How Fire History, Fire Suppression Practices and Climate Change Affect Wildfire Regimes in Mediterranean Landscapes

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

Using unplanned fires to help suppressing future large fires in Mediterranean forests

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.This study was supported by the research projects BIONOVEL (CGL2011-29539/BOS) and MONTES (CSD2008-00040) funded by the Spanish Ministry of Education and Science

Managing for the unexpected: Building resilient forest landscapes to cope with global change

Natural disturbances exacerbated by novel climate regimes are increasing worldwide, threatening the ability of forest ecosystems to mitigate global warming through car-bon sequestration and to provide other key ecosystem services. One way to cope with unknown disturbance events is to promote the ecological resilience of the forest by increasing both functional trait and structural diversity and by fostering functional connectivity of the landscape to ensure a rapid and efficient self- reorganization of the system. We investigated how expected and unexpected variations in climate and biotic disturbances affect ecological resilience and carbon storage in a forested region in southeastern Canada. Using a process- based forest landscape model (LANDIS-II), we simulated ecosystem responses to climate change and insect outbreaks under dif-ferent forest policy scenarios—including a novel approach based on functional diver-sification and network analysis—and tested how the potentially most damaging insect pests interact with changes in forest composition and structure due to changing cli-mate and management. We found that climate warming, lengthening the vegetation season, will increase forest productivity and carbon storage, but unexpected impacts of drought and insect outbreaks will drastically reduce such variables. Generalist, non- native insects feeding on hardwood are the most damaging biotic agents for our region, and their monitoring and early detection should be a priority for forest au-thorities. Higher forest diversity driven by climate-smart management and fostered by climate change that promotes warm-adapted species, might increase disturbance severity. However, alternative forest policy scenarios led to a higher functional and structural diversity as well as functional connectivity—and thus to higher ecological resilience—than conventional management. Our results demonstrate that adopting a landscape-scale perspective by planning interventions strategically in space and adopting a functional trait approach to diversify forests is promising for enhancing ecological resilience under unexpected global change stressors.MM received funding from the Swiss National Science Foundation (grant n.175101) and the European Union’s Horizon 2020 research and innovation program under the Marie Skłodowska-Curie framework (grant n.891671, REINFORCE project). NA was supported by a Juan de la Cierva fellowship of the Spanish Ministry of Science and Innovation (FCJ2020-046387-I). This work has also been supported by funding to NA and MM from the Canada Research Chair in Forest Resilience to Global Changes attributed to CM. MJF acknowledges the support of the Canada Research Chair in Spatial Ecology

Mountain farmland protection and fire-smart management jointly reduce fire hazard and enhance biodiversity and carbon sequestration

The environmental and socio-economic impacts of wildfires are foreseen to increase across southern Europe over the next decades regardless of increasing resources allocated for fire suppression. This study aims to identify fire-smart management strategies that promote wildfire hazard reduction, climate regulation ecosystem service and biodiversity conservation. Here we simulate fire-landscape dynamics, carbon sequestration and species distribution (116 vertebrates) in the Transboundary Biosphere Reserve Gerês-Xurés (NW Iberia). We envisage 11 scenarios resulting from different management strategies following four storylines: Business-as-usual (BAU), expansion of High Nature Value farmlands (HNVf), Fire-Smart forest management, and HNVf plus Fire-Smart. Fire-landscape simulations reveal an increase of up to 25% of annual burned area. HNVf areas may counterbalance this increasing fire impact, especially when combined with fire-smart strategies (reductions of up to 50% between 2031 and 2050). The Fire-Smart and BAU scenarios attain the highest estimates for total carbon sequestered. A decrease in habitat suitability (around 18%) since 1990 is predicted for species of conservation concern under the BAU scenario, while HNVf would support the best outcomes in terms of conservation. Our study highlights the benefits of integrating fire hazard control, ecosystem service supply and biodiversity conservation to inform better decision-making in mountain landscapes of Southern Europe.This research work was funded by national funds through the FCT – Foundation for Science and Technology, I.P., under the FirESmart project (PCIF/MOG/0083/2017) and the project INMODES (CGL2017- 89999-C2-2-R) funded by the Spanish Ministry of Science and Innovation. A.R. was funded by the Xunta de Galicia (postdoctoral fellowship ED481B2016/084-0) and IACOBUS program (INTERREG VA España – Portugal, POCTEP 2014-2020). J.D. and A.R. thanks the support of Xunta de Galicia ED431B 2018/36. Â. Sil received support from the Portuguese Foundation for Science and Technology (FCT) through Ph.D. Grant SFRH/BD/132838/2017, funded by the Ministry of Science, Technology and Higher Education, and by the European Social Fund - Operational Program Human Capital within the 2014- 2020 EU Strategic Framework. FM-F has a contract from FCT (ref. DL57/2016/CP1440/CT0010). We thank to Adrián Lamosa Torres, Xosé Pardavila and Alberto Gil for their help during fieldwork in Xurés and Rafael Vázquez for providing additional data for amphibians and reptiles.info:eu-repo/semantics/publishedVersio

Using fire to enhance rewilding when agricultural policies fail

Rewilding has been proposed as an opportunity for biodiversity conservation in abandoned landscapes. However, rewilding is challenged by the increasing fire risk associated with more flammable landscapes, and the loss of open-habitat specialist species. Contrastingly, supporting High Nature Value farmlands (HNVf) has been also highlighted as a valuable option, but the effective implementation of agricultural policies often fails leading to uncertain scenarios wherein the effects of wildfire management remain largely unexplored. Herein, we simulated fire-landscape dynamics to evaluate howfire suppression scenarios affect fire regime and biodiversity (102 species of vertebrates) under rewilding and HNVf policies in the future (2050), in a transnational biosphere reserve (Gerês-Xurés Mountains, Portugal-Spain). Rewilding and HNVf scenarios were modulated by three different levels of fire suppression effectiveness. Then, we quantified scenario effects on fire regime (burned and suppressed areas) and biodiversity (habitat suitability change for 2050). Simulations confirm HNVf as a longterm opportunity for fire suppression (up to 30,000 ha of additional suppressed areas between 2031 and 2050 in comparison to rewilding scenario) and for conservation (benefiting around 60% of species). Rewilding benefits some species (20%), including critically endangered, vulnerable and endemic taxa, while several species (33%) also profit from open habitats created by fire. Although HNVf remains the best scenario, rewilding reinforced by low fire suppression management may provide a nature-based solution when societal support through agricultural policies failsinfo:eu-repo/semantics/acceptedVersio

Fire and biodiversity in the Anthropocene

The workshop leading to this paper was funded by the Centre Tecnològic Forestal de Catalunya and the ARC Centre of Excellence for Environmental Decisions. L.T.K. was supported by a Victorian Postdoctoral Research Fellowship (Victorian Government), a Centenary Fellowship (University of Melbourne), and an Australian Research Council Linkage Project Grant (LP150100765). A.R. was supported by the Xunta de Galicia (Postdoctoral Fellowship ED481B2016/084-0) and the Foundation for Science and Technology under the FirESmart project (PCIF/MOG/0083/2017). A.L.S. was supported by a Marie Skłodowska-Curie Individual Fellowship (746191) under the European Union Horizon 2020 Programme for Research and Innovation. L.R. was supported by the Australian Government’s National Environmental Science Program through the Threatened Species Recovery Hub. L.B. was partially supported by the Spanish Government through the INMODES (CGL2014-59742-C2-2-R) and the ERANET-SUMFORESTS project FutureBioEcon (PCIN-2017-052). This research was supported in part by the U.S. Department of Agriculture, Forest Service, Pacific Southwest Research Station.BACKGROUND Fire has shaped the diversity of life on Earth for millions of years. Variation in fire regimes continues to be a source of biodiversity across the globe, and many plants, animals, and ecosystems depend on particular temporal and spatial patterns of fire. Although people have been using fire to modify environments for millennia, the combined effects of human activities are now changing patterns of fire at a global scale—to the detriment of human society, biodiversity, and ecosystems. These changes pose a global challenge for understanding how to sustain biodiversity in a new era of fire. We synthesize how changes in fire activity are threatening species with extinction across the globe, highlight forward-looking methods for predicting the combined effects of human drivers and fire on biodiversity, and foreshadow emerging actions and strategies that could revolutionize how society manages fire for biodiversity in the Anthropocene. ADVANCES Our synthesis shows that interactions with anthropogenic drivers such as global climate change, land use, and biotic invasions are transforming fire activity and its impacts on biodiversity. More than 4400 terrestrial and freshwater species from a wide range of taxa and habitats face threats associated with modified fire regimes. Many species are threatened by an increase in fire frequency or intensity, but exclusion of fire in ecosystems that need it can also be harmful. The prominent role of human activity in shaping global ecosystems is the hallmark of the Anthropocene and sets the context in which models and actions must be developed. Advances in predictive modeling deliver new opportunities to couple fire and biodiversity data and to link them with forecasts of multiple drivers including drought, invasive plants, and urban growth. Making these connections also provides an opportunity for new actions that could revolutionize how society manages fire. Emerging actions include reintroduction of mammals that reduce fuels, green fire breaks comprising low-flammability plants, strategically letting wildfires burn under the right conditions, managed evolution of populations aided by new genomics tools, and deployment of rapid response teams to protect biodiversity assets. Indigenous fire stewardship and reinstatement of cultural burning in a modern context will enhance biodiversity and human well-being in many regions of the world. At the same time, international efforts to reduce greenhouse gas emissions are crucial to reduce the risk of extreme fire events that contribute to declines in biodiversity. OUTLOOK Conservation of Earth’s biological diversity will be achieved only by recognition of and response to the critical role of fire in shaping ecosystems. Global changes in fire regimes will continue to amplify interactions between anthropogenic drivers and create difficult trade-offs between environmental and social objectives. Scientific input will be crucial for navigating major decisions about novel and changing ecosystems. Strategic collection of data on fire, biodiversity, and socioeconomic variables will be essential for developing models to capture the feedbacks, tipping points, and regime shifts characteristic of the Anthropocene. New partnerships are also needed to meet the challenges ahead. At the local and regional scale, getting more of the “right” type of fire in landscapes that need it requires new alliances and networks to build and apply knowledge. At the national and global scale, biodiversity conservation will benefit from greater integration of fire into national biodiversity strategies and action plans and in the implementation of international agreements and initiatives such as the UN Convention on Biological Diversity. Placing the increasingly important role of people at the forefront of efforts to understand and adapt to changes in fire regimes is central to these endeavors.PostprintPeer reviewe

How global bioeconomy policies and local fire management drive Mediterranean forest landscapes and their associated fire regimes

Europe's bioeconomy policy seeks to diversify the energy sources for industrial purposes through the gradual replacement of fossil fuels by the sustainable use of renewable biological resources (e.g. forest products), and therefore, to contribute to the mitigation of ongoing climate change. Sustainable harvesting levels of forest biomass to meet future demands of bioenergy and wood-based products need to be carefully evaluated, in order to minimize the potential negative impacts of forest exploitation/use on forest ecosystem functioning (and services provisioning) and on their associated biodiversity values. In this study we explore the effects of three European-level bioeconomy scenarios on the coverage of Mediterranean forests, their spatial distribution, and the fire regime (fire frequency and fire size) in Catalonia, a Mediterranean fire-prone region currently dominated by an agro-forest mosaic. The 'Business-as-usual' scenario assumes that no new bioeconomy policies are implemented, the 'EU bioenergy' scenario aims to reduce greenhouse gas emissions in EU28 by increasing bioenergy production, and the 'Global bioeconomy' scenario seeks to enhance a full development of bioeconomy based on bioenergy and the use of biomaterials. We first downscaled to the study region the outputs of GLOBIOM model, a global market equilibrium model that analyzes the competition for land use between the agriculture, forestry, and bioenergy sectors. It generates national-level demands for industrial roundwood and biomass for energy production. We link the outputs of the GLOBIOM to the MEDFIRE model. The MEDFIRE is a regional spatially explicit landscape dynamic model that accounts for vegetation growth, drought-induced mortality, establishment after fire, and afforestation. It incorporates a forest management and land-use change module, and also simulates fire behaviour and fire suppression actions. The combination of the two models allow us to obtain future spatially explicit projections of the Mediterranean forests distribution and coverage on an annual basis from 2010 to 2100, under each bioeconomy scenario. Results show that fire regime is progressively altered, both fire frequency and fire size will increase, in both bioenergy based scenarios due to a positive feedback between more fuel load availability and more severe climate. However, an increase on fire incidence reshape forest structure and compromise future wood demand to meet the bioenergy policies. Scenario projections will be further used to evaluate the potential impacts of each bioeconomy scenario on the provision of ecosystem services linked to Mediterranean forests, as well as their potential effects on biodiversity values. The work presented here is part of the Sumforest project FutureBioEcon.peerReviewe