Extreme wildfire events in recent years are shaking our established knowledge of how fire regimes respond to climate variables and how societies need to react to fire impacts. Albeit fires are ...stochastic and extreme in nature, the speed, intensity, and extension of new extreme fires that have occurred during the last years are unprecedented. Here, we identify common features of these emerging novel extreme wildfire events characterized by very high fire intensity and rapid rates of spread, and we review the major mechanisms behind their occurrence. We then point to the major challenges that extreme wildfire events pose to science and societies worldwide, both today and in the future. Climate change and other factors are contributing to more flammable landscapes and the promotion of unstable atmospheric conditions that ultimately promote wildfire development. Anticipating these novel conditions is a key scientific challenge with paramount implications for present and future fire management, ecosystems, and human well-being.
Context
Forest landscapes worldwide are shaped by abiotic drivers such as fire, windstorms, and drought, but also by biotic drivers like insect pests and pathogens. Although the effects of such ...drivers on forest dynamics have been studied extensively, knowledge of the interactions between insect pests and other drivers of change is still coarse and fragmented. Indeed, new invasive insect species and global change may lead to novel interactions and produce impacts on forest ecosystems never before experienced.
Objectives
We aimed to review the mechanisms underlying interactions between insect pest outbreaks and other forest disturbances, identify interactions emerging from current disturbance dynamics, and highlight the role of simulation models in exploring these interactions in a dynamic, mechanistic, and spatially explicit manner.
Methods
We reviewed the state of the science regarding interactions between insect pests and other forest disturbances, collecting a set of 216 scientific articles.
Results
Most studies focused on the interaction between insect outbreaks and fire, whereas interactions between insect pests and drought, forest management or forest diseases received much less attention. Although we identified some trends in how interactions were manifested, interactions were not more commonly found at particular spatial or temporal scales. Relatively few studies used simulation models to explore interactions between disturbances and very few studies explored multiple interactions.
Conclusions
Interactions between pests and other forest disturbances play critical roles in driving forest dynamics. The effects of these interactions are likely to increase in the face of continuing global change.
In densely populated fire-prone regions, interactions between global change drivers, such as landcover changes and climate change, may increase the frequency and severity of wildfires impacting ...forest ecosystems, thus diminishing their capability of provisioning key ecosystem goods and services for these societies. Yet, landscape mosaics play a crucial role in fire dynamics and behaviour. Here, we argue that promoting heterogeneous agro-forest mosaics could reduce the area affected by future fires. Specifically, we evaluated 24 landscape-scale management scenarios based on agricultural conversion, i.e. the creation of new agricultural land, that also explicitly incorporated fire suppression. Scenarios differed in the annual rate of such conversion, the spatial pattern (aggregate vs. scattered), and the location of new agricultural patches. To quantify the interactions between vegetation dynamics, fires, land-cover changes, and fire suppression, we coupled two spatially explicit models: a landscape dynamic fire-succession model and a land-cover change model. When applied to the Mediterranean region of Catalonia (NE Spain), new landscape mosaics favoured firefighting extinction capacity only after 15 years (on average) of cumulative land transformations. Agricultural conversion of at least 100 km² year⁻¹ was required to reduce total area burnt. A conversion rate of 200 km² year⁻¹ substantially improved fire suppression effectiveness, but subsequent conversion increases did not. When aggregated, new agriculture patches contributed more effectively to reduction in total area burnt and decreased the edge effect on remaining forest patches. Agricultural conversion in Mediterranean landscapes opens a new window for long-term spatial planning aimed at minimizing negative impacts of wildfire on forest ecosystems. These alternative strategies could help to develop landscape management practices in other fire-prone regions.
Exploring new approaches and methodologies to characterize species distribution dynamics, instead of solely relying on static spatial patterns, should be a priority for species distribution modelling ...research. Dynamic occupancy models (here, ‘dynocc models') are a promising tool to capture temporal patterns of distribution change but their spatial accuracy has been shown to be limited. In this study, we evaluated the effectiveness of incorporating neighborhood connectivity effects into the colonization and extinction functions of dynocc models. To accomplish this, we compared dynocc models accounting either for neighborhood connectivity only, for site‐level habitat covariates only, or combining both neighborhood and habitat explanations in the models for species extinction and colonization. All models were evaluated for a total of 46 bird species typical of forests and shrublands using data at 1 km2 scale from two Catalan breeding bird atlases (CBBA2: 1999–2002 and CBBA3: 2015–2018). Models' predictive performance varied across species between dynocc models incorporating habitat covariates alone and those considering neighborhood connectivity alone. Among species, 68% exhibited a predominant response to habitat effects, 24% showed similar responses for habitat and connectivity effects, and 9% were mostly associated with connectivity effects. Dynocc models combining connectivity and habitat covariates achieved the best predictive performance for most species, with bigger gains for species with similar results from habitat‐only and connectivity‐only models. However, relative performance gains compared to dynocc models using only habitat or connectivity variables were generally modest for most species. This study shows the benefits of considering more spatially explicit formulations in dynocc models, specifically incorporating neighborhood connectivity into the extinction and colonization processes. Our work also highlights the importance of evaluating different model formulations and assessing which aspects of the model are more important depending on the study species.
Context
Seed dispersal by birds plays a crucial role in structuring landscape dynamics. The dispersal process has been extensively studied at local scales; however, landscape scale approaches are ...scarce. The wide availability of bird species distribution data can be used to explore plant dispersal processes at large spatial scales.
Objective
We investigated whether and at which scale bird-seed-dispersal indicators (BSDI) based on species distribution models (SDMs), together with climatic and landscape structure metrics related to habitat preferences of birds, aid the explanation of the distribution of
Viscum album
.
Methods
We developed a set of BSDI (
abundance
,
species richness
,
Turdus
spp.
richness
, and
specialization
) at four different scales (500–3500 m). They served as predictors, along with other environmental variables, in generalized linear models to predict
V. album
distribution in Catalonia, Spain.
Results
The indicator
Turdus
spp.
richness
(3500 m) explained up to 15% of variance. This contribution was smaller when it was considered alongside other predictors, where climatic conditions and % of olive groves explained ca. 35% and 13% variance, respectively. The
abundance
or
species richness
BSDI proved to be poor predictors of
V. album
distribution.
Conclusions
We demonstrated the functionality of BSDI based on SDMs to predict the distribution of
V. album
and the importance to test them at different spatial scales. BSDI showed a clear larger effect with increasing scale, suggesting a strong link between the mobility of birds and the plant dispersal process. The modelling approach could be applied to different localities and species to understand plant seed dispersal at landscape scale.
1. It has been argued that wildfires are one of the major agents involved in landscape transformation in many European regions and their impact is expected to increase in the near future. Despite the ...recognized impact of fire on wildlife at a local scale, we lack information on the species responses to fire at larger spatial scales. 2. In this study, we used the ortolan bunting Emberiza hortulana to evaluate the potential effects of wildfires on open-habitat species distribution. In contrast to most European countries, this farmland species has experienced a consistent range expansion during the last decades in Catalonia (northeast Iberian peninsula). Distribution data of the species collected at different time periods allowed us to test the role of fires in determining range expansions at a regional scale, and to evaluate the importance of dispersal constraints on distribution changes. 3. Analyses of distribution data from 1975-1983 and 1999-2002 showed a consistent expansion of the ortolan bunting in Catalonia. After correcting for differences in sampling effort, changes in distribution showed a strong spatial pattern with colonization and stability, but not local extinction, being clumped in space. Patterns of change were also strongly and significantly associated with the amount of shrubland burnt between the two time periods, since areas that experienced a larger impact of fires in terms of burnt area showed a much higher probability of maintaining species presence or of being colonized. Colonization events appeared to be more likely in areas affected by fire especially when surrounding areas had already been colonized by the species. 4. Synthesis and applications. Overall, our results support the hypothesis that wildfires, especially those affecting open woodlands or shrubby areas, play a critical role in the ecology of the ortolan bunting and have contributed to the recent expansion of the species in Catalonia. Furthermore, we have shown that colonization appears to be limited, not only by the availability of new burnt habitat but also by specific dispersal constraints. We suggest that, for several European threatened species associated with open habitats, burnt areas may partially compensate for the widespread loss and deterioration of farmland habitat, opening new management opportunities for their conservation.
Processes derived from global change such as land-use changes, climate warming or modifications in the perturbation regime may have opposite effects on forest extent and structure with still unknown ...consequences on forest biodiversity at large spatial scales. In the present study, we aimed at determining forest dynamics associated with global change processes (forest spread, maturation and fire) that have driven the variation in forest bird distributions in Mediterranean forest ecosystems in recent years. The study was located in Catalonia (NE Spain) and used changes in richness of specialist and generalist forest bird species in the last 20 years of the 20th century as indicators of forest biodiversity change. Forest bird distribution changes showed strong spatial patterns and appeared to be related to population processes occurring beyond sampling units (10 km x 10 km squares). Forest maturation appeared as the most important driver of such changes because most of the studied species have a non-Mediterranean origin and are associated with more mature forests. To a lower degree, forest spread also contributed to forest bird distribution changes whereas the impact of forest fires was not associated to a decrease in the richness of either group of forest species. Given the relatively coarse scale at which our study was conducted, caution should be taken when extrapolating our results to the possible future impacts of climate change on fire regime and forest bird distribution. Our results indicate that large-scale forest maturation and spread due mainly to land abandonment in Catalonia has overridden the potentially negative effects of fires on forest bird distributions and are currently driving changes in forest biodiversity patterns across the region.
•We distinguished 6 synoptic weather types leading to large wildfires in Catalonia.•Three types were defined by wind, and two types involved hot and dry environments.•South intrusion triggered the ...larger number of fires and burned area in the region.•Different spatial distributions emerged from the influence of each situation.•Fire suppression managed to reduce fires in heat situations, but not in windy ones.
Analysis of global change effects on fire regimes requires evaluations of key processes explaining fire activity at the appropriate spatial and temporal scales. Classifications of the weather conditions prevailing at large continental scales (called “Synoptic Weather Types”, SWT) offer convenient potential proxies for integrating weather-related factors into our understanding of fire regime attributes at regional scales. Here we establish a methodology for identifying the major SWT that lead to wildfires and assessing their influence on fire regime in interaction with other global drivers such as drought events or fire suppression policies. Based on days with fires larger than 50 ha that occurred in Catalonia, a region located in the western Mediterranean Basin, we propose a clustering methodology using data of temperature at 850 hPa, sea level pressure and winds at 925 hPa from the NCEP/NCAR reanalysis dataset covering the whole of western Europe (25–70°N and 20°W–40°E). Our classification method proposes 6 SWT: three that were characterized by synoptic conditions leading to strong winds in the region, two that led to ‘hot and dry’ environments, and one that was not characterized by any strong weather determinants. Fires under ‘hot and dry’ conditions, such as the South intrusion SWT, triggered the bulk of fires and burnt area in the region. Spatial analyses of fire distribution under each SWT revealed markedly different fire-prone locations, opening the possibility for strategic planning of fire management based on local fire regimes. Fires occurring during mild years (wet spring conditions) and under ‘hot-and-dry’ SWTs have been eradicated from the region thanks to enhanced firefighting capability, and fire sizes in dry years have strongly reduced. In contrast, fires occurring under windy situations have not followed the same course of change and have not diminished in incidence over time, and seem to be more difficult to control using current fire suppression strategies. The role of SWT on determining fire regimes and its interaction with fire suppression strategies has a huge potential to help researchers and managers develop better fire analyses based on sound physical grounds and serve to understand and eventually regulate the adverse impacts of fire regime changes in a global change context.
Rapid behavioural response of urban birds to COVID-19 lockdown Gordo, Oscar; Brotons, Lluís; Herrando, Sergi ...
Proceedings - Royal Society. Biological sciences/Proceedings - Royal Society. Biological Sciences,
03/2021, Letnik:
288, Številka:
1946
Journal Article
Recenzirano
Odprti dostop
Biodiversity is threatened by the growth of urban areas. However, it is still poorly understood how animals can cope with and adapt to these rapid and dramatic transformations of natural ...environments. The COVID-19 pandemic provides us with a unique opportunity to unveil the mechanisms involved in this process. Lockdown measures imposed in most countries are causing an unprecedented reduction of human activities, giving us an experimental setting to assess the effects of our lifestyle on biodiversity. We studied the birds' response to the population lockdown by using more than 126 000 bird records collected by a citizen science project in northeastern Spain. We compared the occurrence and detectability of birds during the spring 2020 lockdown with baseline data from previous years in the same urban areas and dates. We found that birds did not increase their probability of occurrence in urban areas during the lockdown, refuting the hypothesis that nature has recovered its space in human-emptied urban areas. However, we found an increase in bird detectability, especially during early morning, suggesting a rapid change in the birds' daily routines in response to quieter and less crowded cities. Therefore, urban birds show high behavioural plasticity to rapidly adjust to novel environmental conditions, such as those imposed by the COVID-19.
Increasing landscape heterogeneity by restoring semi‐natural elements to reverse farmland biodiversity declines is not always economically feasible or acceptable to farmers due to competition for ...land. We hypothesized that increasing the heterogeneity of the crop mosaic itself, hereafter referred to as crop heterogeneity, can have beneficial effects on within‐field plant diversity.
Using a unique multi‐country dataset from a cross‐continent collaborative project covering 1,451 agricultural fields within 432 landscapes in Europe and Canada, we assessed the relative effects of compositional and configurational crop heterogeneity on within‐field plant diversity components. We also examined how these relationships were modulated by the position within the field.
We found strong positive effects of configurational crop heterogeneity on within‐field plant alpha and gamma diversity in field interiors. These effects were as high as the effect of semi‐natural cover. In field borders, effects of crop heterogeneity were limited to alpha diversity. We suggest that a heterogeneous crop mosaic may overcome the high negative impact of management practices on plant diversity in field interiors, whereas in field borders, where plant diversity is already high, landscape effects are more limited.
Synthesis and applications. Our study shows that increasing configurational crop heterogeneity is beneficial to within‐field plant diversity. It opens up a new effective and complementary way to promote farmland biodiversity without taking land out of agricultural production. We therefore recommend adopting manipulation of crop heterogeneity as a specific, effective management option in future policy measures, perhaps adding to agri‐environment schemes, to contribute to the conservation of farmland plant diversity.
Résumé
Accroître l’hétérogénéité du paysage en restaurant les éléments semi‐naturels pour enrayer le déclin de la biodiversité agricole n’est pas toujours économiquement faisable ou socialement acceptable pour les agriculteurs étant donné la compétition pour les terres. Nous faisons l’hypothèse qu’accroître l’hétérogénéité de la mosaïque de cultures, ci‐après désignée par l’hétérogénéité des cultures, peut aussi avoir des effets bénéfiques sur la diversité des plantes au sein des parcelles.
Par l’utilisation d’un jeu de données multi‐pays issu d’un projet collaboratif trans‐continental rassemblant 1451 parcelles agricoles distribuées dans 432 paysages d’Europe et du Canada, nous avons estimé les effets de la composition et la configuration de l’hétérogénéité des cultures sur les composantes de la diversité des plantes au sein des parcelles.
Nous avons mis en évidence un fort effet positif de l’hétérogénéité de configuration des cultures sur la diversité alpha et beta des plantes, à l’intérieur des parcelles. Ces effets sont aussi importants que l’effet des éléments semi‐naturels. Au niveau des bords de champs, l’effet de l’hétérogénéité des cultures se limite à la diversité alpha. Nous suggérons qu’une mosaïque de cultures hétérogène peut atténuer l’effet négatif des pratiques de gestion sur la diversité des plantes à l’intérieur des parcelles, tandis qu’au niveau des bords de champs, où la diversité en plantes est plus élevée, les effets du paysage sont plus limités.
Synthèse et applications. Notre étude montre qu’accroître l’hétérogénéité de configuration des cultures est bénéfique pour la diversité des plantes au sein des parcelles. Elle ouvre de nouvelles perspectives quant au maintien et à la restauration de la biodiversité agricole sans empiéter sur les surfaces de production agricole. C’est pourquoi nous recommandons de considérer la manipulation de l’hétérogénéité des cultures dans l’élaboration des mesures politiques, en complément des mesures agri‐environnementales, pour contribuer à la conservation de la diversité des plantes en milieu agricole.
Our study shows that increasing configurational crop heterogeneity is beneficial to within‐field plant diversity. It opens up a new effective and complementary way to promote farmland biodiversity without taking land out of agricultural production. We therefore recommend adopting manipulation of crop heterogeneity as a specific, effective management option in future policy measures, perhaps adding to agri‐environment schemes, to contribute to the conservation of farmland plant diversity.
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