Compound fire-drought regimes promote ecosystem transitions in Mediterranean ecosystems

Batllori E., De Cáceres M., Brotons L., Ackerly D.D., Moritz M.A., Lloret F. (2019) Compound fire-drought regimes promote ecosystem transitions in Mediterranean ecosystems. Journal of Ecology. 107: 1187-1198.
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Doi: 10.1111/1365-2745.13115

Resumen:

Understanding ecosystem responses to compound disturbance regimes and the influence of specific sequences of events in determining ecosystem shifts remains a challenge. We use a modelling framework for Mediterranean-type ecosystems to assess the effects of fire–drought interactions on long-term vegetation dynamics and to identify disturbance-driven changes in trait composition (tree seeder vs. tree resprouter prevalence) and ecosystem state (forest vs. non-forest). Changes in tree seeder and the tree resprouter dominance show nonlinear, threshold-type trends over gradients of increasing compound disturbance frequency. Vegetation composition thresholds mostly occur in a narrow range of the compound fire–drought disturbance space. Additionally, trait compositional switches and the likelihood of sudden changes in ecosystem state are promoted by fire-drought interactions. Distinct sequences of disturbance events cause vegetation transitions, disrupting ecosystem resilience, even under moderate recurrence of individual disturbances. An extreme drought year followed by one or two large fire events promotes shifts from resprouter- to seeder dominance. Contrastingly, a large crown fire followed by an extreme drought promotes changes from seeder to resprouter dominance. This disturbance sequence is also a mechanism strong enough to trigger sudden shifts in ecosystem state (from forest to non-forest). Synthesis. Thresholds of change in vegetation composition occur over a narrow range of the modelled gradients of compound fire-drought recurrence, and the loss of ecosystem resilience is contingent on particular sequences of disturbance events. Overall, our findings highlight that disturbance interactions define the relative location of tipping points in ecosystem state, and that effects and feedbacks of compound disturbance regimes increase the long-term likelihood of sudden ecosystem shifts and, therefore, uncertainty in predicting vegetation state. © 2018 The Authors. Journal of Ecology © 2018 British Ecological Society

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How can climate change affect the potential distribution of common genet Genetta genetta (Linnaeus 1758) in Europe?

Camps D., Villero D., Ruiz-Olmo J., Brotons L. (2019) How can climate change affect the potential distribution of common genet Genetta genetta (Linnaeus 1758) in Europe?. Mammal Research. 64: 175-182.
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Doi: 10.1007/s13364-018-0399-4

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The common genet Genetta genetta is a carnivore of African origin introduced in Europe at least 13 centuries ago. Its distribution, located in the southwest of the continent, is chiefly constrained by climatic factors. With this premise, and taking into account the existing climate change projections, our goal was to assess possible changes in climatic suitability for common genet in Europe in the future. The maximum entropy statistical method was used to evaluate the potential effects of two greenhouse gas scenarios-low and high emissions-of an average ensemble of six different global circulation models. Projections showed that a large increase in climatically suitable habitat for common genet in continental Europe is likely in the next decades. In this way, the species range may expand within Europe to the east and north. The fact that the common genet may be favoured in a scenario of temperature increase is compatible with the origin of the species associated with hotter climates in Africa. However, despite these results, bioclimatic models do not represent the complete biotic and ecological niche of the species (e.g. competition, predation or dispersal ability), and a full understanding of potential future expansions should include factors that also determine the presence of the species at finer local scales. Bearing this in mind, we have to interpret our results as a first step towards the potential for species distribution change in the near future, but further work should incorporate environmental variability beyond climate in future projection assessments. © 2018, Mammal Research Institute, Polish Academy of Sciences, Białowieża, Poland.

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Quantifying pine processionary moth defoliation in a pine-oak mixed forest using unmanned aerial systems and multispectral imagery

Cardil A., Otsu K., Pla M., Silva C.A., Brotons L. (2019) Quantifying pine processionary moth defoliation in a pine-oak mixed forest using unmanned aerial systems and multispectral imagery. PLoS ONE. 14: 0-0.
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Doi: 10.1371/journal.pone.0213027

Resumen:

Pine processionary moth (PPM) feeds on conifer foliage and periodically result in outbreaks leading to large scale defoliation, causing decreased tree growth, vitality and tree reproduction capacity. Multispectral high-resolution imagery acquired from a UAS platform was successfully used to assess pest tree damage at the tree level in a pine-oak mixed forest. We generated point clouds and multispectral orthomosaics from UAS through photogrammetric processes. These were used to automatically delineate individual tree crowns and calculate vegetation indices such as the normalized difference vegetation index (NDVI) and excess green index (ExG) to objectively quantify defoliation of trees previously identified. Overall, our research suggests that UAS imagery and its derived products enable robust estimation of tree crowns with acceptable accuracy and the assessment of tree defoliation by classifying trees along a gradient from completely defoliated to non-defoliated automatically with 81.8% overall accuracy. The promising results presented in this work should inspire further research and applications involving a combination of methods allowing the scaling up of the results on multispectral imagery by integrating satellite remote sensing information in the assessments over large spatial scales. © 2019 Cardil et al. This is an open access article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited.

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Adapting prescribed burns to future climate change in Mediterranean landscapes

Duane A., Aquilué N., Canelles Q., Morán-Ordoñez A., De Cáceres M., Brotons L. (2019) Adapting prescribed burns to future climate change in Mediterranean landscapes. Science of the Total Environment. 677: 68-83.
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Doi: 10.1016/j.scitotenv.2019.04.348

Resumen:

Fire regimes are shifting or are expected to do so under global change. Current fire suppression is not able to control all wildfires, and its capability to do so might be compromised under harsher climate conditions. Alternative fire management strategies may allow to counteract predicted fire trends, but we lack quantitative tools to evaluate their potential effectiveness at the landscape scale. Here, we sought to quantify changes in fire regimes induced after the implementation of different fire management strategies. We developed and applied a new version of the model MEDFIRE in Catalonia (Mediterranean region of ~32,000 km 2 in NE Spain). We first projected burnt area from 2016 to 2100 resulting from climate change under the Representative Concentration Pathway 8.5 scenario of HadGEM-CC model and under current fire suppression levels. We then evaluated the impacts of four fire management strategies: ‘Let it burn’, fixed effort of prescribed burning with two different spatial allocations, and adaptive prescribed burning dynamically adjusting efforts according to recent past fires. Results predicted the emergence of novel climates associated with similar barometric configurations to current conditions but with higher temperatures (i.e. hot wind events). These novel climates led to an increase in burnt area, which was partially counteracted by negative fire-vegetation feedbacks. All prescribed burning scenarios decreased the amount of high-intensity fires and extreme fire events. The ‘Let it burn’ strategy, although less costly, was not able to reduce the extent of high-intensity fires. The adaptive prescribed burning scenario resulted in the most cost-efficient strategy. Our results provide quantitative evidence of fire management effectiveness, and bring to light key insights that could guide the design of fire policies fit for future novel climate conditions. We propose adaptive landscape management focused on the reduction of fire negative impacts rather than on the elimination of this disturbance from the system. © 2019 Elsevier B.V.

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A quantitative assessment of mid-term risks of global change on forests in Western Mediterranean Europe

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.
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Doi: 10.1007/s10113-018-1437-0

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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.

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A dynamic strategy for EU conservation

Hermoso V., Morán-Ordóñez A., Canessa S., Brotons L. (2019) A dynamic strategy for EU conservation. Science. 363: 592-593.
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Doi: 10.1126/science.aaw3615

Resumen:

[No abstract available]

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Contrasting impacts of precipitation on Mediterranean birds and butterflies

Herrando S., Titeux N., Brotons L., Anton M., Ubach A., Villero D., García-Barros E., Munguira M.L., Godinho C., Stefanescu C. (2019) Contrasting impacts of precipitation on Mediterranean birds and butterflies. Scientific Reports. 9: 0-0.
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Doi: 10.1038/s41598-019-42171-4

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The climatic preferences of the species determine to a large extent their response to climate change. Temperature preferences have been shown to play a key role in driving trends in animal populations. However, the relative importance of temperature and precipitation preferences is still poorly understood, particularly in systems where ecological processes are strongly constrained by the amount and timing of rainfall. In this study, we estimated the role played by temperature and precipitation preferences in determining population trends for birds and butterflies in a Mediterranean area. Trends were derived from long-term biodiversity monitoring data and temperature and precipitation preferences were estimated from species distribution data at three different geographical scales. We show that population trends were first and foremost related to precipitation preferences both in birds and in butterflies. Temperature preferences had a weaker effect on population trends, and were significant only in birds. The effect of precipitation on population trends operated in opposite directions in the two groups of species: butterfly species from arid environments and bird species from humid habitats are decreasing most. Our results indicate that, although commonly neglected, water availability is likely an important driver of animal population change in the Mediterranean region, with highly contrasting impacts among taxonomical groups. © 2019, The Author(s).

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Designing a network of green infrastructure to enhance the conservation value of protected areas and maintain ecosystem services

Lanzas M., Hermoso V., de-Miguel S., Bota G., Brotons L. (2019) Designing a network of green infrastructure to enhance the conservation value of protected areas and maintain ecosystem services. Science of the Total Environment. 651: 541-550.
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Doi: 10.1016/j.scitotenv.2018.09.164

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There is a growing demand for holistic landscape planning to enhance sustainable use of ecosystem services (ESS) and maintenance of the biodiversity that supports them. In this context, the EU is developing policy to regulate the maintenance of ESS and enhance connectivity among protected areas (PAs). This is known as the network of Green Infrastructure (GI). However, there is not a working framework defined to plan the spatial design of such network of GI. Here, we use the software Marxan with Zones, to prioritize the spatial distribution of different management zones that accommodate the needs of a network of GI. These zones included a conservation zone, mainly devoted to protecting biodiversity, a GI zone, that aimed at connecting PAs and maintaining regulating and cultural ESS; and a management zone devoted to exploiting provisioning ESS. We performed four planning scenarios that distribute the targets for ESS and biodiversity in different ways across management zones. We also conducted a sensitivity analysis by increasing ESS targets to explore trade-offs that may occur when managing together biodiversity and ESS. We use Catalonia (northeastern Spain) as a case study. We found that the representation of ESS could be achieved for intermediate targets in all scenarios. There was, however, a threshold on these targets over which trade-offs appeared between maintaining regulating and cultural ESS and biodiversity versus getting access to provisioning ESS. These “thresholds values” were displaced towards higher ESS targets when we moved from more strict to more flexible planning scenarios (i.e., scenarios that allowed mixing representation of objectives for biodiversity and ESS within the same zone). This methodological approach could help design a framework to integrate biodiversity and ESS management in holistic plans and decision making and, at the same time, meeting European mandates concerning the design of GI networks, or similar needs elsewhere. © 2018 Elsevier B.V.

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Declining population trends of European mountain birds

Lehikoinen A., Brotons L., Calladine J., Campedelli T., Escandell V., Flousek J., Grueneberg C., Haas F., Harris S., Herrando S., Husby M., Jiguet F., Kålås J.A., Lindström Å., Lorrillière R., Molina B., Pladevall C., Calvi G., Sattler T., Schmid H., Sirkiä P.M., Teufelbauer N., Trautmann S. (2019) Declining population trends of European mountain birds. Global Change Biology. 25: 577-588.
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Doi: 10.1111/gcb.14522

Resumen:

Mountain areas often hold special species communities, and they are high on the list of conservation concern. Global warming and changes in human land use, such as grazing pressure and afforestation, have been suggested to be major threats for biodiversity in the mountain areas, affecting species abundance and causing distribution shifts towards mountaintops. Population shifts towards poles and mountaintops have been documented in several areas, indicating that climate change is one of the key drivers of species’ distribution changes. Despite the high conservation concern, relatively little is known about the population trends of species in mountain areas due to low accessibility and difficult working conditions. Thanks to the recent improvement of bird monitoring schemes around Europe, we can here report a first account of population trends of 44 bird species from four major European mountain regions: Fennoscandia, UK upland, south-western (Iberia) and south-central mountains (Alps), covering 12 countries. Overall, the mountain bird species declined significantly (−7%) during 2002–2014, which is similar to the declining rate in common birds in Europe during the same period. Mountain specialists showed a significant −10% decline in population numbers. The slope for mountain generalists was also negative, but not significantly so. The slopes of specialists and generalists did not differ from each other. Fennoscandian and Iberian populations were on average declining, while in United Kingdom and Alps, trends were nonsignificant. Temperature change or migratory behaviour was not significantly associated with regional population trends of species. Alpine habitats are highly vulnerable to climate change, and this is certainly one of the main drivers of mountain bird population trends. However, observed declines can also be partly linked with local land use practices. More efforts should be undertaken to identify the causes of decline and to increase conservation efforts for these populations. © 2018 John Wiley & Sons Ltd

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Building on Margalef: Testing the links between landscape structure, energy and information flows driven by farming and biodiversity

Marull J., Herrando S., Brotons L., Melero Y., Pino J., Cattaneo C., Pons M., Llobet J., Tello E. (2019) Building on Margalef: Testing the links between landscape structure, energy and information flows driven by farming and biodiversity. Science of the Total Environment. 674: 603-614.
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Doi: 10.1016/j.scitotenv.2019.04.129

Resumen:

The aim of this paper is to test two methodologies, applicable to different spatial scales (from regional to local), to predict the capacity of agroecosystems to provide habitats for the species richness of butterflies and birds, based on the ways their socio-metabolic flows change the ecological functionality of bio-cultural landscapes. First, we use the more general Intermediate Disturbance-Complexity (IDC) model to assess how different levels of human appropriation of photosynthetic production affect the landscape functional structure that hosts biodiversity. Second, we apply a more detailed Energy-Landscape Integrated Analysis (ELIA) model that focusses on the energy storage carried out by the internal biomass loops, and the energy information held in the network of energy flows driven by farmers, in order to correlate both (the energy reinvested and redistributed) with the energy imprinted in the landscape patterns and processes that sustain biodiversity. The results obtained after applying both models in the province and the metropolitan region of Barcelona support the Margalef's energy-information-structure hypothesis by showing positive relations between butterflies' species richness, IDC and ELIA, and between birds' species richness and energy information. Our findings support the view that strong relationships between farming energy flows, agroecosystem functioning and biodiversity can be detected, and highlight the importance of farmers' knowledge and labour to maintain bio-cultural landscapes. © 2019 Elsevier B.V.

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