamics of animal populations is one of the central issues of ecology. In insects, the primary role of the latter factor, typically represented by weather patterns, is widely accepted. We have evaluated the impact of density dependence as well as density-independent factors, including weather and mowing regime, on annual fluctuations of butterfly populations. As model species, we used Maculinea alcon and M. teleius living in sympatry and, consequently, we also analysed the effect of their potential competition. Density dependence alone explained 62 and 42% of the variation in the year-to-year trends of M. alcon and M. teleius, respectively. The cumulative Akaike weight of models with density dependence, which can be interpreted as the probability that this factor should be contained in the most appropriate population dynamics model, exceeded 0.97 for both species. In contrast, the impacts of inter-specific competition, mowing regime and weather were much weaker, with their cumulative weights being in the range of 0.08–0.21; in addition, each of these factors explained only 2–5% of additional variation in Maculinea population trends. Our results provide strong evidence for density-dependent regulation in Maculinea, while the influence of environmental stochasticity is rather minor. In the light of several recent studies on other butterflies that detected significant density-dependent effects, it would appear that density-dependent regulation may be more widespread in this group than previously thought, while the role of environmental stochasticity has probably been overestimated. We suggest that this misconception is the result of deficiencies in the design of most butterfly population studies in the past, including (1) a strong focus on adults and a neglect of the larval stage in which density-dependent effects are most likely to occur; (2) an almost exclusive reliance on transect count results that may confound the impact of environmental stochasticity on butterfly numbers with its impact on adult longevity.

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