Gil-Tena A., Morán-Ordóñez A., Comas L., Retana J., Vayreda J., Brotons L. (2019) A quantitative assessment of mid-term risks of global change on forests in Western Mediterranean Europe. Regional Environmental Change. 19: 819-831.LinkDoi: 10.1007/s10113-018-1437-0
Assessment of potential forests’ threats due to multiple global change components is urgently needed since increasing exposure to them could undermine their future persistence. We aim to assess the risks to the persistence of monospecific forests in Western Mediterranean Europe posed by climate change, fire, and land-use changes (i.e., deforestation) in the short and medium terms (horizon 2040). We specifically evaluate whether the degree of risk related to the likelihood of hazard occurrence varies depending on seral stage, tree species, and climate gradients. We performed the risk assessment on forests of Catalonia (NE Spain) through a combination of correlative and process-based modeling approaches and future global change scenarios. Overall, climate suitability of forests showed a general decrease by 2040, with the exception of xeric Pinus halepensis forests mainly distributed in the driest climate of the study area. Forest stands dominated by low drought-tolerant species were at higher risk of losing climatic suitability than forests dominated by Mediterranean species. The highest fire and deforestation risks were predicted for forest stands in dry climate where human pressures are higher. Nevertheless, high deforestation risk was also attained outside the driest areas. Deforestation risk was lower in old-growth than in younger stands, whereas old-growth forests in the Wet climate or dominated by Pinus sylvestris were projected to be at higher fire risk than younger forests. Our results suggest that conservation actions should target forest stands in dry climate. Moreover, old-growth forest stands should also be prioritized due to their particular sensitivity to disturbances and their high ecological value. © 2018, Springer-Verlag GmbH Germany, part of Springer Nature.
Morán-Ordóñez A., Roces-Díaz J.V., Otsu K., Ameztegui A., Coll L., Lefevre F., Retana J., Brotons L. (2019) The use of scenarios and models to evaluate the future of nature values and ecosystem services in Mediterranean forests. Regional Environmental Change. 19: 415-428.LinkDoi: 10.1007/s10113-018-1408-5
Science and society are increasingly interested in predicting the effects of global change and socio-economic development on natural systems, to ensure maintenance of both ecosystems and human well-being. The Intergovernmental Platform on Biodiversity and Ecosystem Services has identified the combination of ecological modelling and scenario forecasting as key to improving our understanding of those effects, by evaluating the relationships and feedbacks between direct and indirect drivers of change, biodiversity, and ecosystem services. Using as case study the forests of the Mediterranean basin (complex socio-ecological systems of high social and conservation value), we reviewed the literature to assess (1) what are the modelling approaches most commonly used to predict the condition and trends of biodiversity and ecosystem services under future scenarios of global change, (2) what are the drivers of change considered in future scenarios and at what scales, and (3) what are the nature and ecosystem service indicators most commonly evaluated. Our review shows that forecasting studies make relatively little use of modelling approaches accounting for actual ecological processes and feedbacks between different socio-ecological sectors; predictions are generally made on the basis of a single (mainly climate) or a few drivers of change. In general, there is a bias in the set of nature and ecosystem service indicators assessed. In particular, cultural services and human well-being are greatly underrepresented in the literature. We argue that these shortfalls hamper our capacity to make the best use of predictive tools to inform decision-making in the context of global change. © 2018, Springer-Verlag GmbH Germany, part of Springer Nature.
Doblas-Miranda, E., Alonso, R., Arnan, X., Bermejo, V., Brotons, L., de las Heras, J., Estiarte, M., Hódar, J.A., Llorens, P., Lloret, F., López-Serrano, F.R., Martínez-Vilalta, J., Moya, D., Peñuelas, J., Pino, J., Rodrigo, A., Roura-Pascual, N., Valladares, F., Vilà, M., Zamora, R., Retana, J. (2017) A review of the combination among global change factors in forests, shrublands and pastures of the Mediterranean Region: Beyond drought effects. Global and Planetary Change. 148: 42-54.LinkDoi: 10.1016/j.gloplacha.2016.11.012
Regos A., Aquilué N., López I., Codina M., Retana J., Brotons L. (2016) Synergies Between Forest Biomass Extraction for Bioenergy and Fire Suppression in Mediterranean Ecosystems: Insights from a Storyline-and-Simulation Approach. Ecosystems. 19: 786-802.LinkDoi: 10.1007/s10021-016-9968-z
Increases in fire impacts over many regions of the world have led to large-scale investments in fire-suppression efforts. There is increasing recognition that biomass extraction for energy purposes may become an important forest-management practice in fire-prone ecosystems. However, at present, very few studies have explicitly assessed biomass extraction as a fuel treatment at landscape scale. Here, we use a landscape fire-succession model in Catalonia (NE Spain) to quantitatively evaluate the potential effects of a biomass extraction-based strategy on essential fire-regime attributes after considering different levels of fire suppression, biomass extraction intensity, and spatial allocation of such efforts. Our simulations indicated that the effectiveness (area suppressed in relation to expected area to burn) at suppressing wildfires was determined by extraction intensity, spatial allocation of the extraction effort, and the fire-suppression levels involved. Indeed, the highest suppressed-area values were found with lower harvesting intensities, especially under high fire-suppression capabilities and strategies focused on bioenergy goals (figures close to 0.7). However, the leverage (area suppressed in relation to managed area) was higher when the treatments were based on the fire-prevention strategy and focused on high-fire-risk areas (up to 0.45) than with treatment designed for energy reasons (lower than 0.15). We conclude that biomass extraction for energy purposes has the potential to induce changes in fire regimes and can therefore be considered a cost-effective landscape-level fuel-reduction treatment. However, our results suggest that large-scale biomass extraction may be needed if significant changes in fire regimes are to be expected. © 2016, Springer Science+Business Media New York.
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.LinkDoi: 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.
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.LinkDoi: 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).
Doblas-Miranda E., Martinez-Vilalta J., Lloret F., Alvarez A., Avila A., Bonet F.J., Brotons L., Castro J., Curiel Yuste J., Diaz M., Ferrandis P., Garcia-Hurtado E., Iriondo J.M., Keenan T.F., Latron J., Llusia J., Loepfe L., Mayol M., More G., Moya D., Penuelas J., Pons X., Poyatos R., Sardans J., Sus O., Vallejo V.R., Vayreda J., Retana J. (0) Reassessing global change research priorities in mediterranean terrestrial ecosystems: How far have we come and where do we go from here?. Global Ecology and Biogeography. 24: 25-43.LinkDoi: 10.1111/geb.12224
Aim: Mediterranean terrestrial ecosystems serve as reference laboratories for the investigation of global change because of their transitional climate, the high spatiotemporal variability of their environmental conditions, a rich and unique biodiversity and a wide range of socio-economic conditions. As scientific development and environmental pressures increase, it is increasingly necessary to evaluate recent progress and to challenge research priorities in the face of global change. Location: Mediterranean terrestrial ecosystems. Methods: This article revisits the research priorities proposed in a 1998 assessment. Results: A new set of research priorities is proposed: (1) to establish the role of the landscape mosaic on fire-spread; (2) to further research the combined effect of different drivers on pest expansion; (3) to address the interaction between drivers of global change and recent forest management practices; (4) to obtain more realistic information on the impacts of global change and ecosystem services; (5) to assess forest mortality events associated with climatic extremes; (6) to focus global change research on identifying and managing vulnerable areas; (7) to use the functional traits concept to study resilience after disturbance; (8) to study the relationship between genotypic and phenotypic diversity as a source of forest resilience; (9) to understand the balance between C storage and water resources; (10) to analyse the interplay between landscape-scale processes and biodiversity conservation; (11) to refine models by including interactions between drivers and socio-economic contexts; (12) to understand forest-atmosphere feedbacks; (13) to represent key mechanisms linking plant hydraulics with landscape hydrology. Main conclusions: (1) The interactive nature of different global change drivers remains poorly understood. (2) There is a critical need for the rapid development of regional- and global-scale models that are more tightly connected with large-scale experiments, data networks and management practice. (3) More attention should be directed to drought-related forest decline and the current relevance of historical land use.
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