Post-fire Recovery Research Articles

Designing a Multitemporal Analysis of Land Use Changes and Vegetation Indices to Assess the Impacts of Severe Forest Fires Before Applying Control Measures

Forest fires represent a significant intersection between nature and society, often leading to the loss of natural resources, soil nutrients, and economic opportunities, as well as causing desertification and the displacement of communities. Therefore, the objective of this work is to analyze the multitemporal conditions of a sixth-generation forest fire through the use and implementation of tools such as remote sensing, photointerpretation with geographic information systems (GISs), thematic information on land use, and the use of spatial indices such as the Normalized Difference Vegetation Index (NDVI), the Normalized Burned Ratio (NBR), and its difference (dNBR) with satellite images from Sentinel-2. To improve our understanding of the dynamics and changes that occurred due to the devastating forest fire in Los Guájares, Granada, Spain, in September 2022, which affected 5194 hectares and had a perimeter of 150 km, we found that the main land use in the study area was forest, followed by agricultural areas which decreased from 1956 to 2003. We also observed the severity of burning, shown with the dNBR, reflecting moderate–low and moderate–high levels of severity. Health and part of the post-fire recovery process, as indicated by the NDVI, were also observed. This study provides valuable information on the spatial and temporal dimensions of forest fires, which will favor informed decision making and the development of effective prevention strategies.

Study on the Evolutionary Characteristics of Post-Fire Forest Recovery Using Unmanned Aerial Vehicle Imagery and Deep Learning: A Case Study of Jinyun Mountain in Chongqing, China

Forest fires pose a significant threat to forest ecosystems, with severe impacts on both the environment and human society. Understanding the post-fire recovery processes of forests is crucial for developing strategies for species diversity conservation and ecological restoration and preventing further damage. The present study proposes applying the EAswin-Mask2former model based on semantic segmentation in deep learning using visible light band data to better monitor the evolution of burn areas in forests after fires. This model is an improvement of the classical semantic segmentation model Mask2former and can better adapt to the complex environment of burned forest areas. This model employs Swin-Transformer as the backbone for feature extraction, which is particularly advantageous for processing high-resolution images. It also includes the Contextual Transformer (CoT) Block to better capture contextual information capture and incorporates the Efficient Multi-Scale Attention (EMA) Block into the Efficiently Adaptive (EA) Block to enhance the model’s ability to learn key features and long-range dependencies. The experimental results demonstrate that the EAswin-Mask2former model can achieve a mean Intersection-over-Union (mIoU) of 76.35% in segmenting complex forest burn areas across different seasons, representing improvements of 3.26 and 0.58 percentage points, respectively, over the Mask2former models using ResNet and Swin-Transformer backbones, respectively. Moreover, this method surpasses the performance of the DeepLabV3+ and Segformer models by 4.04 and 1.75 percentage points, respectively. Ultimately, the proposed model offers excellent segmentation performance for both forest and burn areas and can effectively track the evolution of burned forests when combined with unmanned aerial vehicle (UAV) remote sensing images.

Measuring the ecological outcomes of fire: metrics to guide fire management

BackgroundChanges to fire regimes threaten biodiversity worldwide and emphasize the need to understand the ecological consequences of fire management. For fire management to effectively protect biodiversity, it is essential to have ecologicallyrelevant metrics to plan and evaluate management interventions. Here, we describe a suite of metrics to guide fire management for enhanced biodiversity outcomes.ResultsWe define five metrics that collectively provide comprehensive and complementary insights into the effect of fire regimes on ecosystem resilience and components of biodiversity. These include (1) Species Habitat Availability, a measure of the amount of suitable habitat for individual species; (2) Fire Indicator Species Index, population trends for species with clear fire responses; (3) Vegetation Resilience, a measure of plant maturity and the capability of vegetation communities to regenerate after fire; (4) Desirable Mix of Growth Stages, an indicator of the composition of post-fire age-classes across the landscape; and (5) Extent of High Severity Fire, a measure of the effect of severe fire on post-fire recovery of treed vegetation communities. Each metric can be quantified at multiple spatial and temporal scales relevant to evaluating fire management outcomes. We present a case study from Victoria, Australia, in which two metrics are applied across spatially-nested management areas. Results highlight four characteristics of metrics that enhance their value for management: (1) they quantify both status and trends through time; (2) they are scalable and can be applied consistently across management levels (from individual reserves to the whole state); (3) most can be mapped, essential for identifying where and when to implement fire management; and (4) their complementarity provides unique insights to guide fire management for ecological outcomes.ConclusionsThese metrics reflect common relationships between fire and biodiversity and are relevant to management in fire-prone ecosystems worldwide. They facilitate consistent translation of management responsibilities (planning, evaluation, reporting) across administrative levels and enable managers to strategically plan on-ground actions and transparently evaluate outcomes against strategic goals. A key next step for fire managers globally is to define “desirable” states for ecological metrics, to enable target-setting and the evaluation of management outcomes.

Mapping and assessment of ecological vulnerability to wildfires in Europe

BackgroundWildfires play a significant and complex role in ecosystems, influencing various aspects of their functioning and structure. These natural disturbances can positively and negatively impact ecosystems, shaping landscapes, nutrient cycles, biodiversity, and ecological processes. This study focuses on assessing and integrating the different factors that affect the ecological vulnerability to wildfires at the European scale. Our methodology follows three steps. Firstly, ecological values based on biological distinctiveness and conservation status were estimated to understand pre-fire conditions better. Secondly, we obtain vegetation’s coping capacity (or resistance) to the impacts of fire, considering the functional traits of plants and fire characteristics through a fire extreme scenario. Finally, post-fire recovery time was calculated by considering the species-specific recovery time, recovery starting time, growth recovery rate, and the environmental constraints affecting the optimal vegetation response. These three variables were combined using a dynamic model that assumed the change of value due to wildfires integrated throughout the recovery time.ResultsOur results indicate that the tundra biome emerges as the most ecologically vulnerable to fire, primarily due to its high ecological values and long recovery time, which outweigh its moderate coping capacity. Following closely, the temperate conifer forests also exhibit high vulnerability driven by their high recovery time, despite moderate ecological and coping capacity values. The boreal forests rank next, with moderate vulnerability due to their long recovery time and moderate coping capacity. The Mediterranean region, although having moderate ecological values and recovery time, shows a notable vulnerability influenced by lower coping capacity. The temperate broadleaf and mixed forests demonstrate relatively lower vulnerability owing to their balanced ecological values, moderate recovery time, and substantial coping capacity. Lastly, the temperate grasslands, savannas, and shrublands are the least vulnerable, benefiting from lower ecological values and the fastest recovery time, alongside moderate coping capacity, which collectively reduce their overall fire vulnerability.Furthermore, we found that coping capacity is the factor that most influenced ecological vulnerability to wildfires.ConclusionsThe study identifies key zones for European or national policies on fire prevention and post-wildfire regeneration. It offers insights into effective forest management and conservation policies, applicable to current conditions. Additionally, the methods can predict future ecological vulnerability to wildfires based on climatic and socio-economic trends.

Post-fire vegetation dynamic patterns and drivers in Greater Hinggan Mountains: Insights from long-term remote sensing data analysis

Fire has become a major disturbing factor in boreal forests, and giant forest disturbances play a vital role in regulating the climate under global warming. Therefore, it is essential to investigate the spatiotemporal patterns and main drivers of post-fire vegetation recovery for forest ecological research and post-fire recovery management. However, previous studies have focused on the post-fire forest change within the entire fire perimeter, lacking separate analysis and comparison of the burned zone (BZ) and unburned zone (UNBZ). Here, we propose the utilization of Moderate Resolution Imaging Spectroradiometer land cover type and vegetation index data to monitor vegetation dynamics and explore its drivers after the most serious forest fire in the history of P.R. China in the Greater Hinggan Mountains (GHM). The temporal and spatial patterns of vegetation recovery in the BZ/UNBZ in the GHM were analyzed using the Sen & Mann-Kendall method, Hurst index and coefficient of variation, and their driving mechanisms were explored using GeoDetector and geographically weighted regression. The results showed that there were significant differences in the spatial distribution and fluctuation of vegetation between the BZ and UNBZ, and that the BZ exhibited higher productivity and vigor. Vegetation recovery was influenced by different dominant factors and changed over time, in which land surface temperature and precipitation dominated all the time, whereas topographic relief and elevation had a more significant contribution to vegetation recovery in the BZ and UNBZ, respectively. This study provides a scientific basis for the protection and management of vegetation in disturbed forested areas, particularly after fires.

Droughts Amplify Soil Moisture Losses in Burned Forests of Southeastern Amazonia

AbstractSoil moisture is a crucial variable mediating soil‐vegetation‐atmosphere water exchange. As climate and land use change, the increased frequency and intensity of extreme weather events and disturbances will likely alter feedbacks between ecosystem functions and soil moisture. In this study, we evaluated how extreme drought (2015/2016) and postfire vegetation regrowth affected the seasonality of soil water content (0–8 m depth) in a transitional forest in southeastern Amazonia. The experiment included three treatment plots: an unburned Control, an area burned every three years (B3yr), and an area burned annually (B1yr) between 2004 and 2010. We hypothesized that (a) soil moisture at B1yr and B3yr would be higher than the Control in the first years postfire due to lower transpiration rates, but differences between burned plots would decrease as postfire vegetation regrew; (b) during drought years, the soil water deficit in the dry season would be significantly greater in all plots as plants responded to greater evaporative demand; and (c) postfire recovery in the burned plots would cause an increase in evapotranspiration over time, especially in the topsoil. Contrary to the first expectation, the burned plots had lower volumetric water content than the Control plot. However, we found that droughts significantly reduced soil moisture in all plots compared to non‐drought years (15.6%), and this effect was amplified in the burned plots (19%). Our results indicate that, while compounding disturbances such as wildfires and extreme droughts alter forest dynamics, deep soil moisture is an essential water source for vegetation recovery.

Fire Impacts on Soil Properties and Implications for Sustainability in Rotational Shifting Cultivation: A Review

Fire, a prevalent land management tool in rotational shifting cultivation (RSC), has long been debated for its immediate disruption of surface soil, vegetation, and microbial communities. While low-intensity and short-duration slash-and-burn techniques are considered beneficial for overall soil function, the dual nature of fire’s impact warrants a comprehensive exploration. This review examines both the beneficial and detrimental effects of fire on soil properties within the context of RSC. We highlight that research on soil microbial composition, carbon, and nitrogen dynamics following fire events in RSC is gaining momentum. After fires, soil typically shows decreases in porosity, clay content, aggregation, and cation exchange capacity, while sand content, pH, available phosphorus, and organic nitrogen tend to increase. There remains ongoing debate regarding the effects on bulk density, silt content, electrical conductivity, organic carbon, total nitrogen, and exchangeable ions (K+, Ca2+, Mg2+). Certain bacterial diversity often increases, while fungal communities tend to decline during post-fire recovery, influenced by the soil chemical properties. Soil erosion is a major concern because fire-altered soil structures heighten erosion risks, underscoring the need for sustainable post-fire soil management strategies. Future research directions are proposed, including the use of advanced technologies like remote sensing, UAVs, and soil sensors to monitor fire impacts, as well as socio-economic studies to balance traditional practices with modern sustainability goals. This review aims to inform sustainable land management practices that balance agricultural productivity with ecological health in RSC systems.

Post-fire Recovery Dynamics and Resilience of Ecosystem Services Capacity in Mediterranean-Type Ecosystems

Post-fire Recovery Dynamics and Resilience of Ecosystem Services Capacity in Mediterranean-Type Ecosystems

Post-fire recovery of nematode communities along a slope gradient in a pine forest.

We investigated the enduring consequences of a wildfire on nematode diversity and abundance in a pine forest, employing a slope gradient approach. Our primary objective was to determine the extent of post-fire alterations in the nematode community 3years after the incident, to understand if the ecosystem has returned to its pre-fire state or has transitioned to a distinctive ecological environment. Three distinct burned pine forest sites at varying elevations were sampled to capture short-scale soil property variations due to slope gradients, while unburned forest sites served as controls. A consistent pattern emerged where the lowest altitude sites exhibited the highest nematode abundances, although still lower than unburned sites. Fire-induced changes were profound, shifting from fungivore dominance in unburned sites to bacterivore and herbivore dominance in burned sites. Alterations in soil properties post-fire, particularly reduced organic matter and nitrogen content, were closely associated with nematode community shifts. Water availability played a crucial role with lower moisture levels at higher elevations impacting nematode populations. Structural differences in the nematode community primarily resulted from fire disturbance rather than altitude. This study emphasizes the persistent and transformative impact of wildfire on nematode communities, highlighting the intricate interplay between ecological disturbances, soil properties, and nematode trophic dynamics.

Long-term post-fire recovery of an oribatid mite assemblage: A case study from a temperate coniferous forest

Wildfire represents a significant natural disturbance factor in forest ecosystems expected to further increase in importance due to global climate change. It has a detrimental short-term impact on soil biota, but much less is known about its long-term effects, especially on soil mesofauna. Our study compared oribatid assemblages of the forest floor in moderately-burned forest sites along a post-fire chronosequence (8 fire history classes covering 0–110 years since fire) with near-by reference sites without fire history. All sites were situated on acidic soils in the Central European Elbe Sandstone Mountains (Bohemian Switzerland National Park, NW Czechia), mostly covered by pine and spruce forests. Data were analysed using linear mixed-effect models. We found a substantial impact of fire on oribatid assemblages. Whereas lower densities were observed for the first few years after a fire only, changes in assemblage feeding guilds persisted over at least four decades. Shifts towards smaller body size, parthenogenesis and fungivory at burned sites compared to larger body size, sexual reproduction and detritivory in unburned controls implied changes in assemblage functioning. The changes in functional traits, which correspond to previous research findings on the recovery of oribatid mites after clear-cutting, underscore a more universal pattern of post-disturbance development.

Variable persistence of an iconic arboreal mammal through the Black Summer wildfires

Wildfires are predicted to increase in frequency and severity with climate change but detailed understanding of their influence on forest wildlife is lacking for many species. Wildfires vary in their extent and severity among landscapes, limiting generalisations about impacts from a single wildfire. We investigated post-wildfire persistence in the threatened exudivorous yellow-bellied glider (Petaurus australis) in south-eastern Australia. The widespread occurrence of wildfires in the ‘Black Summer’ of 2019–20 enabled populations in three landscapes (90–160 km apart) to be studied. This species has a slow life history (one young per year and >1 year to mature) so post-fire recovery is predicted to be slow. We conducted repeat surveys over 3 years post-fire in each landscape at 25–29 sites that were occupied pre-wildfire. All survey sites were burnt in two landscapes but only 40 % were burnt in the third. We estimated declines in occupancy of 13 %, 40 % and 66 % in burnt forest. The factors driving the variation in decline appear to be a combination of fire severity and the abundance of very large (≥80 cm) hollow (i.e. cavity) -bearing trees that serve as den sites. The implications of this study are that the impacts of wildfires on populations of tree-hollow dependent species can be expected to vary in different landscapes as a consequence of fire severity, rainfall deficit and logging history. Our study suggests the importance of ensuring populations are conserved across a wide geographic gradient, and the value of very large hollow-bearing trees rather than simply the number of any hollow-bearing trees.

Anatomy of a post-wildfire recovery: Responses of mammals to a Black Summer wildfire in a fox-free landscape

Wildfires are predicted to increase in frequency and severity with climate change. Devising effective strategies to ensure wildfires do not hasten a decline in wildlife populations hinges on developing a deeper understanding of how species are affected by recent wildfires. I investigated the response of eight species of medium-sized mammals over a 4-year period (2020–2023) following a wildfire in the Australian Black Summer fire season. Pre-wildfire population levels were not known. These species differed in their ability to survive the passage of fire; from being able to flee the fire front, to remaining in protective shelters, to favouring unburnt forest types, to none of these strategies. Camera trapping was conducted from 5 months to 4 years after the fire across 62 sites in wet and dry sclerophyll forest (burnt and unburnt) and rainforest (unburnt) to characterise both initial survival and subsequent reproduction-led post-fire occupancy. There was consistency in the response of species in year 1. Those assumed to be able to flee the fires showed medium-high post-fire occupancy regardless of whether a site was burnt. Those that use protective shelters and unburnt forest also showed high occupancy. One species without these options showed greatly reduced occupancy in year 1 relative to years 3 and 4. Most species showed evidence of increased detection across years, which is inferred to reflect increased abundance, and was expected given substantially above average rainfall for three years following the fire. The feral cat was the only predator sufficiently widespread to be of concern in species’ recovery but was rarely detected in years 1 and 2, relative to years 3 and 4. This study provides evidence that many species, including three threatened species, have the ability to survive the passage of fire, and show high post-fire occupancy. The study landscape contained abundant habitat elements (unburnt rainforest, boulder fields) that promote survival through a wildfire and post-fire recovery, providing insights to guide future conservation actions.

Fire refugia patch dynamics differ between prescribed fires and wildfires in longleaf pine savanna

Increasing wildfire activity has spurred an increasing push for the application of prescribed fire to reduce wildfire risk while simultaneously acting as a surrogate for fire’s historical role as a fundamental ecosystem process. However, prescribed fires are often ignited using uniform ignitions to maintain operational control and there are concerns that they may not be able to replicate the landscape heterogeneity, particularly patterns in unburned patches, generated by historical fires. Fire refugia, unburned areas within fire perimeters, play an integral role in determining post-fire recovery and community structure. We assess patterns in fire refugia across 443 large (>200 ha) wildfire and prescribed fire perimeters using remotely sensed fire severity data in longleaf pine (Pinus palustris) savannas of the Florida Panhandle. Contrary to concerns, large prescribed fires had a significantly greater proportion of unburned area than wildfires, driven by larger refugia patch sizes. Drier conditions promoted smaller and more numerous fire refugia patches. Our study demonstrates differences in wildfires versus prescribed fire outcomes on landscape structure, with implications for future longleaf pine savanna management.

Microenvironment heterogeneity affected by anthropogenic wildfire-perturbed soil mediates bacterial community in Pinus tabulaeformis forests.

In recent years, the frequency and intensity of anthropogenic wildfires have drastically increased, significantly altering terrestrial ecosystems worldwide. These fires not only devastate vegetative cover but also impact soil environments and microbial communities, affecting ecosystem structure and function. The extent to which fire severity, soil depth, and their interaction influence these effects remains unclear, particularly in Pinus tabulaeformis forests. This study investigated the impact of wildfire intensity and soil stratification on soil physicochemical properties and microbial diversity within P. tabulaeformis forests in North China. Soil samples were collected from different fire severity zones (Control, Light, Moderate, High) and depths (topsoil: 0-10 cm; subsoil: 10-20 cm). Analyses included measurements of soil pH, organic carbon (SOC), total nitrogen (TN), and other nutrients. Microbial diversity was assessed using 16S rRNA gene sequencing. Our findings revealed significant variations in soil pH, SOC, TN, and other nutrients with fire severity and soil depth, profoundly affecting microbial community composition and diversity. Soil pH emerged as a critical determinant, closely linked to microbial α-diversity and community structure. We found that fire severity significantly altered soil pH (p = 0.001), pointing to noteworthy changes in acidity linked to varying severity levels. Topsoil microbial communities primarily differentiated between burned and unburned conditions, whereas subsoil layers showed more pronounced effects of fire severity on microbial structures. Analysis of bacterial phyla across different fire severity levels and soil depths revealed significant shifts in microbial communities. Proteobacteria consistently dominated across all conditions, indicating strong resilience, while Acidobacteriota and Actinobacteriota showed increased abundances in high-severity and light/moderate-severity areas, respectively. Verrucomicrobiota were more prevalent in control samples and decreased significantly in fire-impacted soils. Chloroflexi and Bacteroidota displayed increased abundance in moderate and high-severity areas, respectively. Correlation analyses illustrated significant relationships between soil environmental factors and dominant bacterial phyla. Soil organic carbon (SOC) showed positive correlations with total nitrogen (TN) and alkaline hydrolysable nitrogen (AN). Soil pH exhibited a negative correlation with multiple soil environmental factors. Soil pH and available phosphorus (AP) significantly influenced the abundance of the phylum Myxococcota. Soil water content (WC) significantly affected the abundances of Acidobacteriota and Actinobacteriota. Additionally, ammonium nitrogen (NH4 +-N) and nitrate nitrogen (NO3 --N) jointly and significantly impacted the abundance of the phylum Chloroflexi. This study highlights the significant long-term effects of anthropogenic wildfires on soil microenvironment heterogeneity and bacterial community structure in P. tabulaeformis forests in North China, 6 years post-fire. Our findings demonstrate that fire severity significantly influences soil pH, which in turn affects soil nutrient dynamics and enhances microbial diversity. We observed notable shifts in the abundance of dominant bacterial phyla, emphasizing the critical role of soil pH and nutrient availability in shaping microbial communities. The results underscore the importance of soil stratification, as different soil layers showed varying responses to fire severity, highlighting the need for tailored management strategies. Future research should focus on long-term monitoring to further elucidate the temporal dynamics of soil microbial recovery and nutrient cycling following wildfires. Studies investigating the roles of specific microbial taxa in ecosystem resilience and their functional contributions under varying fire regimes will provide deeper insights. Additionally, exploring soil amendments and management practices aimed at optimizing pH and nutrient availability could enhance post-fire recovery processes, supporting sustainable ecosystem recovery and resilience.

Stimulated photosynthesis of regrowth after fire in coastal scrub vegetation: increased water or nutrient availability?

Fire-prone landscapes experience frequent fires, disrupting above-ground biomass and altering below-ground soil nutrient availability. Augmentation of leaf nutrients or leaf water balance can both reduce limitations to photosynthesis and facilitate post-fire recovery in plants. These modes of fire responses are often studied separately and hence are rarely compared. We hypothesized that under severe burning, woody plants of a coastal scrub ecosystem would have higher rates of photosynthesis (Anet) than in unburned areas due to a transient release from leaf nutrient and water limitations, facilitating biomass recovery post-burn. To compare these fire recovery mechanisms in regrowing plants, we measured leaf gas exchange, leaf and soil N and P concentrations, and plant stomatal limitations in Australian native coastal scrub species across a burn sequence of sites at 1 year after severe fire, 7 years following a light controlled fire, and decades after any fire at North Head, Sydney, Australia. Recent burning stimulated increases in Anet by 20% over unburned trees and across three tree species. These species showed increases in total leaf N and P as a result of burning of 28% and 50% for these macronutrients, respectively, across the three species. The boost in leaf nutrients and stimulated leaf biochemical capacity for photosynthesis, alongside species-specific stomatal conductance (gs) increases, together contributed to increased photosynthetic rates after burning compared with the long-unburned area. Photosynthetic stimulation after burning occurred due to increases in nutrient concentrations in leaves, particularly N, as well as stomatal opening for some species. The findings suggest that changes in species photosynthesis and growth with increased future fire intensity or frequency may be facilitated by changes in leaf physiology after burning. On this basis, species dominance during regrowth depends on nutrient and water availability during post-fire recovery.

Modelling postfire recovery of snow albedo and forest structure to understand drivers of decades of reduced snow water storage and advanced snowmelt timing

AbstractForest fires darken snow albedo and degrade forest structure, ultimately reducing peak snow–water storage, and advancing snowmelt timing for up to 15 years following fire. To date, no volumetric estimates of watershed‐scale postfire effects on snow–water storage and snowmelt timing have been quantified over decades of postfire recovery. Using postfire parameterizations in a spatially‐distributed snow mass and energy balance model, SnowModel, we estimated postfire recovery of forest fire effects on snow–water equivalent (SWE) and snowmelt timing over decades following fire. Using this model, we quantified volumetric recovery of forest fire effects on snow hydrology across a chronosequence of eight sub‐alpine forests burned between 2000 and 2019 in the Triple Divide of western Wyoming. We found that immediately following fire, forest fire effects reduced snow–water storage by 6.8% (SD = 11.2%) and advanced the snow disappearance date by 31 days (SD = 9 days). Across the 15‐year recovery following fire, forest fire effects reduced snow–water storage by 4.5% (SD = 11.4%). Postfire effects on snow hydrology generally recovered over time, but still persisted beyond 15‐years following fire due to the observed postfire shift from forest to open meadow. Estimates of postfire reductions on peak SWE summed over the entire 15‐year postfire recovery period were 18 times greater than the immediate losses in the first winter following fire alone. These lasting effects of forest fires on snow hydrology decades following fire highlight the importance of postfire parameterizations for more accurate watershed‐scale volumetric estimates of forest fire effects on snow–water resources.

Assessment of Pinus halepensis Forests’ Vulnerability Using the Temporal Dynamics of Carbon Stocks and Fire Traits in Tunisia

Carbon stocks provide information that is essential for analyzing the role of forests in global climate mitigation, yet they are highly vulnerable to wildfires in Mediterranean ecosystems. These carbon stocks’ exposure to fire is usually estimated from specific allometric equations relating tree height and diameter to the overall amount of aboveground carbon storage. Assessments of vulnerability to fire additionally allow for specific fire resistance (bark thickness, crown basal height) and post-fire recovery traits (cone mass for regeneration, and fine branches or leaves mass for flammability) to be accounted for. These traits are usually considered as static, and their temporal dynamic is rarely assessed, thus preventing a full assessment of carbon stocks’ vulnerability and subsequent cascading effects. This study aimed to measure the pools of carbon stocks of individual trees varying between 30 and 96 years old in the Djbel Mansour Aleppo pine (Pinus halepensis) forest in semi-arid central Tunisia in the southern range of its distribution to fit a sigmoid equation of the carbon pools and traits recovery according to age as a vulnerability framework. Allometric equations were then developed to establish the relationships between fire vulnerability traits and dendrometric independent variables (diameter at breast height, height, and live crown length) for further use in regional vulnerability assessments. The total carbon stocks in trees varied from 29.05 Mg C ha−1 to 92.47 Mg C ha−1. The soil organic carbon stock (SOC) at a maximum soil depth of 0–40 cm varied from 31.67 Mg C ha−1 to 115.67 Mg C ha−1 at a soil depth of 0–70 cm. We could identify an increasing resistance related to increasing bark thickness and basal crown height with age, and enhanced regeneration capacity after 25 years of age with increasing cone biomass, converging toward increasing vulnerability and potential cascading effects under shorter interval fires. These results should be considered for rigorous forest carbon sequestration assessment under increasing fire hazards due to climate and social changes in the region.

A fast spectral recovery does not necessarily indicate post-fire forest recovery

BackgroundClimate change has increased wildfire activity in the western USA and limited the capacity for forests to recover post-fire, especially in areas burned at high severity. Land managers urgently need a better understanding of the spatiotemporal variability in natural post-fire forest recovery to plan and implement active recovery projects. In burned areas, post-fire “spectral recovery”, determined by examining the trajectory of multispectral indices (e.g., normalized burn ratio) over time, generally corresponds with recovery of multiple post-fire vegetation types, including trees and shrubs. Field data are essential for deciphering the vegetation types reflected by spectral recovery, yet few studies validate spectral recovery metrics with field data or incorporate spectral recovery into spatial models of post-fire vegetation recovery. We investigated relationships between spectral recovery and field measurements of post-fire recovery (16 to 27 years post-fire) from 99 plots in mixed conifer forests of the Blue Mountains, USA. Additionally, using generalized linear mixed effects models, we assessed the relative capacities of multispectral, climatic, and topographic data to predict field measurements of post-fire recovery.ResultsWe found that a fast spectral recovery did not necessarily coincide with field measurements of forest recovery (e.g., density of regenerating seedlings, saplings, and young trees and % juvenile conifer cover). Instead, fast spectral recovery often coincided with increases in % shrub cover. We primarily attributed this relationship to the response of snowbrush ceanothus, an evergreen shrub that vigorously resprouts post-fire. However, in non-trailing edge forests—where it was cooler and wetter and fast-growing conifers were more common—rapid spectral recovery coincided with both increases in % shrub cover and forest recovery. Otherwise, spectral recovery showed potential to identify transitions to grasslands, as grass-dominated sites showcased distinctly slow spectral trajectories. Lastly, field measurements of post-fire forest recovery were best predicted when including post-fire climate and multispectral data in predictive models.ConclusionsDespite a disconnect between a fast spectral recovery and forest recovery, our results suggest that including multispectral data improved models predicting the likelihood of post-fire forest recovery. Improving predictive models would aid land managers in identifying sites to implement active reforestation projects.Graphical Photo credit: J. Celebrezze

Identification of main variables in forest management for recovery of endemic species habitat in burned areas of southern Chile

Wildfires are among the most serious disturbances that affect forest biodiversity, damaging both flora and fauna. In some burned areas, vegetation recovery is a long and complex process that requires the support of restorative actions. This study evaluated changes in forest structural features after a fire that affect habitat suitability for Rhinocryptids, an endemic group of bird species that are indicators of biodiversity in the temperate forests of South America. The study area was the Malleco National Reserve, Chile, where the main ecosystems are temperate forests. Four species from the Rhinocryptidae family of birds were used as bioindicator species. This group of species is endemic to temperate forests in South America. After fires occurred in 2002 and 2015, affecting temperate forests dominated by several Nothofagus species, two field inventories were carried out in 2016 and 2018. These inventories recorded the presence of Rhinocryptids and some forests structural features. Differences between the two stages of forest regeneration were assessed using statistical tests (T-test and Wilcoxon–Mann–Whitney test) and a classification model was proposed to determine the presence of Rhinocryptidae species. The statistical analysis of forest structural features showed that the variables more relevant in the habitat recuperation are vertical stratification (p-value < 0.001) and understory cover (p-value = 0.053). The trained decision tree to predict the presence of Rhinocryptidae species had an accuracy of 65.22%. This model showed that the coexistence of more than one Rhinocryptidae species occurs when vertical stratification is not mono-stratified and the density is lower than 335 trees ha−1. Our results can help forest managers to consider forest structure as a suitable habitat for certain major wildlife species when implementing post-fire recovery plans.

Fractionation of Inorganic Phosphorus in Cold Temperate Forest Soils: Associating Mechanisms of Soil Aggregate Protection and Recovery Periods after Forest Fire Disturbance

The soil aggregate is the fundamental unit of soil structure. The fractionation characteristics and influencing factors of phosphorus (P) in soil aggregates inherently link its geochemical characteristics and recycling mechanism. This work investigated the fractionation characteristics of inorganic P in cold temperate forest soils and studied the impacts of recovery periods after forest fires and soil aggregate protection mechanisms on P fractionation. Our results showed that the TP, active P, stable P, and total organic carbon (TOC) contents varied with increasing recovery years after forest fire disturbance. The TP content in the coarse particulate organic matter fraction (cPOM) exhibited an increasing trend with the number of recovery years. Redundancy analysis (RDA) and correlation analysis indicated that TOC played a crucial role in influencing the dynamics of P fractionation during the recovery process. The order of TP levels in different soil aggregate fractions was as follows: μClay &gt; dClay &gt; LF &gt; cPOM &gt; dSilt &gt; μSilt &gt; iPOM, with significant contributions from the cPOM and dSilt fractions. The ranking of P fractions in bulk soils was as follows: ACa-P &gt; Fe-P &gt; Oc-P &gt; Or-P &gt; De-P &gt; Al-P &gt; Ex-P. The protective mechanism of soil aggregates had a more significant effect on TOC than TP, with the order of protective abilities being: Phy×biochem-protected &gt; Biochem-protected &gt; Phy-protected &gt; Non-protected mechanism. TOC and recovery years emerged as critical factors influencing the dynamics of different P fractions during post-fire recovery. Soil aggregate protection mechanisms demonstrated significantly higher effects on TOC than on TP. This study provides insights into the fractionation mechanisms of P in the soil–forest ecosystem of the Greater Khingan Mountains, contributing to the sustainable development and utilization of cold temperate forest ecosystems.