Aizpurua O., Paquet J.-Y., Brotons L., Titeux N. (2014) Optimising long-term monitoring projects for species distribution modelling: How atlas data may help. Ecography. : 0-0.EnllaçDoi: 10.1111/ecog.00749
Long-term biodiversity monitoring data are mainly used to estimate changes in species occupancy or abundance over time, but they may also be incorporated into predictive models to document species distributions in space. Although changes in occupancy or abundance may be estimated from a relatively limited number of sampling units, small sample size may lead to inaccurate spatial models and maps of predicted species distributions. We provide a methodological approach to estimate the minimum sample size needed in monitoring projects to produce accurate species distribution models and maps. The method assumes that monitoring data are not yet available when sampling strategies are to be designed and is based on external distribution data from atlas projects. Atlas data are typically collected in a large number of sampling units during a restricted timeframe and are often similar in nature to the information gathered from long-term monitoring projects. The large number of sampling units in atlas projects makes it possible to simulate a broad gradient of sample sizes in monitoring data and to examine how the number of sampling units influences the accuracy of the models. We apply the method to several bird species using data from a regional breeding bird atlas. We explore the effect of prevalence, range size and habitat specialization of the species on the sample size needed to generate accurate models. Model accuracy is sensitive to particularly small sample sizes and levels off beyond a sufficiently large number of sampling units that varies among species depending mainly on their prevalence. The integration of spatial modelling techniques into monitoring projects is a cost-effective approach as it offers the possibility to estimate the dynamics of species distributions in space and over time. We believe our innovative method will help in the sampling design of future monitoring projects aiming to achieve such integration. © 2014 The Authors.
Cardador L., De Caceres M., Bota G., Giralt D., Casas F., Arroyo B., Mougeot F., Cantero-Martiez C., Moncunill J., Butler S.J., Brotons L. (2014) A resource-based modelling framework to assess habitat suitability for steppe birds in semiarid Mediterranean agricultural systems. PLoS ONE. 9: 0-0.EnllaçDoi: 10.1371/journal.pone.0092790
European agriculture is undergoing widespread changes that are likely to have profound impacts on farmland biodiversity. The development of tools that allow an assessment of the potential biodiversity effects of different land-use alternatives before changes occur is fundamental to guiding management decisions. In this study, we develop a resource-based model framework to estimate habitat suitability for target species, according to simple information on species' key resource requirements (diet, foraging habitat and nesting site), and examine whether it can be used to link land-use and local species' distribution. We take as a study case four steppe bird species in a lowland area of the north-eastern Iberian Peninsula. We also compare the performance of our resource-based approach to that obtained through habitat-based models relating species' occurrence and land-cover variables. Further, we use our resource-based approach to predict the effects that change in farming systems can have on farmland bird habitat suitability and compare these predictions with those obtained using the habitat-based models. Habitat suitability estimates generated by our resource-based models performed similarly (and better for one study species) than habitat based-models when predicting current species distribution. Moderate prediction success was achieved for three out of four species considered by resource-based models and for two of four by habitat-based models. Although, there is potential for improving the performance of resource-based models, they provide a structure for using available knowledge of the functional links between agricultural practices, provision of key resources and the response of organisms to predict potential effects of changing land-uses in a variety of context or the impacts of changes such as altered management practices that are not easily incorporated into habitat-based models. © 2014 Cardador et al.
Herrando S., Anton M., Sarda-Palomera F., Bota G., Gregory R.D., Brotons L. (2014) Indicators of the impact of land use changes using large-scale bird surveys: Land abandonment in a Mediterranean region. Ecological Indicators. 45: 235-244.EnllaçDoi: 10.1016/j.ecolind.2014.04.011
Developing sound indicators of biodiversity impact has been identified as a critical step towards our understanding of how global change components are affecting the environment across the globe. Land abandonment is recognized as a major component of global change in the Mediterranean basin, however, we lack adequate, quantitative, indicators of its impact on biodiversity. An appealing approach to develop biodiversity indicators is the use of large-scale bird monitoring projects, an important source of information that is already available in many countries. In this study we develop a method to quantify the impact of the two main processes associated with land abandonment in the Mediterranean region, namely the abandonment of farmland, which produces a shift from cultivated land to open natural habitats, and the encroachment by vegetation usually associated with reductions in livestock grazing and wood harvesting practices. We used data from bird atlas and monitoring schemes in Catalonia (north-east Iberian Peninsula) to characterize species' population response to these processes by means of detecting quantitative changes in relative abundances along a gradient ranging from habitats not affected by a given driving force to those that arise as a consequence of such force. We then generated multi-species indicators of the impact of these land use changes using these specific population responses to calibrate the relative contribution of each species in the composite index. The temporal patterns depicted by the two indicators in the period 2002-2011 show that vegetation encroachment did have a significant impact on bird communities, whereas any noticeable effect of farmland abandonment on bird populations was observed. The methodology proposed here could be employed to develop indicators capable to track biological impacts of land use change on an annual basis and inform decision-makers about the rate of increase or decrease on wildlife populations. © 2014 Elsevier Ltd.
Regos A., Aquilue N., Retana J., De Caceres M., Brotons L. (2014) Using unplanned fires to help suppressing future large fires in mediterranean forests. PLoS ONE. 9: 0-0.EnllaçDoi: 10.1371/journal.pone.0094906
Despite the huge resources invested in fire suppression, the impact of wildfires has considerably increased across the Mediterranean region since the second half of the 20th century. Modulating fire suppression efforts in mild weather conditions is an appealing but hotly-debated strategy to use unplanned fires and associated fuel reduction to create opportunities for suppression of large fires in future adverse weather conditions. Using a spatially-explicit fire-succession model developed for Catalonia (Spain), we assessed this opportunistic policy by using two fire suppression strategies that reproduce how firefighters in extreme weather conditions exploit previous fire scars as firefighting opportunities. We designed scenarios by combining different levels of fire suppression efficiency and climatic severity for a 50-year period (2000-2050). An opportunistic fire suppression policy induced large-scale changes in fire regimes and decreased the area burnt under extreme climate conditions, but only accounted for up to 18-22% of the area to be burnt in reference scenarios. The area suppressed in adverse years tended to increase in scenarios with increasing amounts of area burnt during years dominated by mild weather. Climate change had counterintuitive effects on opportunistic fire suppression strategies. Climate warming increased the incidence of large fires under uncontrolled conditions but also indirectly increased opportunities for enhanced fire suppression. Therefore, to shift fire suppression opportunities from adverse to mild years, we would require a disproportionately large amount of area burnt in mild years. We conclude that the strategic planning of fire suppression resources has the potential to become an important cost-effective fuel-reduction strategy at large spatial scale. We do however suggest that this strategy should probably be accompanied by other fuel-reduction treatments applied at broad scales if large-scale changes in fire regimes are to be achieved, especially in the wider context of climate change. © 2014 Regos et al.
Regos A., Dominguez J., Gil-Tena A., Brotons L., Ninyerola M., Pons X. (2014) Rural abandoned landscapes and bird assemblages: winners and losers in the rewilding of a marginal mountain area (NW Spain). Regional Environmental Change. : 0-0.EnllaçDoi: 10.1007/s10113-014-0740-7
In many regions of Europe, large-scale socio-economic changes have led to the abandonment of rural activities and a gradual takeover of natural vegetation. It is important to assess the relative positive and negative effects of land abandonment on particular areas where the low-intensity farming is no longer socially or economically viable in order to quantify the potential conservation costs and benefits of a rewilding as a land-use management policy. During the period 2000–2010, we studied the land-use/land-cover changes in an abandoned mountain landscape (Galicia, NW Spain) and evaluated the effects on breeding bird occurrence and distribution. For this purpose, we analysed remotely sensed data-derived maps in combination with data obtained from bird censuses carried out in 2000 and 2010 at both landscape and census plot scale. The results revealed a gradient of change from bare ground and open shrubland to closed shrubland and woodland. Thirteen shrubland and forest bird species showed a significant increase (including species of conservation concern such as Turtle Dove, Dartford Warbler and Western Bonelli’s Warbler), while four ecotone and open-habitat species (e.g. Red-backed Shrike) showed a significant negative trend. In conclusion, rewilding appears to have overall positive effects on biodiversity and should be considered by policy makers as alternative land-use strategy in marginal mountain areas, particularly if they have been historically affected by wildfires. Fire management aimed at favouring the creation of small burned areas in progressively closed landscapes derived from rewilding may be a complementary alternative to maintain open habitats in these areas.
Santos X., Mateos E., Bros V., Brotons L., De Mas E., Herraiz J.A., Herrando S., Mino A., Olmo-Vidal J.M., Quesada J., Ribes J., Sabate S., Sauras-Yera T., Serra A., Ramon Vallejo V., Vinolas A. (2014) Is response to fire influenced by dietary specialization and mobility? A comparative study with multiple animal assemblages. PLoS ONE. 9: 0-0.EnllaçDoi: 10.1371/journal.pone.0088224
Fire is a major agent involved in landscape transformation and an indirect cause of changes in species composition. Responses to fire may vary greatly depending on life histories and functional traits of species. We have examined the taxonomic and functional responses to fire of eight taxonomic animal groups displaying a gradient of dietary and mobility patterns: Gastropoda, Heteroptera, Formicidae, Coleoptera, Araneae, Orthoptera, Reptilia and Aves. The fieldwork was conducted in a Mediterranean protected area on 3 sites (one unburnt and two burnt with different postfire management practices) with five replicates per site. We collected information from 4606 specimens from 274 animal species. Similarity in species composition and abundance between areas was measured by the Bray-Curtis index and ANOSIM, and comparisons between animal and plant responses by Mantel tests. We analyze whether groups with the highest percentage of omnivorous species, these species being more generalist in their dietary habits, show weak responses to fire (i.e. more similarity between burnt and unburnt areas), and independent responses to changes in vegetation. We also explore how mobility, i.e. dispersal ability, influences responses to fire. Our results demonstrate that differences in species composition and abundance between burnt and unburnt areas differed among groups. We found a tendency towards presenting lower differences between areas for groups with higher percentages of omnivorous species. Moreover, taxa with a higher percentage of omnivorous species had significantly more independent responses of changes in vegetation. High- (e.g. Aves) and low-mobility (e.g. Gastropoda) groups had the strongest responses to fire (higher R scores of the ANOSIM); however, we failed to find a significant general pattern with all the groups according to their mobility. Our results partially support the idea that functional traits underlie the response of organisms to environmental changes caused by fire. © 2014 Santos et al.
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