Brotons L., Aquilue N., de Caceres M., Fortin M.-J., Fall A. (2013) How Fire History, Fire Suppression Practices and Climate Change Affect Wildfire Regimes in Mediterranean Landscapes. PLoS ONE. 8: 0-0.EnllaçDoi: 10.1371/journal.pone.0062392
Available data show that future changes in global change drivers may lead to an increasing impact of fires on terrestrial ecosystems worldwide. Yet, fire regime changes in highly humanised fire-prone regions are difficult to predict because fire effects may be heavily mediated by human activities We investigated the role of fire suppression strategies in synergy with climate change on the resulting fire regimes in Catalonia (north-eastern Spain). We used a spatially-explicit fire-succession model at the landscape level to test whether the use of different firefighting opportunities related to observed reductions in fire spread rates and effective fire sizes, and hence changes in the fire regime. We calibrated this model with data from a period with weak firefighting and later assess the potential for suppression strategies to modify fire regimes expected under different levels of climate change. When comparing simulations with observed fire statistics from an eleven-year period with firefighting strategies in place, our results showed that, at least in two of the three sub-regions analysed, the observed fire regime could not be reproduced unless taking into account the effects of fire suppression. Fire regime descriptors were highly dependent on climate change scenarios, with a general trend, under baseline scenarios without fire suppression, to large-scale increases in area burnt. Fire suppression strategies had a strong capacity to compensate for climate change effects. However, strong active fire suppression was necessary to accomplish such compensation, while more opportunistic fire suppression strategies derived from recent fire history only had a variable, but generally weak, potential for compensation of enhanced fire impacts under climate change. The concept of fire regime in the Mediterranean is probably better interpreted as a highly dynamic process in which the main determinants of fire are rapidly modified by changes in landscape, climate and socioeconomic factors such as fire suppression strategies. © 2013 Brotons et al.
Capinha C., Brotons L., Anastácio P. (2013) Geographical variability in propagule pressure and climatic suitability explain the European distribution of two highly invasive crayfish. Journal of Biogeography. 40: 548-558.EnllaçDoi: 10.1111/jbi.12025
Aim: We assess the relative contribution of human, biological and climatic factors in explaining the colonization success of two highly invasive freshwater decapods: the signal crayfish (Pacifastacus leniusculus) and the red swamp crayfish (Procambarus clarkii). Location: Europe. Methods: We used boosted regression trees to evaluate the relative influence of, and relationship between, the invader's current pattern of distribution and a set of spatially explicit variables considered important to their colonization success. These variables are related to four well-known invasion hypotheses, namely the role of propagule pressure, climate matching, biotic resistance from known competitors, and human disturbance. Results: Model predictions attained a high accuracy for the two invaders (mean AUC ≥ 0.91). Propagule pressure and climatic suitability were identified as the primary drivers of colonization, but the former had a much higher relative influence on the red swamp crayfish. Climate matching was shown to have limited predictive value and climatic suitability models based on occurrences from other invaded areas had consistently higher relative explanatory power than models based on native range data. Biotic resistance and human disturbance were also shown to be weak predictors of the distribution of the two invaders. Main conclusions: These results contribute to our general understanding of the factors that enable certain species to become notable invaders. Being primarily driven by propagule pressure and climatic suitability, we expect that, given their continued dispersal, the future distribution of these problematic decapods in Europe will increasingly represent their fundamental climatic niche. © 2012 Blackwell Publishing Ltd.
Carnicer J., Brotons L., Herrando S., Sol D. (2013) Improved empirical tests of area-heterogeneity tradeoffs. Proceedings of the National Academy of Sciences of the United States of America. 110: 0-0.EnllaçDoi: 10.1073/pnas.1222681110
[No abstract available]
De Caceres M., Brotons L., Aquilue N., Fortin M.-J. (2013) The combined effects of land-use legacies and novel fire regimes on bird distributions in the Mediterranean. Journal of Biogeography. 40: 1535-1547.EnllaçDoi: 10.1111/jbi.12111
Aim: We investigate first whether fire regimes resulting from the combination of climate change and fire-fighting policy may affect species distributions in Mediterranean landscapes, and second to what extent distributional dynamics may be constrained by the spatial legacy of historical land use. Location: Catalonia (north-eastern Spain). Methods: We modelled the distributional responses of 64 forest and open-habitat bird species to nine fire-regime scenarios, defined by combining different levels of climate change and fire suppression efficiency. A fire-succession model was used to stochastically simulate land-cover changes between 2000 and 2050 under these scenarios. We used species distribution models to predict habitat suitability and occupancy dynamics under either no dispersal or full dispersal assumptions. Results: Under many simulated scenarios, the succession from shrubland to forest dominated over the creation of new low-vegetation areas derived from wildfires. Consequently, open-habitat specialists were the group most affected by losses of suitable habitat. Fire regimes obtained under scenarios including high fire suppression efficiency resulted in a larger number of bird species experiencing reductions in their distribution area. Main conclusions: Anthropogenic factors, such as historical land-use change and fire suppression, can drive regional distribution dynamics in directions opposite to those expected from climatic trends. This raises the question of what drivers and interactions should be given priority in the prediction of biodiversity responses to global change at the regional scale. © 2013 Blackwell Publishing Ltd.
Doblas-Miranda E., Rovira P., Brotons L., Martinez-Vilalta J., Retana J., Pla M., Vayreda J. (2013) Soil carbon stocks and their variability across the forests, shrublands and grasslands of peninsular Spain. Biogeosciences. 10: 8353-8361.EnllaçDoi: 10.5194/bg-10-8353-2013
Accurate estimates of C stocks and fluxes of soil organic carbon (SOC) are needed to assess the impact of climate and land use change on soil C uptake and soil C emissions to the atmosphere. Here, we present an assessment of SOC stocks in forests, shrublands and grasslands of peninsular Spain based on field measurements in more than 900 soil profiles. SOC to a depth of 1 m was modelled as a function of vegetation cover, mean annual temperature, total annual precipitation, elevation and the interaction between temperature and elevation, while latitude and longitude were used to model the correlation structure of the errors. The resulting statistical model was used to estimate SOC in the ∼8 million pixels of the Spanish Forest Map (29.3 × 106 ha). We present what we believe is the most reliable estimation of current SOC in forests, shrublands and grasslands of peninsular Spain thus far, based on the use of spatial modelling, the high number of profiles and the validity and refinement of the data layers employed. Mean concentration of SOC was 8.7 kg m-2, ranging from 2.3 kg m-2 in dry Mediterranean areas to 20.4 kg m -2 in wetter northern locations. This value corresponds to a total stock of 2.544 Tg SOC, which is four times the amount of C estimated to be stored in the biomass of Spanish forests. Climate and vegetation cover were the main variables influencing SOC, with important ecological implications for peninsular Spanish ecosystems in the face of global change. The fact that SOC was positively related to annual precipitation and negatively related to mean annual temperature suggests that future climate change predictions of increased temperature and reduced precipitation may strongly reduce the potential of Spanish soils as C sinks. However, this may be mediated by changes in vegetation cover (e.g. by favouring the development of forests associated to higher SOC values) and exacerbated by perturbations such as fire. The estimations presented here provide a baseline to estimate future changes in soil C stocks and to assess their vulnerability to key global change drivers, and should inform future actions aimed at the conservation and management of C stocks. © 2013 Author(s).
Guisan A., Tingley R., Baumgartner J.B., Naujokaitis-Lewis I., Sutcliffe P.R., Tulloch A.I.T., Regan T.J., Brotons L., Mcdonald-Madden E., Mantyka-Pringle C., Martin T.G., Rhodes J.R., Maggini R., Setterfield S.A., Elith J., Schwartz M.W., Wintle B.A., Broennimann O., Austin M., Ferrier S., Kearney M.R., Possingham H.P., Buckley Y.M. (2013) Predicting species distributions for conservation decisions. Ecology Letters. 16: 1424-1435.EnllaçDoi: 10.1111/ele.12189
Species distribution models (SDMs) are increasingly proposed to support conservation decision making. However, evidence of SDMs supporting solutions for on-ground conservation problems is still scarce in the scientific literature. Here, we show that successful examples exist but are still largely hidden in the grey literature, and thus less accessible for analysis and learning. Furthermore, the decision framework within which SDMs are used is rarely made explicit. Using case studies from biological invasions, identification of critical habitats, reserve selection and translocation of endangered species, we propose that SDMs may be tailored to suit a range of decision-making contexts when used within a structured and transparent decision-making process. To construct appropriate SDMs to more effectively guide conservation actions, modellers need to better understand the decision process, and decision makers need to provide feedback to modellers regarding the actual use of SDMs to support conservation decisions. This could be facilitated by individuals or institutions playing the role of 'translators' between modellers and decision makers. We encourage species distribution modellers to get involved in real decision-making processes that will benefit from their technical input; this strategy has the potential to better bridge theory and practice, and contribute to improve both scientific knowledge and conservation outcomes. © 2013 The Authors. Ecology Letters published by John Wiley & Sons Ltd and CNRS.
Leung B., Roura-Pascual N., Bacher S., Heikkila J., Brotons L., Burgman M.A., Dehnen-Schmutz K., Essl F., Hulme P.E., Richardson D.M., Sol D., Vila M. (2013) Addressing a critique of the TEASI framework for invasive species risk assessment. Ecology Letters. 16: 1415-14.EnllaçDoi: 10.1111/ele.12172
We address criticism that the Transport, Establishment, Abundance, Spread, Impact (TEASI) framework does not facilitate objective mapping of risk assessment methods nor defines best practice. We explain why TEASI is appropriate for mapping, despite inherent challenges, and how TEASI offers considerations for best practices, rather than suggesting one best practice. © 2013 John Wiley & Sons Ltd/CNRS.
Rost J., Hutto R.L., Brotons L., Pons P. (2013) Comparing the effect of salvage logging on birds in the Mediterranean Basin and the Rocky Mountains: Common patterns, different conservation implications. Biological Conservation. 158: 7-13.EnllaçDoi: 10.1016/j.biocon.2012.08.022
Postfire salvage logging is currently a controversial issue because of the impact that the removal of snags has on ecosystem structure and function. Although it is a common practice worldwide, the absence of comparisons across regions hinders the development of broad generalizations. Here we compare bird response to postfire salvage logging in two regions with significant differences in landscape and bird communities, the Mediterranean Basin and the Rocky Mountains. The Mediterranean Basin features a landscape dominated by a mosaic of small-sized forests, farmland and shrublands, while the Rocky Mountains have large extensions of continuous forests. Bird conservation priorities are also different. In the Mediterranean Basin, priorities are oriented toward farmland birds, while they are oriented toward fire-specialists in the Rocky Mountains. We used databases describing bird species occurrence in burned forests from both regions and defined three groups of species based on their level of association with snags. We then compared the richness of each group among logged and unlogged sites, and also between regions. We found a higher proportion of species that showed some degree of association with snags in burned forests of the Rocky Mountains than in the Mediterranean Basin. Highly snag-associated birds from both regions showed a common negative response to salvage logging. Not snag-associated species increased in salvaged areas, but only in the Mediterranean Basin. The general negative effect of salvage logging on forest-dwelling species that are associated with trees or snags is a noteworthy pattern given the big differences between regions. Nevertheless, in the Mediterranean, some threatened farmland species benefit from logging, so the overall effect of the removal of snags appears to be relatively more detrimental to birds in the Rocky Mountains. © 2012 Elsevier Ltd.
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