Philosophical Transactions of the Royal Society B: Biological Sciences最新文献

Ecological effects of changing fire regimes are well documented for plant and animal populations, but less is known about how fire influences, and is influenced by, specialized plant-animal interactions. In this review, we identified mutualistic (pollination, seed dispersal and food provision), commensal (habitat provision) and antagonistic (seed predation, herbivory and parasitism) plant-animal interactions from fire-prone ecosystems. We focused on specialized interactions where a single genus depended on one to two genera in a single family of plant or animal. We categorized the plant partner's post-fire reproductive mode to assess the likely outcome of changing fire regimes on ecological functions provided by these interactions. Traits underlying specialization in fire-prone ecosystems for plants were: post-fire reproductive mode, time to maturity, morphology and phenology; and, for animals: dispersal, specialized organs, nesting and egg deposition substrates, plant consumption behaviours and pollinator behaviours. Finally, we identified a number of cases where stabilizing feedbacks maintained plant-animal interactions under natural fire regimes. Potential reinforcing feedbacks were also identified, but were more likely to happen abruptly and result in collapse of the plant-animal partnership, or partner switching. Our synthesis reveals how fire regime changes impact fire-dependent specialist plant-animal interactions and potentially drive eco-evolutionary dynamics in fire-prone ecosystems globally.This article is part of the theme issue 'Novel fire regimes under climate changes and human influences: impacts, ecosystem responses and feedbacks'.

A spread day is defined as a day in which fires grow by a substantial amount of area, usually during high or extreme fire weather conditions. Accurately identifying a spread day under various environmental conditions could help both our understanding of fire regimes and with forecasting and managing fires on the ground. Although spread days could occur within a spectrum of fire weather conditions, a threshold is important to fire management and fire research. This study explores the relationships between spread days and fire activity in the forested area of Canada by spatially and temporally matching daily fire growth to interpolated daily gridded fire weather between 2001 and 2021. Using accumulative area burned density functions, we identified the fire weather conditions for spread days by Canadian Ecozones both annually and seasonally. Using these identifiers as thresholds, we estimated how extreme fire weather needs to be for a spread day to occur, and the proportions of potential spread days (PSDs) that would most likely be realized in real fire spread at various Canadian Ecozones. Our results showed that the median-level fire-conducive weather conditions are sufficient to support active fire growth, and on average, about 22-30% of such days may be realized in real fire spread at various Canadian Ecozones.This article is part of the theme issue 'Novel fire regimes under climate changes and human influences: impacts, ecosystem responses and feedbacks'.

Smoke and particulate matter released from forest fires, affecting the photosynthetic rate and stomatal conductance, may change the isotope composition in tree rings. Therefore, analysis of tree-ring isotopes could be a promising approach to monitor fires. We hypothesized that forest fires could influence the abundance of carbon (δ¹³C), oxygen (δ¹⁸O) and nitrogen (δ¹⁵N) isotopes and the radial growth of tree rings of conifers through their impact on the physiological processes. We collected wood cores from four coniferous species in northern and southern China. The isotope composition of these samples was analysed to shed light on the correlation between fire occurrence and tree-ring isotopes. We found that fires led to an increase in δ¹³C but a decrease in δ¹⁵N in the whole wood, while significant increases of above 0.5‰ in δ¹³C and a decrease of 0.2 to 0.5‰ in δ¹⁸O in the α-cellulose were observed. Meteorological factors including precipitation and relative humidity influenced the isotope abundance. Besides, forest fires inhibited the radial growth of conifer trees, particularly Cryptomeria fortunei. Our results suggest that variations in δ¹³C and δ¹⁸O abundance in tree rings play an essential role as an indicator of forest fire occurrence, providing additional insights into the study of fire history.This article is part of the theme issue 'Novel fire regimes under climate changes and human influences: impacts, ecosystem responses and feedbacks'.

Fire regime refers to the statistical characteristics of fire events within specific spatio-temporal contexts, shaped by interactions among climatic conditions, vegetation types and natural or anthropogenic ignitions. Under the dual pressures of intensified global climate changes and human activities, fire regimes worldwide are undergoing unprecedented transformations, marked by increasing frequency of large and intense wildfires in some regions, yet declining fire activity in others. These fire regime changes (FRC) may drive responses in ecosystem structure and function across spatio-temporal scales, posing significant challenges to socio-economic adaptation and mitigation capacities. To date, research on the patterns and mechanisms of global FRC has rapidly expanded, with investigations into driving factors revealing complex interactions. This review synthesizes research advancements in FRC by analysing 17 articles from this special issue and 249 additional publications retrieved from the Web of Science. We systematically outline the key characteristics of FRC, geographical hotspots of fire regime transformation, critical fire-prone vegetation types, primary climatic and anthropogenic drivers and ecosystem adaptations and feedbacks. Finally, we highlight research frontiers and identify key approaches to advance this field and emphasize an interdisciplinary perspective in understanding and adapting to FRC.This article is part of the theme issue 'Novel fire regimes under climate changes and human influences: impacts, ecosystem responses and feedbacks'.

Fire increasingly conflicts with the built environment. The wildland-urban interface (WUI) describes areas where vegetation near the built environment increases wildfire hazard. In the United States, attention concentrates on WUI in forested areas, but human populations are extending into rangelands. The combination of WUI expansion and woody plant encroachment might present novel challenges to wildfire management, especially given the rural nature of rangelands in the US, which extends the response time of emergency services. We use publicly available data to describe the abundance, distribution, type and overall wildfire risk in rural rangelands. Most of the WUI in the US Interior West (54%) occurs in rangeland: the majority of the US Interior West is rangeland and 4.3% of that-over 1 million km²-is WUI. Most WUI is rural: 59% is further than 10 km from town and tribal areas are even more remote. Rangeland WUI is approximately twice as likely to be degraded by woody encroachment than non-WUI rangeland, suggesting that conventional fire suppression tactics for rangeland fuels might be insufficient or unsafe. Greater awareness of rural rangeland WUI might help leverage community-level adaptive capacity against the novel challenges of protecting lives and property beyond urban/peri-urban zones.This article is part of the theme issue 'Novel fire regimes under climate changes and human influences: impacts, ecosystem responses and feedbacks'.

We aimed at disentangling the role of different local and regional controls influencing fire occurrence in two geographically distinct forest reserves in Finland. We used dendrochronological data to reconstruct fire histories and, using survival analysis, analysed fire occurrence as a function of forest stand (mesic and xeric site type, topographical wetness index) and landscape characteristics (stand area, neighbouring stand identity and shared border length), and the study region. In total, we dated 182 fires between 1574 and 1921. Fires were the most active during 1712-1887, several fires burning up to 10% of the area, and have been absent since the early 1900s. Regardless of the site type, one of the reserves had a higher probability to burn than either site type in the other, showing the importance of larger-scale spatial variation. Also, site type of the neighbouring stand played a role, with a mesic neighbour decreasing the probability of fire in a xeric stand. We highlighted the importance of regional context (e.g. differences in human use of forests) and landscape structure, which may play as a determinant of historical fire regimes.This article is part of the theme issue 'Novel fire regimes under climate changes and human influences: impacts, ecosystem responses and feedbacks'.

Increasingly frequent and severe forest fires, exacerbated by warmer and drier conditions, significantly affect forest ecosystems. Understanding the dynamics of post-fire forest recovery is crucial for assessing forest resilience and guiding forest management. However, most post-fire recovery studies focus primarily on spatial variation, while recovery changes over time are relatively less studied. In this study, we examined the patterns, trends and drivers of spectral recovery from forest fires that burned between 2002 and 2018 in boreal and temperate forests. We used relative recovery indicators (RRIs) developed from three spectral indices-the normalized burn ratio, normalized difference vegetation index and near-infrared reflectance of vegetation-to capture post-fire spectral recovery. Our results showed that post-fire spectral recovery rates in temperate forests are faster than those in boreal forests, with quicker recovery in regions with higher percentages of broad-leaved species, less severe fires, higher temperature and precipitation. The decline in spectral forest recovery rates of boreal forests indicates that boreal forest post-fire recovery is becoming increasingly challenging. Our work provides valuable insights into forest management and conservation in the face of increasing fire frequency and intensity.This article is part of the theme issue 'Novel fire regimes under climate changes and human influences: impacts, ecosystem responses and feedbacks'.

Lack of knowledge of plant flammability has impeded the understanding of ecological feedbacks between fire and vegetation. We measured flammability traits of 263 woody plant species in the subtropical semi-humid regions of China to identify plant flammability strategies and assess the impact of fire frequency on different plant flammability syndromes that were defined as combinations of flammability strategies of leaves and bark. The results indicated that 40.0%, 39.1% and 20.9% of woody plant species had hot-, fast- and low-flammable leaves, respectively, and 28.2%, 35.7% and 36.1% of species had hot-, fast- and low-flammable bark, respectively. Tree species (47.5%) had a higher percentage of flammability strategy separation between leaves and bark than large shrubs (19.7%) and shrub species (18.2%). Community-level evidence showed that species with fast- or hot-flammable leaves and bark may gain a notable advantage with repeated fires. Structural equation models indicated that more frequently burned forests were associated with infertile soil, shrub enrichment and lower species richness, subsequently leading to favour on flammable plant species. Thus, a positive feedback loop would be generated between the dominance of flammable species in the plant communities and fire frequency, fostering the characteristics of fire regimes in the semi-humid evergreen broadleaved forests.This article is part of the theme issue 'Novel fire regimes under climate changes and human influences: impacts, ecosystem responses and feedbacks'.

Fire regimes are changing across the globe, with new wildfire behaviour phenomena and increasing impacts felt, especially in ecosystems without clear adaptations to wildfire. These trends pose significant challenges to the scientific community in understanding and communicating these changes and their implications, particularly where we lack underlying scientific evidence to inform decision-making. Here, we present a perspective on priority directions for wildfire science research-through the lens of academic and government wildfire scientists from a historically wildfire-prone (USA) and emerging wildfire-prone (UK) country. Key topic areas outlined during a series of workshops in 2023 were as follows: (A) understanding and predicting fire occurrence, fire behaviour and fire impacts; (B) increasing human and ecosystem resilience to fire; and (C) understanding the atmospheric and climate impacts of fire. Participants agreed on focused research questions that were seen as priority scientific research gaps. Fire behaviour was identified as a central connecting theme that would allow critical advances to be made across all topic areas. These findings provide one group of perspectives to feed into a more transdisciplinary outline of wildfire research priorities across the diversity of knowledge bases and perspectives that are critical in addressing wildfire research challenges under changing fire regimes.This article is part of the theme issue 'Novel fire regimes under climate changes and human influences: impacts, ecosystem responses and feedbacks'.

The evolutionary topic we examine here is whether species determine the environment (bottom-up) or if environments shape plant traits (top-down). For the environment, we focus on the fire regime. Many forests are subject to either frequent low-intensity surface fires or less frequent but high-intensity crown fires. What are the ultimate factors controlling these fire regimes? The top-down model proposes that environmental factors controlling productivity and ignitions shape fire regimes; the bottom-up model attributes them to different plant assemblies. In boreal forests, it is assumed that, because of the similar climate, forests of North America and Eurasia undergo distinct fire regimes (crown-fire and surface-fire regimes, respectively) due to bottom-up forces. We tested the hypothesis that fire regimes are primarily controlled by top-down factors by selecting congeneric species of Pinus and Picea from both continents. Plots dominated by each species were studied using remote sensing data. We then compared environmental conditions where the species occur and found that Eurasian tree species occur in warmer and more productive environments than North American tree species. Our results support the top-down model, which suggests that environmental factors control the surface- versus crown-fire regime in boreal forests.This article is part of the theme issue 'Novel fire regimes under climate changes and human influences: impacts, ecosystem responses and feedbacks'.