1,721,014 research outputs found
A wolf habitat suitability prediction study in Valais (Switzerland)
No full textIn recent years, the European wolf (Canis lupus) population has expanded its southern range from the Italian Peninsula to the Maritime Alps (Italy and France) and to Piemonte (Italy); establishing small sub-populations. Hence re-colonisation of the Swiss Alps is now likely to occur. In 1995-1996 the wolf reached the southern part of Switzerland (Canton of Valais) from where he got extinct 150 years ago. Actual conflicts of interests between livestock breeders, local political authorities and nature conservation parties, as well as federal authorities defending the protected status of wolf, require serious management investigations. In order to check wolf habitat suitability of an alpine landscape, like the Valais, subjected to dynamic landscape-ecology processes since the extinction of wolf, we present herein an application of a predictive wolf habitat model, using a stochastic model involving logistic regression. As no data were available in the Canton of Valais, the regression coefficients for the retained variables such as urban area, population density, arable land, minimal altitude, northwest exposure and wild ungulate diversity index, were derived from data collected in the northern Apennine (Northern Italy), where habitat variables were related to data of wolf presence. The selection of the parameters for the Canton of Valais has been performed in respect of their predictive power, as well as their availability and geo-morphological importance for the alpine landscape under consideration. Using the geographic information system (GIS), the simulation pointed out that 19% (1142 km2) of the total grid surface (5821 km2) are suitable for wolf presence. Moreover, it reveals that especially areas at lower altitudes (minimum altitude 1800-2000 m a.s.l.), due to lack of prey and severe geo-morphological conditions, present a reduced habitat suitability. The geomorphological and demographic situation of the alpine area lead to a wolf habitat of a partially fragmented and linear aspect, affecting overall habitat suitability. The strengths of the application is not only the visualisation of the present habitat quality of an alpine landscape recolonised by wolves, but also that it allows to make investigations in order to manage the different conflicts of interest. RI Massolo, Alessandro/I-3437-201
Système d'indicateurs environnementaux pour évaluer les impacts principaux de l'exploitation du pétrole dans une région pilote en Colombie
No full textGECO
Benthic macroinvertebrates and logging activities : a case study in a lowland tropical forest in East Kalimantan (Borneo, Indonesia)
No full textAt the beginning of the 21 century, the conservation of biodiversity and the sustainable use of natural resources remains a matter of concern. Within this framework, the aim of this research was to study the effects of logging activities on ecological water quality indicators in a tropical forest. The study was undertaken at both local (species/habitat) and landscape (watershed) scales. The study took place on Borneo Island, in East Kalimantan province (Indonesia), in a state-owned timber concession, on an area of 85 km2. In order to study the impact of logging activities at landscape scale, five satellites images (1991, 1997, 1999, 2000 and 2001) were examined. The ecological water quality was evaluate by a biological and a habitat assessment, which were performed at each stream reach. The biological assessment constituted in collected benthic macroinvertebrates. This protocol was conducted at 23 sampling sites on headwater streams in order to compare the impacts of logging in logged area versus unlogged area. Logged area were grouped by the time interval after logging. We examined several groups: recently logged (during logging and until 6 months after logging), 1 to 3 years after logging and, 4 to 5 years after logging and relogged for a second time. Two field seasons occurred in June-August 2000 and April-May 2001. During this eight months time interval, most of the timber concession was relogged for a second time, as a result of the decentralisation process at government level. The research took four years and the following main results have been obtained. Logging activities at landscape scale were quantified by the total length of logging roads. This underlined the intensification of the logging activities from one satellite image to the other over the time (from 1991 to 2001). Vegetation classification and vegetation index (NDVI) could not be used to assessing the impact of logging activities on forest quality because of the homogeneous forest cover in the study site (no visible patches). Benthic macroinvertebrates and environmental variables were considered an ideal tool to assess the ecological water quality in the study site. Macroinvertebrates richness was high with 115 taxa mainly identified at family and sub-family level (genera for Ephemeroptera), but abundance was low (mean density of 770 individuals per square meter, ranging from 86 to 2130). Multivariate analysis highlighted that the size of the streams and the impact of logging activities played an important role in ordinating the samples. A co-inertia analysis demonstrated that benthic macroinvertebrates and environmental variables were found to be strongly related to each others. The main results indicated that macroinvertebrate density, richness, diversity, composition and functional feeding organisation responded to logging activities. During and six months after logging, macroinvertebrate density was higher and diversity indices were lower compared to the reference samples (unlogged situation). One to three years after logging were found to be the most disturbed situation, indicated, among other things, by an even lower diversity indices. Environmental variables responded to logging activities by: an increase in canopy opening, water temperature, amount in fine sediment and flow velocity and by a decrease in Fine Particulate Organic Matter (FPOM). The stream ecosystems seemed to recover 4 to 5 years after logging in absence of ongoing activities, density and diversity seemed similar but benthic macroinvertebrate composition is different compared to reference unlogged situation. Among the 115 taxa identified during the study, several were indicator taxa, meaning that they characterised the impact of logging activities at a given time. Indicator taxa were grouped in five categories: "open canopy" taxa (Platybaetis, Lepidoptera, Hydropsychinae); "sensitive" taxa (e.g. Caenodes, Limonidae, Potamanthus, Perlidae, Philopotamidae); "pulse" taxa (e.g. Psephenidae, Jubabaetis, Platybaetis, Megaloptera, Glossossomatidae) ; "recovery" taxa (e.g. Labiobaetis, Helicopsychidae, Platystictidae) and "adaptive" taxa (Diplectroninae, Simuliidae, Isca). A Tropical Stream Concept was proposed to take into account the paucity of shredders collected in the headwater catchment streams. The higher decomposition rate and terrestrial shredders provides the Fine Particulate Organic Matter as direct input from the washing out of the catchment during rainy events. In summary, macroinvertebrates can be considered excellent indicators, which were successfully used in this tropical environment for both objectives: they assessed biodiversity as an element of forest sustainability and they assessed disturbances due to logging activities, with the advantage to be indicative of recent and past events. Further research is proposed to test the identified indicator taxa to other regions in Borneo, to valid them and to prepare a simplified key to be used by local institutions as a tool for monitoring ecological water quality.GECO
Bases méthodologiques de la participation lors de projets ayant des impacts sur le paysage : cas d'application: la plaine du Rhône valaisanne
No full textRecently, participation emerged as an appropriate tool to enhance natural resource management. Despite official recognition, there is no consensus on the practical meaning of participation. In this work, we consider the participation as a process through which stakeholders influence and share control over development initiatives and the decision and resources affecting them. The aim of this research is to answer to the participation's issues : who should participate? when? and how? The main contribution of this reserach work is to propose a methodology that allows to introduce the participation for large projects having impacts on the landscape. The result of this methodology is a system of participation. This system is composed of elements (project, stakeholders, techniques and levels of participation) and processes (identification, characterisation and structuration of the stakeholders, identification of the participation level, choice of the participation techniques, application and evaluation of the participation) in interaction. This system of participation is general and can be used for others projects. Howewer, the chronological order of the processes is iterative and is project specific. For each of the process used in the participation system, techniques were adapted, deveopped and tested. Stakeholders identification followed the adapatation of the Mason and Mitroff technique. Stakeholders structuration was made using cluster analysis. Identification of the level of participation followed the modifications of the Daniels et al and Vroom models. Relevent identification and assessment of participation techniques were made with the help of tables. All these thechniques yield results readily and pratically usable. The way stakeholders perceive the landscape and its dynamics are also studied in this research. This study allows to analyze the type and the effects of the information presented on the participative process and on the stakeholders. Based on our results, we advise to present landscape dynamics in a participative context. We recommand the use of simple landscape metrics such as the area doubled with the spatialization of the transition matrix. The stakeholders landscape preference allows to identify criteria such as the attitude towards the changes that would help in the elaboration of the future project. The originalities of this study can be found at various levels. In a general way, we can list the globality of the proposed methodology, the overlap of the social and technical sciences and the application of the methodology to the third Rhone correction project. In a more specific way, we can mention technical developments such as the application of original experiments concerning the identification of stakeholders landscape preferences. The system of participation proposed provides a conceptual framework that can be applied to others participative projects such as agenda 21 or the development of any projects having impacts on the landscape.GECO
Interaction between landscape structure and regional climatea numerical experiment over central Spain
No full textGECO
Dead wood in managed forests: how much and how much is enough? : development of a snag-quantification method by remote sensing & GIS and snag targets based on Three-toed woodpeckers' habitat requirements
No full textThe aims of this research were twofold: to develop an efficient method for the quantification of large spruce snags (standing dying and dead trees), and to establish snag target values for sustainable forest management. We answer the two basic questions: how much dead wood is currently available in managed forests? And how much dead wood is enough for biodiversity conservation? It is widely accepted that modern forest management has to be sustainable. One generally recognised criterion of sustainability is the maintenance of biodiversity. Since this concept encompasses a large range of scales and features (landscapes, ecosystems, species and genes; components, processes, functions, etc.), biodiversity indicators have been identified for measurement and monitoring purposes. "Dead wood" has been recognised as a key indicator for biodiversity in forest ecosystems. Verifying and assessing progress towards biodiversity maintenance or restoration hence requires the measurement of different kinds of dead wood. Yet cost-efficient and rapid methods are still lacking. That is why we developed in this thesis an efficient method for the quantification of large spruce snags. Being based on infrared Aerial Photos and a Geographic Information System (GIS), it is called the AP-GIS-method. It enables mapping of snags and calculation of the spatial snag-density, i.e. the number of snags per hectare, and can be used to answer the question: How much dead wood is in managed forests? Beside techniques to assess dead-wood quantities, forest managers need quantitative target values, i.e. guidelines in order to know how much dead wood should be maintained in managed forests for biodiversity conservation. Natural forests may be used as reference systems to define such targets. However, since dead-wood amounts in natural forests may be extremely high, up to 30% of dead trunks, the retention of such amounts in managed forests would hardly be compatible with economic objectives. Another possibility for defining guidelines is the translation of the habitat requirements of deadwood- dependent species into management targets. The Three-toed woodpecker Picoides tridactylus has previously been recognised as a potential indicator species of features characteristic for forests with natural dynamics (especially old-growth). Although ecological studies had demonstrated its need of dying and dead trees for foraging, nesting and drumming, the required density of such trees has never been quantified. In this thesis, we analysed the dependence on dead wood for both European subspecies, the Alpine Picoides tridactylus alpinus and the northern P. tr. tridactylus. The study was conducted in sub-Alpine spruce forests in Switzerland and boreal forests in central Sweden. In both countries, we found a significant non-linear response of the probability of woodpecker presence to different amounts of dead trees, and identified critical ecological thresholds for the local presence of this species. Clearly, the Three-toed woodpecker depends on relatively high amounts of dying and dead trees. In Switzerland, the road network density negatively affected the presence of this woodpecker species, since a high road density facilitates forest management intensification and the removal of diseased and dead trees. Based on our results, and since several other links with biodiversity have previously been demonstrated, we suggest that Three-toed woodpeckers be considered indicators of dead wood and habitat quality. This species has therefore been used in this thesis to find an answer to the question: How much dead wood is enough in managed forests? In order to ascertain dead-tree targets, we developed a bioenergetic model for Threetoed woodpeckers, enabling estimation of snag amounts required by this species to satisfy its energy needs. By comparing modelling results with the previously identified critical dead-wood thresholds, we were able to derive reliable targets, since both approaches resulted in similar critical values. We recommend, for both boreal and sub-Alpine spruce forests, aiming for 5% of the standing tree basal area, or volume to be dead. Such snag-retention levels, to be applied over an area of about 100 ha, correspond in sub-Alpine forests to a basal area of ≥ 1.6 m2 ha-1, or a volume of ≥ 18 m3 ha-1, or a minimum of 14 snags with a diameter ≥ 21 cm per hectare. Considered as a pragmatic way to stimulate forest managers' interest in dead wood maintenance or restoration, we analysed the potential usefulness of Three-toed woodpeckers as natural agents against bark beetles. By defining three scenarios for different levels of woodpecker effectiveness, we compared the numbers of bark beetles consumed with those caught in pheromone traps used in forestry. We demonstrate that woodpeckers catch 2-19 times more bark beetles than traps do. This result is true for both cases, when one woodpecker is compared with one trap, and when the whole Swiss woodpecker population is compared to all traps installed in Swiss forests.GECO
Dynamique du paysage rural de la partie nord-ouest de la Suisse : une analyse pour comprendre la variation des populations du lièvre brun (Lepus europaeus)
No full textSince the 1950s, the population of the Brown hare (Lepus europaeus) has dramatically decreased in Switzerland as well as in other European countries. According to the Swiss Ornithological Institute of Sempach, this animal is an adequate indicator of the state of the landscape. Its decrease is probably due to intensification of agricultural practices, extension of urbanism and development of transport networks (Pfister et al., 2002). Today, the Brown hare is on the Swiss Red list of species that must be protected. This thesis presents an analysis of the landscape dynamics of the North-Western part of Switzerland, from the 1950s to the 1990s, through an historical analysis of the state of the landscape as it is perceived by the hare. In particular, we identify the factors of the landscape that are relevant for this animal, determine their trend of evolution, and finally postulate hypotheses for the evolution over the next years and their consequences for the hare populations. For each decade, 936 communes are described, using 40 variables related to agricultural practices, land-use, morphology, urbanisation, climate and geography. This database is called "Landscape". These data, mainly extracted from communal statistics, were found to be adequate to describe the evolution of the composition of the landscape at a large scale. We studied the content, the quality and the organisation of this database "Landscape" with the help of descriptive statistical methods (data distribution, histograms and boxplots at each decade, dynamics of the statistical characteristic values) and using principal components analysis (PCA). The latter reveals two groups of communes: urban (belonging to an agglomeration) and rural. On average, it also shows a very definite evolution of the urban character of both groups, from the 1950s to the 1990s. The three first components of the PCA explain only 45% of the variance. Therefore, we decided not to simplify the database by replacing our variables by these agglomerated variables, as the loss of information would be important. Among the 40 variables, 16 key-variables for the hare were identified. For this, an "Index of abundance of hares" was calculated for a sub-set of 125 communes, defined as the mean number of hares hunted per total communal area between 1980 and 1985. The link between this index and the 40 variables, describing the state of 125 communes in the 1980s, was analysed with the use of correlation, linear multiple regression, the method Pegase (a multivariate hierarchical divisive procedure, based on information theory (Phipps, 1981)), and additional information from the Swiss Ornithological Institute of Sempach. These methods were found to be complementary and their use enables us to take into account several perspectives. It would be interesting to go further by calculating this index for a larger number of communes in order to optimise the use of Pegase. The main trends of evolution of these key-variables, observed on the 936 communes, between the 1950s and the 1990s, are: 1. Decrease in the fraction of agricultural area; 2. Intensification of agricultural practices, increase in the mean ownership unit area (mean parcel size), changes of the type of agriculture; 3. Urbanisation and increased private car use; 4. Slight increase in rainfall. Two scenarios of evolution of the landscape for the next years are defined. Presuming that the identified trends will continue (Scenario A), the situation of the population of the hare will rapidly become critical: 1. The slow decrease in agricultural area will induce a pressure on the potential habitat of the hare; 2. The strong increase in areas of road/rail will reduce the habitat of the hare and most of all induce a fragmentation of the landscape, as well as barriers that are often impassable for the hare; 3. The extremely rapid increase in the number of cars will lead to an increase in road kill; 4. The increase in mechanisation in the agricultural practices, shown by the increase in the mean parcel size, the decrease in the working force and the slight increase in the number of tractors, are three reasons of important disturbance of the hare's habitat. In addition, the increasing rainfall, even if small, makes it probably more difficult for the animal, as it doesn't appreciate wet soils. On the other hand, in case the areas with corn stay relatively stable, and the grants for land improvement keep on decreasing, gradually "replaced" by grants encouraging extensive agricultural practices like direct grants for ecological compensation measure, the situation of the hare could stop getting worse. This scenario corresponds to a management of the territory that would not take into account new constraints and needs appearing with time. In order to take this into account, a second scenario (B) is defined, which is less extreme. It is based on trends for the future discussed by the Federal Agency for Agriculture, in the proposal for a modification of the law in the canton Vaud on country planning and buildings, and in the monitoring of Swiss statistics of the country. Both scenarios are rather pessimistic: for more than half of the key-variables integrated in both scenarios, the evolution probably leads to a negative situation for the hare. As this species is a good indicator of the quality of the landscape (Pfister et al., 2002), we recommend to take into account the needs for this species in the future management of the territory. According to our results, it would be important for the hare population to remain stable or even increase: 1. To encourage extensive agricultural practices; 2. To slow down, or better stop, the extension of urban areas and road/rail networks; 3. To reduce private car use. As these two last recommendations seem quite unrealisable in the near future, we propose to extend the network of favourable structures for the hare: hedges, fallow land and other areas close to natural state. At the same time, a plan of observation has to be developed, in order to control the results of these measures. These measures would enable sustainable growth of hare population, and, at the same time, sustainable management of resources and our patrimony
Process-based, spatially-explicit modelling of riparian forest dynamics in Central Europe : tool for decision-making in river restoration
No full textDuring the last decades public awareness of the limitations of traditional engineering practices and the imperative to conserve nature have led to changes in river management; including river restoration measures. The enlargement of the fluvial corridor is one of the often considered management measures. However, the high-pressure on land-use, the conflict of interests, as well as the uncertainty of vegetation and landscape development scenarios after restoration, can make their implementation difficult. In actual decision-making processes of large river restoration projects, no dynamic long-term modelling approach of potential riparian woody species development exists mainly due to the complexity of interacting driving-processes creating lateral and longitudinal gradients. So far, forest succession models applied to riparian areas are not conceived for river areas found in Central Europe and do not address explicitly environmental influences like nitrogen scarcity or drought stress important for certain riparian systems, nor they cover integrally the vegetation-hydraulics interaction. To support and enhance the decision-making processes in river restoration projects and to provide a better understanding of riparian forest dynamics and its driving-processes, the present thesis develops a coupled model of ecological and hydraulic processes to simulate riparian forest dynamics for Central European conditions, particularly for the case of enlarged fluvial corridors. The developed model RIFOD ('RIparian FOrest Dynamics') – a distribution-based forest succession model (i.e. ecological model) coupled to a quasi-2D hydraulic model – simulates short or long-term riparian forest dynamics at a yearly time step. The model, applied on a 10 times 10 m mesh grid, is spatially-explicit concerning the interactions of the ecological and hydraulic processes and integrates 65 Central European tree and shrub species. The ecological model is based on developments of different upland forest succession models, which were improved, adapted and complemented in regard to the ecological processes in riparian areas, for example concerning regeneration, nitrogen dynamics, soil water availability or flooding stress. At the basis of the modelling of physiological flooding stress response of plants, we carried out an in-depth review of the actual knowledge of the flooding stress response of Central European tree and shrub species. The review could highlight the main biotic and abiotic factors that influence species response and revealed the broad but still vague knowledge about physiological mechanisms and species-specific data of plant response. Based on the above findings, the fuzzy set theory was chosen to model flooding stress response integrating the main abiotic factors (e.g. flooding duration, -depth). The Central European tree and shrub species were classified into flooding tolerance classes by use of clustering analysis based on proxy-data, which allowed us considering indirectly the anatomical, morphological or physiological adaptations to flooding. To model mechanical flooding stress, existing mechanistic models simulating failure resistance to uprooting or stem breakage conceived for wind load studies have been adapted to the case of water flow. Required geometrical characteristics of trees and shrubs, such as crown width and crown heights, were estimated based on available field data, whereas rooting depths in dependence of the growth stage of an individual plant were simulated by developing a quasi-mechanistic vertical root growth model for Central European tree and shrub species. This root growth model allowed also a more realistic simulation of drought stress by calculating root water extraction in relation to the development stage of stand and determining species-specific and development dependent accessibility to groundwater – not integrated in the soil water balance so far. Compared to the situation in uplands, a more realistic modelling of nitrogen availability in riparian areas could be achieved by considering the loss of nitrogen via denitrifcation, as well as the loss of litter due to flooding. In opposition to existing riparian forest succession models, RIFOD considers riparian vegetation not as a purely dependent variable of flooding. Floods may affect vegetation but they are also affected by it, owing to the contribution of vegetation to hydraulic roughness. The coupling of the forest succession model to a quasi 2-D hydraulic model allowed considering this. Moreover, the quasi steady-state model approach allowed emphasizing on the ecological relevant lateral dimension and to make the model spatially explicit in the sense of vegetation-hydraulics interaction. The current version of RIFOD finds its application in riparian areas in which the geomorphological activity of the river is not a dominant process or in case of restoration projects, for widened fluvial corridors with morphologically stable stream channels. Model evaluation (validation and sensitivity analysis) revealed that RIFOD simulates plausibly the ecological gradients observed in the field and the resulting riparian forest dynamics. By applying the model at different lateral fluvial corridor designs at the River Rhone, the consequences of a restoration measure and the change of the hydrological regime for woody vegetation could be illustrated. From a management point of view, the model revealed for example that relative benefits become smaller as the width increases or that in absence of morphological activity (e.g. lateral bank erosion) the hydraulic processes alone are not sufficient for reinitiating riparian forest succession even for high energy streams such as the River Rhone. Moreover, the model allowed verifying and discussing current scientific concepts and hypotheses, as for example the intermediate stress hypothesis. Simulation results revealed that biological diversity is highest between the very low and very severe flooding stress levels confirming the intermediate stress hypothesis involving a trade-off between competitive dominant species which monopolise stable habitats and the few fugitive species that survive high levels of instability. The value of RIFOD relies in the capacity of displaying tendencies of riparian forest dynamics and associated characteristics in function of different fluvial corridor design variants. Moreover, it allows the understanding of processes and patterns in nature by allowing exploring the consequences of a set of explicitly stated assumptions that are too complex to explore by other methods. RIFOD is the first process-based riparian forest dynamics model for Central Europe and can be seen as a step forward into a more integral modelling of the riparian forest dynamics and its processes in view of a decision-aiding tool for large river restoration projects. A future integration of geomorphological processes will allow the application of RIFOD to quasi-natural river conditions.GECO
Amphibian conservation in human shaped environments : landscape dynamics, habitat modeling and metapopulation analyses
Full text linkGlobal biodiversity is experiencing a worrying decline. Habitats destruction, associated to their degradation and fragmentation are among the greatest causes. Amphibians are particularly interesting because they are more threatened and decline more rapidly than either birds or mammals. In this context, the objective of our research is to improve some methodological approaches and offer practical scientific bases for decision making in landscape management and amphibian conservation. Our study focuses on fragmented Swiss landscapes. We developed a method that uses land-cover data and expert knowledge to enable a spatially explicit assessment of 1) the temporal changes in the nature conservation value of the landscape and 2) the rehabilitation potential of the landscape. We applied this Geographical Information Systems (GIS) based approach in the Swiss Rhone plain and we used the years 1900 as the reference state. The method constitutes a helpful tool for communication, decision-making and biological conservation management in landscape planning. Effective and optimal species management strategies can only be formulated after relationships between species distribution and environmental factors have been identified. Concerning amphibians, several approaches exist but they generally suffer from two limitations: 1) the spatial autocorrelation (i.e. the dependency between two observations) in data is rarely explicitly analyzed, even if it may affect the accuracy of species-habitat relationships models. We showed how this spatial autocorrelation can be measured and included in logistic models with the example of the agile frog (Rana dalmatina) in north-eastern Switzerland. We used the Moran's I and the autologistic model (i.e. a logistic model including a measure of the spatial arrangement of the response variables). We found that if spatial autocorrelation is not considered, then conclusions on species-habitat relationships can be incorrect. 2) The effect of landscape on amphibian occurrence in ponds is often assumed to be equal in every direction (isotropic). However, barriers and inhospitable surfaces may reduce movement patterns and the area around ponds accessible to species. This implies that the ideal circular area has in reality a shape depending on the surrounding landscape. We developed a method to determine the effect of habitat variables on amphibian species distribution, considering physical barriers in their movement around ponds. We studied two amphibian species: the common toad (Bufo bufo) and the common frog (Rana temporaria) in the Rhone plain. We demonstrated that reducing the boundaries of circular area following barriers, allowed to compute landscape predictors which better explained species distribution. These results suggested that the proposed approach is more pertinent than the traditional circular buffers analysis. Our results stress the necessity to consider barriers and ecological corridors in species distribution models in order to avoid incorrect inferences. Species distribution models are usually established for a single region. It is generally unknown whether the identified relationships between species distribution and environmental variables can be directly transferred to another geographical area. We examined landscape-level habitat relationships for six amphibian species by measuring correlations with their presence in 655 ponds of five different regions. We analyzed several models by using the information-theoretic approach and the Akaike Information criterion (AIC). For five out of six species, the best models predict that site occupation probability depends on region. Our results suggest that caution is needed when predictions of species occurrence and species management strategies are done using models built in other geographic regions. We also observed that connectivity was generally more explicative than landscape variables. In addition, we found that the spatial scale at which habitat affected species occurrence varied from pond to several km around ponds. Management strategies for amphibian conservation should be conducted taking into account the geographic context, connectivity of ponds and habitat characteristics at multiple spatial scales. Finally, we demonstrated that the landscape, separating patches in metapopulation models, has to be considered in order to avoid incorrect conclusions on population viability analyses. We explored how patch occupancy is sensitive to Euclidean (shortest) versus a landscape-based distance (least-cost). We found: 1) from a theoretical standpoint, that inter-patch landscape affects patch occupancy; 2) from a practical and conservation standpoints, which patches should be considered in priority for landscape management. The approach was illustrated in the case of two metapopulations of the Yellow-bellied Toad in the Rhone plain. We applied successfully the developed practical approaches to the case of several amphibian species, but they can doubtlessly be extended to any species functioning on a spatially defined patch basis (e.g. pond, nesting place, den …), structured as a metapopulation and affected by landscape structure during movement. By improving and combining spatially explicit approaches, we are more likely to provide wildlife managers with tools for valuable decision making.LASI
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