Natural disturbances influence wetland carbon cycling, and fire is a key driver of terrestrial carbon stocks. However, the influence of fire on wetland carbon cycling remains poorly understood. Here, we investigated how prescribed fire and wildfire impact soil carbon storage in a forested floodplain of south-eastern Australia. We sampled four areas within Murray Valley National Park, the world’s largest river red gum (Eucalyptus camaldulensis) stand, and compared soil carbon (C), nitrogen (N) and C:N ratios between control (unburnt in the 50 years prior to sampling), prescribed burn and wildfire-impacted floodplain areas. Mean soil C and N concentrations were 4.7% ± 0.32% and 0.36% ± 0.02%, respectively, and mean C:N ratios were 14.23 ± 0.33. Carbon concentrations and C:N were highest in control areas of the floodplain, while N concentrations were highest at wildfire-impacted areas. However, flood frequency was a stronger driver of soil C than fire disturbance. Soils at more frequently flooded areas had higher C concentrations compared to less frequently flooded areas, suggesting that resilience to C loss through fire could be enhanced through hydrological restoration. We believe this warrants further research as a potential nature-based climate measure. Mean C density data indicate soil C stocks of 9.4 Tg across Barmah-Millewa Forest, highlighting the significant carbon storage value of this ecosystem.

Nothofagus alessandrii, categorized as Endangered on the IUCN Red List, is an endemic, deciduous tree species of the coastal range of central Chile. We assessed the effects of fire severity, invasion by the exotic fire-prone Pinus radiata, and land-cover composition and configuration of the landscape on the resilience of fragments of N. alessandrii after a mega-fire in 2017. We used remote sensing data to estimate land-use classes and cover, fire severity and invasion cover of P. radiata. We monitored forest composition and structure and post-fire responses of N. alessandrii forests in situ for 2 years after the mega-fire. In the coastal Maule region wildfires have been favoured by intense drought and widespread exotic pine plantations, increasing the ability of fire-adapted invasive species to colonize native forest remnants. Over 85% of N. alessandrii forests were moderately or severely burnt. The propagation and severity of fire was probably amplified by the exotic pines located along the edges of, or inside, the N. alessandrii fragments and the highly flammable pine plantations surrounding these fragments (> 60% of land use is pine plantations). Pinus radiata, a fire-adapted pioneer species, showed strong post-fire recruitment within the N. alessandrii fragments, especially those severely burnt. Positive feedback between climate change (i.e. droughts and heat waves), wildfires and pine invasions is driving N. alessandrii forests into an undesirable and probably irreversible state (i.e. a landscape trap). A large-scale restoration programme to design a diverse and less flammable landscape is needed to avoid the loss of these highly threatened forest ecosystems.

Wildfires have become a regular seasonal disaster across the Western region of the United States. Wildfires require a multifaceted disaster response. In addition to fire suppression, there are public health and medical needs for responders and the general population in the path of the fire, as well as a much larger population impacted by smoke. This paper describes key aspects of the health and medical response to wildfires in California, including facility evacuation and shelter medical support, with emphasis on the organization, coordination, and management of medical teams deployed to fire incident base camps. This provides 1 model of medical support and references resources to help other jurisdictions that must respond to the rising incidence of large wildland fires.

Analyses of macroscopic charcoal, sediment geochemistry (%C, %N, C/N, δ13C, δ15N), and fossil pollen were conducted on a sediment core recovered from Stella Lake, Nevada, establishing a 2000 year record of fire history and vegetation change for the Great Basin. Charcoal accumulation rates (CHAR) indicate that fire activity, which was minimal from the beginning of the first millennium to AD 750, increased slightly at the onset of the Medieval Climate Anomaly (MCA). Observed changes in catchment vegetation were driven by hydroclimate variability during the early MCA. Two notable increases in CHAR, which occurred during the Little Ice Age (LIA), were identified as major fire events within the catchment. Increased C/N, enriched δ15N, and depleted δ13C values correspond with these events, providing additional evidence for the occurrence of catchment-scale fire events during the late fifteenth and late sixteenth centuries. Shifts in the vegetation community composition and structure accompanied these fires, with Pinus and Picea decreasing in relative abundance and Poaceae increasing in relative abundance following the fire events. During the LIA, the vegetation change and lacustrine geochemical response was most directly influenced by the occurrence of catchment-scale fires, not regional hydroclimate.

Estimates of plant biomass are helpful for many applications in invasive plant science and management, but measuring biomass can be time-consuming, costly, or impractical if destructive sampling is inappropriate. The objective of this study was to assess feasibility of developing regression equations using a fast, nondestructive measure (cover) to estimate aboveground biomass for red brome (Bromus rubens L.), a widespread nonnative annual grass in the Mojave Desert, USA. At three study sites, including one measured for three consecutive years, B. rubens cover spanned 0.1% to 85% and aboveground biomass 1 to 321 g m−2. In log10-transformed linear regressions, B. rubens cover accounted for 68% to 96% of the variance in B. rubens biomass among sites, with all coefficients of determination significant at P < 0.05. For every doubling of percent cover, biomass was predicted to increase by 78%, 83%, and 144% among the three sites. At the site measured for three consecutive years, which ranged in rainfall from 65% to 159% of the long-term average, regression slopes each year differed from other years. Regression results among sites were insensitive to using cover classes (10 classes encompassing 0% to 100% cover) compared with simulated random distribution of integer cover within classes. Biomass of B. rubens was amenable to estimation in the field using cover, and such estimates may have applications for modeling invasive annual plant fuel loads and ecosystem carbon storage.

Wildfires are an integral part of most terrestrial ecosystems. Paleofire records composed of charcoal, soot, and other combustion products deposited in lake and marine sediments, soils, and ice provide a record of the varying importance of fire over time on every continent. This study reviews paleofire research to identify lessons about the nature of fire on Earth and how its past variability is relevant to modern environmental challenges. Four lessons are identified. First, fire is highly sensitive to climate change, and specifically to temperature changes. As long as there is abundant, dry fuel, we can expect that in a warming climate, fires will continue to grow unusually large, severe, and uncontrollable in fire-prone environments. Second, a better understanding of “slow” (interannual to multidecadal) socioecological processes is essential for predicting future wildfire and carbon emissions. Third, current patterns of burning, which are very low in some areas and very high in others—are often unprecedented in the context of the Holocene. Taken together, these insights point to a fourth lesson—that current changes in wildfire dynamics provide an opportunity for paleoecologists to engage the public and help them understand the potential consequences of anthropogenic climate change.

Vegetation assemblages and associated disturbance regimes are spatially heterogeneous in mountain ecosystems throughout the world due to the complex terrain and strong environmental gradients. Given this complexity, numerous sites describing postglacial vegetation and fire histories are needed to adequately understand forest development and ecosystem responses to varying climate and disturbance regimes. To gain insight into long-term historical climate–fire–vegetation interactions in southeastern British Columbia, Canada, sedimentological and paleoecological analyses were performed on a sediment core recovered from a small subalpine lake. The pollen assemblages, stomata, and macroremains indicate that from 9500 to 7500 cal yr BP, Pinus-dominated forests occurred within the catchment and Alnus was also present. Climate was an important control of fire and fire frequency was highest at this time, peaking at 8 fires 1000 yr− 1, yet charcoal accumulation rates were low, indicative of low terrestrial biomass abundance. From 7500 to 4600 cal yr BP, Pinus decreased as Picea, Abies and Larix increased and fire frequencies decreased to 3–6 fires 1000 yr− 1. Since 7500 cal yr BP the fire regime varied at a millennial scale, driven by forest biomass abundance and fuel accumulation changes. Local scale (bottom-up) controls of fire increased in relative importance since at least 6000 cal yr BP.

Paleoenvironmental reconstructions are important for understanding the influence of long-term climate variability on ecosystems and landscape disturbance dynamics. In this paper we explore the linkages among past climate, vegetation, and fire regimes using a high-resolution pollen and charcoal reconstruction from Morris Pond located on the Markagunt Plateau in southwestern Utah, USA. A regime shift detection algorithm was applied to background charcoal accumulation to define where statistically significant shifts in fire regimes occurred. The early Holocene was characterized by greater amounts of summer precipitation and less winter precipitation than modern. Ample forest fuel and warm summer temperatures allowed for large fires to occur. The middle Holocene was a transitional period between vegetation conditions and fire disturbance. The late Holocene climate is characterized as cool and wet reflecting an increase in snow cover, which reduced opportunities for fire despite increased availability of fuels. Similarities between modern forest fuel availability and those of the early Holocene suggest that warmer summers projected for the 21st century may yield substantial increases in the recurrence and ecological impacts of fire when compared to the fire regime of the last millennium.

Forest fires convert a proportion of the burning vegetation into charcoal that is stored in forest soils and lake sediments. In this paper we use a geostatistical approach to present a detailed analysis of the size of the charcoal pool and its spatial variation in a boreal forest watershed including its lake sediment. The amount of soil charcoal averaged 179 g/m2 and ranged from 0 to 3600 g/m2 in the watershed. There was an extreme variation in the size of the charcoal pool over fine (cm) spatial scales. For example, the amount of charcoal in the soil could range from 34 to 1646 g/m2 within a distance of 10 cm. Individually dated soil charcoal particles had radiocarbon ages that varied from 630 to 2930 cal yr BP. The lake sediment began accumulating at 10,600 cal yr BP and charcoal accumulation has been practically continuous ever since then, with the largest peak occurring at 6900 cal yr BP. The lake sediment contained more charcoal, 360 g/m2, than the average for forest soil. We interpret this as an indication of a relatively rapid degradation of charcoal in boreal forest soils.

Fire is unlikely to be a simple, deterministic process that will result in increased rates of invasion by nonnative plants. Relative dominance of nonnative plants at any postfire site likely results from a combination of factors, including propagule pressure (aboveground and belowground), time since invasion, interspecific competition, disturbance history, rainfall patterns, soil nutrients, environmental heterogeneity, land use, plus the actual fire dynamics. Consequently, the role different factors play in nonnative plant invasion is still relatively unexplained, and the possibility that wildfire may promote nonnative plant species remains a concern. Our aim was to evaluate the state of knowledge concerning how nonnative plant species establish, survive, and spread following wildfire in wildland areas for the main vegetation types of the Intermountain West. Although the particular invading species varied with vegetation type, the most frequently reported species were annual grasses (e.g., downy brome [Bromus tectorum], Japanese brome [Bromus japonicus]) and long-distance, dispersing forbs (e.g., Canada thistle [Cirsium arvense], common dandelion [Taraxacum officinale], and prickly lettuce [Lactuca serriola]). Overall, many of the reviewed studies found an increase, followed by a long-term decline, in nonnative species after wildfire, particularly when other disturbances were minimal. Regardless of this finding, many people consider rapid detection and control of new, nonnative plant populations after wildfire one of the most effective management activities. That axiom may be correct, if the nonnative propagule pressure is high and the anthropogenic disturbances are frequent, but if this is not the case the question to answer is whether immediate management, including reseeding, will benefit the system or whether off-target effects could make that approach undesirable. Continued investigation and increased quantitative analysis of the complex factors that likely contribute to changes in nonnative plants dynamics following wildfire should improve our understanding of the issue and assist managers in allocating limited resources.