The underlying datasets have provided a foundation for numerous wildfire studies in the continental United States over the past two decades, but discrepancies among their records can complicate efforts to determine how many individual fires occurred and how large they were. Kasischke and French began by mining information from the three national sources, then combined it with regional reports, regional datasets and information found through searches of the world wide web. Fires not represented in the original national datasets were added when the broader search identified them as distinct events. The resulting inventory is intended to improve the information available for quantifying annual area burned and changes in extreme wildfire activity at different spatial scales.

Much of the work focused on records whose descriptions or measurements did not align. The researchers developed specific approaches for cases in which the same fire appeared with substantially different reported sizes, fires were labeled as complexes, several fires were contained within a larger event, smaller events merged into a larger one, events later joined, sizes were reported incorrectly or records were duplicated. These are consequential distinctions for event-based inventories because the treatment of a complex incident affects both the number assigned to a fire and the area attributed to it. The database seeks to reconcile these cases before researchers aggregate individual records into annual, regional or national totals.

Calculations using the integrated database increase total burned area for all United States regions. They also yield more extreme wildfires—defined in the study’s short summary as events larger than 5,000 hectares—and a larger area burned by events above that threshold. The authors present these results as differences between measurements generated from the new event database and those obtained from the records currently used by the fire-science community, rather than as projections of future wildfire activity. The comparison illustrates how the number, size and classification of recorded events can shape estimates of burned area and the prevalence of extreme fires across the full 1992–2021 inventory.

The work is a preprint and has not yet completed the journal’s review process. The supplied record states that the manuscript was received on 23 August 2026 and entered discussion on 21 October 2026, with a supplement also available from the preprint record. Its geographic scope is the continental United States, and its temporal scope is the three decades from 1992 to 2021. The database also depends on the quality and consistency of the national, regional and web-based information used to construct and reconcile it. Within those limits, the study’s central contribution is methodological: it provides a harmonized inventory of individual wildfire events designed to reduce uncertainties in the counts, areas and extreme-event measurements used in fire-science research.

Subject of Research: An integrated event database for measuring wildfires across the continental United States from 1992 to 2021

Article Title: An integrated wildfire event database for improved fire science research for the continental United States, 1992–2021

Article References: Kasischke, E. S., & French, N. H. (2026). An integrated wildfire event database for improved fire science research for the continental United States, 1992–2021. https://doi.org/10.5194/essd-2026-660

Image Credits: AI Generated

DOI: 10.5194/essd-2026-660

Keywords: wildfire database, burned area, extreme wildfires, United States, fire records, data reconciliation, event classification, 1992–2021, wildfire science, preprint, integrated, wildfire

The reconstruction is based on fluxes of three combustion-derived anhydrosugars. Levoglucosan, produced mainly during the pyrolysis of plant cellulose, served as the principal tracer of biomass burning, while its isomers mannosan and galactosan, formed principally during hemicellulose pyrolysis, helped characterize the relative composition of combusted material. The researchers standardized the three flux records and averaged them to construct a composite fire activity index, or FAI. They compared this index with elemental ratios, total organic carbon, grain-size measurements and climate-model output to examine whether wildfire changes coincided with local hydrological conditions or broader circulation variability.

The chronology came from a Bayesian age-depth model previously established for the Wodi Co core using accelerator mass spectrometry radiocarbon dating, the IntCal20 calibration curve and the rbacon modelling package. The full 880-centimeter core extends from approximately 5,120 years before present to 69 years after present, while the analyzed upper 810 centimeters cover roughly the past 4,550 years and end at about 62 years after present. The model showed no age reversals, although sediment accumulation rates changed substantially, including relatively rapid deposition around 2,300 to 1,600 years before present. Calculating fluxes rather than relying on concentrations alone was therefore important for separating changes in the amount of burned material from changes in the rate at which sediment accumulated.

Stratigraphically constrained clustering divided the molecular fire record into three principal phases. From about 4,550 to 2,885 years before present, the proxies showed generally low to moderate biomass burning. Mean levoglucosan flux was 1.55 ± 1.06 micrograms per square centimeter per year, mean mannosan flux was 0.92 ± 0.33 micrograms per square centimeter per year and mean galactosan flux was 1.90 ± 1.58 micrograms per square centimeter per year. The FAI averaged −0.63 ± 0.64 during this first phase, indicating activity below the full-record average. The most active and variable period followed, extending from roughly 2,885 to 1,946 years before present. Mean levoglucosan flux rose to 3.66 ± 3.27 micrograms per square centimeter per year, while mannosan and galactosan fluxes and the FAI also reached their highest phase averages.

Large standard deviations in the high-fire phase show that the increase was episodic rather than uniform. Several short fire episodes, including a multi-decadal peak near 2,000 years before present, were embedded within the broader interval. The authors note that the peaks may reflect short-lived enhancements in fire intensity or biomass combustion, although variations in fuel availability, atmospheric transport and sedimentary preservation may also have contributed. Since about 1,946 years before present, mean levoglucosan, mannosan and galactosan fluxes declined to 1.25 ± 1.21, 0.98 ± 0.62 and 1.74 ± 1.35 micrograms per square centimeter per year, respectively. The FAI averaged −0.76 ± 0.82 in this final phase, returning activity to levels broadly comparable with those of the earliest phase.

Several lines of evidence pointed toward drier conditions during the high-fire interval. In the Wodi Co catchment, calcium-to-silicon ratios rose as a whole, a pattern interpreted as greater concentration of lake water and reduced effective moisture, although detrital inputs and carbonate sources may also affect the ratio. Conversely, iron-to-manganese ratios declined, consistent with lower lake levels and more oxic sedimentary conditions. Simulated precipitation for the wettest quarter also remained comparatively low, averaging 321.44 ± 4.95 millimeters during the main fire phase. The FAI was significantly correlated with calcium-to-silicon at Spearman’s rho of 0.24 and inversely correlated with iron-to-manganese at rho of −0.34, with both relationships significant at p less than 0.05. By contrast, total organic carbon, the greater-than-64-micrometer fraction and zircon-to-rubidium ratio were not significantly correlated with the principal fire proxies.

Independent statistical tests identified changes at roughly the same broad times. A multiple structural-break analysis selected two FAI transitions, at approximately 2,910 and 1,950 years before present, closely matching the clustering boundaries. The result remained similar when first-order autoregressive errors were included, indicating that moderate temporal autocorrelation did not erase the principal transitions. The iron-to-manganese record also retained two breakpoints, at approximately 1,740 and 2,910 years before present, whereas the calcium-to-silicon breakpoint at about 2,250 years before present was sensitive to the statistical treatment of temporal dependence. The timing of the main fire-state transitions was therefore more robust than the exact timing of every hydrological change.

The broad climate context points to a weakened Indian summer monsoon and enhanced El Niño-like conditions during the principal fire interval. An Oman Cave speleothem oxygen-isotope record indicated relatively weak monsoonal moisture transport, while a sediment record from El Junco Lake in the tropical Pacific indicated pronounced El Niño-like conditions, including the strongest anomaly in the approximately 4,500-year comparison period. These large-scale indicators broadly coincided with the Wodi Co fire episode, although their principal extremes lagged local changes by about 500 years. The ENSO index was significantly associated with lower simulated dry-season relative humidity at the lake, with rho of −0.47 and p less than 0.05, whereas the Indian summer monsoon showed only a weak relationship with that measure, with rho of −0.26 and p below 0.10. The winter westerly jet was positioned slightly farther north during the high-fire phase, at a mean December-to-February latitude of 30.02 ± 1.05 degrees north, but its position was not significantly related to either the moisture indicators or the fire proxies.

After about 2,000 years before present, the transition was marked by reduced and less variable burning, lower calcium-to-silicon, higher iron-to-manganese and a general increase in simulated wet-season precipitation. Mean precipitation for the wettest quarter was 325.15 ± 5.50 millimeters during the final phase, with an overall increase after about 2,100 years before present. The change was also visible in the mean calcium-to-silicon ratio of 0.76 ± 0.21 and iron-to-manganese ratio of 131.92 ± 53.95. This local shift broadly agrees with hydroclimatic reorganizations described across parts of the Asian monsoon domain, although the response was spatially uneven and the exact breakpoints did not match perfectly among records. The authors interpret the Wodi Co change as a local reorganization of the relationship between moisture and wildfire within the broader “2-kyr shift,” rather than as proof that a single event occurred simultaneously everywhere. After the transition, wildfire activity remained generally low and stable.

The reconstruction offers a long-term example of drought-related drying coinciding with greater biomass burning in a high-elevation environment, but it does not establish that moisture alone caused every fire peak. The levoglucosan-to-mannosan ratio ranged from 0.15 to 6.96 and may indicate changes in the relative contribution of woody or herbaceous fuels, yet overlapping fuel signatures, combustion conditions, atmospheric transport and differential preservation prevent it from identifying fuel types conclusively. Organic-carbon accumulation likewise cannot serve as a direct measure of vegetation productivity because it is affected by aquatic production, catchment delivery, degradation and preservation. The Wodi Co catchment also lacks independent archaeological, pollen-based disturbance or anthropogenic-biomarker records, so the magnitude of past human influence cannot be separated confidently from climatic effects, especially during the late Holocene. The study instead supports a moisture-linked regional explanation for the long-term pattern, while treating the Indian summer monsoon, ENSO and westerly circulation as the larger climatic backdrop rather than independent, immediate causes of individual fire episodes.

Subject of Research: Holocene wildfire variability and regional moisture conditions in alpine northwestern Yunnan

Article Title: Regional moisture conditions and mid- to late-Holocene wildfire variability along the southeastern margin of the Tibetan Plateau

Article References: Yang, P., Gao, Y., Hu, C., Kong, L., Chen, G., Chen, J., Li, R., Ma, J., Fu, Z., & Xie, Z. (2026). Regional moisture conditions and mid- to late-Holocene wildfire variability along the southeastern margin of the Tibetan Plateau. Frontiers in Earth Science, 14, Article 1963785. https://doi.org/10.3389/feart.2026.1963785

Image Credits: AI Generated

DOI: 10.3389/feart.2026.1963785

Keywords: paleofire, lake sediments, Wodi Co, Tibetan Plateau, Holocene, wildfire, moisture variability, Indian summer monsoon, ENSO, levoglucosan, Yunnan, Regional

The study focused on direct mortality rather than inferred changes in population size. Researchers walked across burned areas in a zigzag pattern, generally within the first two weeks after a fire and in some cases as late as three weeks, recording every live or dead reptile they encountered. The 2021 survey covered 120.60 hectares during 18 field days and about 300 person-hours, while the 2022 effort surveyed 28.95 hectares over four days and 66 person-hours. Satellite imagery helped identify additional burned areas that could not be visited. Investigators used global positioning system measurements and a geographic information system to calculate areas and densities, while photographs documented animals and their locations. Carcasses were left in place because they can serve as food for predators and scavengers.

Fire affected 196.91 hectares of Sierra Morelos in 2021 and 63.33 hectares in 2022. Authorities reported 35.9 hectares of prescribed burning in 2021, compared with an annual average of 2.65 hectares between 2013 and 2020. The researchers surveyed 23.72 hectares of prescribed burns and 96.88 hectares of unplanned burns in 2021; in 2022, all 28.95 hectares surveyed were prescribed burns. The managed fires were intended to protect plantations of non-native trees, particularly Mexican pine and eucalyptus, which are highly flammable. Unplanned fires included illegal or accidental ignitions associated with agricultural and grazing activities, trash burning near informal settlements, abandoned campfires and discarded cigarettes.

Among the reptiles recorded in the 2021 burned areas, 58 were dead and 111 alive, meaning that 34% of the observed population had been killed. In 2022, 11 were dead and 22 alive, a mortality fraction of 33%. Overall carcass density across all sampled areas was 0.48 individuals per hectare in 2021 and 0.38 per hectare in 2022. The mean among individual sampling sites was considerably more variable, reaching 1.60 ± 2.99 individuals per hectare in 2021 and 0.31 ± 0.27 in 2022. One small prescribed firebreak produced the highest site-level density in 2021, with 12.26 carcasses per hectare, including three garter snakes. By contrast, a large 73.73-hectare site affected by an out-of-control stubble fire contained 20 carcasses, illustrating how total deaths and density can tell different stories.

Prescribed and unplanned burns produced no statistically detectable difference in carcass density in 2021, with a Mann–Whitney U result of W = 37.5 and p = 0.4383. In that year, 53% of reptiles found in prescribed-burn sites were dead, compared with 30% in unplanned-burn sites, but the number of sites and the high variation among them prevented the difference from reaching statistical significance. The researchers also found no relationship between carcass density and a simple measure of fire shape based on area divided by perimeter, which yielded R² = 0.0528 and p = 0.168. That measure did not account for rocks, agave plants, logs, burrows, wind, speed or severity, all of which could influence where animals survived.

The Mexican plateau horned lizard, Phrynosoma orbiculare, was the most frequently killed species and a particularly troubling casualty because it is threatened in Mexico. Twenty horned lizards were found dead in 2021 and four in 2022. The species shelters beneath bunchgrass or leaf litter when inactive and moves slowly, leaving it exposed when flames pass through its cover. Its carcass densities were 0.17 per hectare across the sampled area in 2021 and 0.14 per hectare in 2022. The torquate lizard, Sceloporus torquatus, was far more abundant but had a much lower death rate: nine of 70 observed individuals died in 2021 and three of eight in 2022. Its ability to climb rocks, shrubs, agave plants and fallen logs likely gave it access to more effective refuges. Researchers also noted that three horned lizards were intercepted and moved away from an active fire.

Ground-dwelling snakes were another major casualty. Nineteen garter snakes of the genus Thamnophis were found dead in 2021 and two in 2022. Three of the carcasses showed no visible thermal damage despite lying on completely burned ground. Garter snakes can retreat into burrows and underground cavities, including hollows more than a meter deep, but such protection may not prevent death from smoke inhalation, toxic gases or oxygen depletion. Their presence as intact, apparently unburned bodies on burned surfaces suggests that some may have sheltered below ground during the flames and emerged only after the surrounding vegetation had been consumed. The transvolcanic alligator lizard, Barisia imbricata, was relatively uncommon but yielded 10 carcasses, reinforcing concern that other ground-dwelling species may also have been disproportionately affected.

The observed totals are likely conservative. Carcasses can be hidden beneath ash, fragmented beyond recognition or entirely calcined; one horned lizard was so completely burned that it fell apart when photographed. Predators and scavengers may remove bodies before surveys begin, and the investigators noted that one previous study documented a 20% decline in carcass counts during the second week after fire. Some injured survivors may also have died after the survey through burns, dehydration or indirect effects. Reptiles that survived may have moved away before investigators arrived, and animals dying underground may never have been detectable. Conversely, the researchers excluded likely roadkill or other non-fire deaths from the analysis, and live animals found during surveys were released near burned-area edges to help them escape short-term threats.

Most carcasses in 2021 lay on burned grass, which accounted for 84% of the total, followed by leaf litter, rocky surfaces and bare soil. All carcasses found in 2022 were on burned grass. Even burns conducted in January and February, when reptiles may be less active, occurred during the cold and dry season, but inactivity did not necessarily mean deep shelter. Sierra Morelos has pronounced daily temperature swings, with winter nights sometimes below freezing and daytime temperatures above 20°C. Horned lizards may remain beneath bunchgrass or leaf litter even during cooler periods, placing them directly in the path of burning vegetation. The findings therefore do not support the assumption that winter scheduling alone is sufficient protection in this high-elevation grassland environment.

For conservation, the authors call for changes to fire management in Sierra Morelos and similar regional grasslands. They recommend ending prescribed burns as part of the reserve’s management program while also reducing the larger annual area affected by unplanned fires, which collectively pose a cumulative threat. Suggested measures include maintaining a distributed network of bike paths as firebreaks, rotating small-scale livestock use to limit fuel accumulation without intensifying grazing, replacing flammable pine and eucalyptus plantations with native vegetation, and coordinating dry-season vigilance among nearby communities. Restoring landscape features such as agave plants could provide refuges, while rapid post-fire searches could identify survivors for cooling, relocation or other assistance. More systematic monitoring of live and dead reptiles before and after fire would permit more precise estimates of mortality and help determine which management practices protect vulnerable populations without reducing the frequency of unplanned ignition.

Subject of Research: Direct fire-induced mortality among reptiles in a Mexican natural protected area

Article Title: Direct fire-induced reptile mortality in the Sierra Morelos natural protected area (Mexico)

Article References: González-Fernández, A., Couturier, S., Dotor-Diego, R., Martínez-Díaz-González, R., & Sunny, A. (2024). Direct fire-induced reptile mortality in the Sierra Morelos natural protected area (Mexico). Herpetozoa, 37, 213-226. https://doi.org/10.3897/herpetozoa.37.e116376

Image Credits: AI Generated

DOI: 10.3897/herpetozoa.37.e116376

Keywords: reptile mortality, wildfire, prescribed burning, Sierra Morelos, Mexico, hornied lizards, garter snakes, fire ecology, protected areas, anthropogenic fire, Direct, fire-induced

The study, led by Azad Rasul of Soran University and Salahaddin University in Erbil together with Ismahil Shkur Zahir, relied on the MODIS MCD64A1 Version 6.1 burned-area product, a widely used satellite dataset that maps the monthly location and extent of vegetation fires worldwide. To isolate forest fires from fires in grasslands, croplands, and shrublands, the team masked the burned-area data to a forest mask derived from 2024 vegetation greenness measurements, yielding a forested area of approximately 10,660 square kilometers. All processing was carried out on the Google Earth Engine platform, which allows planetary-scale geospatial analysis without the need to download and process terabytes of raw satellite imagery locally. Over the full 24-year record, cumulative burned area across the entire region reached 16,486 square kilometers, while forest-specific burned area totaled 8,541 square kilometers.

Detecting a genuine trend in noisy fire data requires more than eyeballing a time series, and the researchers applied two complementary statistical tests. The Theil–Sen slope estimator, a robust non-parametric method that resists distortion by extreme fire years, quantified the magnitude of change, while the Mann–Kendall test assessed whether the trend was statistically significant rather than a product of random interannual variability. For total burned area across the region, the Mann–Kendall test returned a p-value of 0.026, and for forest burned area it returned 0.021, both below the conventional 0.05 threshold for significance. The high year-to-year variability, reflected in a standard deviation of 640 square kilometers around the 687 square kilometer mean for total burned area, underscores why robust trend methods are essential in fire science: a single catastrophic season can otherwise dominate the apparent trajectory.

Geography mattered as much as time. The governorates of Duhok and Sulaymaniyah together accounted for 77 percent of the cumulative forest burned area over the study period, and both displayed the strongest upward trends in the region. This spatial concentration is consistent with the distribution of the Zagros oak forests, which form the ecological backbone of Kurdistan’s mountainous terrain. These forests, dominated by oak species such as Quercus aegilops, are not only biodiversity reservoirs but also support grazing, fuelwood collection, and a suite of characteristic wildlife, including the endangered Persian leopard. Repeated burning at the observed rate of over 3 percent of forest cover per year raises serious questions about whether these ecosystems can regenerate between fires, particularly as climate change pushes growing conditions toward the physiological limits of the oaks themselves.

To identify the climatic drivers behind the trends, the researchers modeled burned area as a function of monthly maximum temperature and drought severity, the latter expressed as the negated Palmer Drought Severity Index, so that positive values indicate drier conditions. Because burned-area data are counts of burned pixels with many zero values in wet or cool months, the team employed a zero-inflated count model, a statistical framework that simultaneously estimates the probability that a fire occurs at all and the expected size of the fire when one does occur. The results were unambiguous on the temperature side: each 1 degree Celsius rise in monthly maximum temperature increased expected burned area by 14.3 percent, an incidence-rate ratio of 1.143 with a p-value below 0.001. This temperature sensitivity aligns with a large body of global research showing that warmer conditions dry out fuels, extend fire seasons, and increase the probability of ignition and spread.

The drought result was more surprising and scientifically intriguing. In the count model predicting fire magnitude, drought severity was significantly and negatively associated with burned area, with an incidence-rate ratio of 0.787, meaning each unit increase in drought severity reduced expected fire size by 21.3 percent, and the zero-inflation component showed a similar but non-significant pattern with a p-value of 0.417. At first glance, a negative drought-fire relationship seems counterintuitive, since drought is conventionally associated with heightened fire risk. Yet similar non-linear relationships have been documented in Mediterranean-type climates, where moderate drought stimulates the growth of grasses and shrubs that later cure into abundant fine fuel, whereas extreme, prolonged drought suppresses vegetation productivity so severely that there is simply less biomass available to burn. In Kurdistan’s semi-arid mountains, this fuel-limitation dynamic appears to shape the fire regime as strongly as atmospheric dryness does.

The model outputs also revealed pronounced non-linear escalation of predicted fire activity above approximately 32 degrees Celsius in monthly maximum temperature and above a negated PDSI value of 2, corresponding to severe drought conditions. Below these thresholds, predicted fire activity remained comparatively modest; above them, expected burned area climbed steeply. This threshold behavior has practical implications for fire management, because it suggests that relatively small additional increments of warming in already-hot months could push the region across a fire-activity tipping point. The Eastern Mediterranean and Middle East are among the fastest-warming regions on Earth, and climate projections for northern Iraq indicate continued increases in temperature and greater frequency of extreme heat events, making the observed 14.3 percent per degree sensitivity a sobering baseline for future risk.

The Kurdistan Region’s fire regime cannot be understood through climate alone, and the study’s findings sit within a broader context of conflict, land use, and environmental change. Previous research has documented how decades of armed conflict in the Zagros forests, including the Iran–Iraq war era, reshaped land use and forest management, and how fire has been used both as collateral damage and as a deliberate instrument of war in the region. Geopolitical analyses of fire in Kurdistan have highlighted the challenges of environmental peacebuilding when burning is entangled with territorial disputes and agricultural practices. While the new study focuses on climatic predictors rather than attributing specific fires to human causes, the strong upward trends in Duhok and Sulaymaniyah likely reflect an interaction between a warming, drying climate and socio-economic pressures on forest landscapes, from expansion of agriculture to changes in traditional grazing and land stewardship.

Methodologically, the study demonstrates the power of combining freely available satellite products with cloud-based computation and rigorous trend statistics to build a fire-climate baseline in data-sparse regions. The MODIS burned-area algorithm detects changes in surface spectral properties following fire, and its Collection 6 version incorporates improvements in burn date assignment and small-fire detection. Pairing this with TerraClimate and ERA5-Land reanalysis data for temperature and drought indices allowed the researchers to link fire outcomes to monthly climatic conditions at fine spatial resolution. The zero-inflated modeling approach, though less common in fire-climate studies than simple regression, is well suited to the skewed, zero-heavy distribution of burned-area data and helps separate the question of whether fires occur from the question of how large they become.

For the oak forests of Kurdistan, the message of the analysis is that fire is no longer an occasional disturbance but a growing, climate-linked pressure that demands proactive management. The identification of temperature and drought thresholds offers concrete early-warning markers: months exceeding 32 degrees Celsius in maximum temperature, especially when combined with severe drought conditions, are the periods when fire activity escalates most dramatically. As regional temperatures continue to rise under climate change, the frequency with which those thresholds are crossed will only increase, and the 15 square kilometer annual growth in forest burned area may prove to be a conservative indicator of what lies ahead. Protecting these forests will require not only firefighting capacity but also land-use policies that reduce fuel accumulation and human ignition sources, informed by the kind of quantitative, long-term evidence this study now provides for one of the Middle East’s most ecologically and culturally significant mountain forest systems.

Subject of Research: Long-term trends and climatic drivers of forest burned area in the Kurdistan Region of Iraq from 2001 to 2024

Article Title: Assessing trends and drivers of burned areas in forest areas in the Kurdistan Region

Article References: Rasul, A., & Zahir, I. S. (2026). Assessing trends and drivers of burned areas in forest areas in the Kurdistan Region. Environmental Monitoring and Assessment, 198(9), Article 1016. https://doi.org/10.1007/s10661-026-15838-5

Image Credits: AI Generated

DOI: 10.1007/s10661-026-15838-5

Keywords: wildfire, Kurdistan Region, MODIS burned area, oak forests, climate change, drought, Palmer Drought Severity Index, remote sensing, Mann-Kendall trend, Zagros forests, fire ecology, Iraq

The study, led by Davood Mafi-Gholami of the Standard Research Institute in Karaj, with Abolfazl Jaafari of Iran’s Research Institute of Forests and Rangelands and Binh Thai Pham of the University of Transport Technology in Hanoi, addresses a persistent blind spot in forest vulnerability science. Most vulnerability assessments, the authors note, still rest on single-hazard frameworks, even though the Intergovernmental Panel on Climate Change has repeatedly emphasized that real-world risk emerges from the interaction of climatic, environmental and human stressors. In a region where climate change and intensifying land use are accelerating ecological degradation, a single-lens approach risks underestimating the pressure on ecosystems that are already operating close to their physiological limits.

To build a more faithful picture, the team constructed a geographic information system-based multicriteria framework that integrates nine factors contributing to exposure: drought, actual evapotranspiration, wildfire, high-speed winds, maximum temperature, floods, landslides, dust storms and social vulnerability. Each hazard layer was standardized and then harmonized to a common 30-meter resolution, allowing the signals of very different phenomena, from atmospheric moisture demand to slope instability, to be combined cell by cell into a single continuous exposure index across the forest landscape. The choice of a fine spatial grain matters, because hazard intensity in mountain terrain can change dramatically over distances of a few hundred meters as elevation, aspect and land cover shift.

Weighting the relative importance of nine heterogeneous stressors is one of the most contested steps in composite risk mapping, and the researchers approached it through a structured expert elicitation process using Delphi-derived weights within a multicriteria decision analysis. This technique, long established in GIS-based decision support, iteratively refines expert judgments until they converge, producing a transparent set of relative weights that can be applied consistently across the entire study area. It also makes the model auditable: because the weights and the standardization procedures are explicit, other research teams can reproduce the index or adapt it to other mountain forest systems facing similar combinations of pressures.

Perhaps the most important technical feature of the study is that its outputs were tested against the real world rather than accepted on faith. The authors compiled 448 independent disturbance records, drawing on documented locations of oak decline, field-observed forest degradation sites and wildfire hotspots distributed across the Zagros. When these records were overlaid on the exposure index, 75 percent of them fell within the high and very high exposure classes. For a purely synthetic composite index, that level of agreement with independently mapped disturbance is a meaningful validation result, and it suggests the framework is capturing genuine spatial structure in where the forests are actually breaking down rather than merely producing a smooth statistical artifact.

Among the nine hazards, drought emerged as the dominant contributor to exposure, followed by wildfire and social vulnerability. That ordering tells a coherent ecological story. The Zagros woodlands, dominated by drought-sensitive oak species such as Quercus brantii, have experienced repeated severe droughts in recent decades, and satellite-based monitoring has documented substantial canopy losses associated with them. Prolonged water stress weakens trees, and weakened trees are in turn more flammable and more susceptible to pests and pathogens, which is one mechanism by which the region’s well-documented oak decline phenomenon is thought to propagate. Meanwhile, social vulnerability, reflecting the capacity of forest-dependent communities to absorb and recover from shocks, ranked third, underscoring that in this landscape ecological risk and human risk are inseparable.

The second major finding concerns canopy structure, which forms the conceptual core of the paper’s title. The researchers found that exposure increased consistently as canopy cover declined, with sparsely forested stands showing both the greatest concentration and the greatest spatial continuity of high-risk zones. This is more than a correlation of degraded land with degraded conditions. Canopy cover functions as a physical regulator of the microclimate beneath it: closed canopies moderate surface temperatures, reduce evaporative demand, protect soils from erosion, and slow the spread of fire by interrupting continuous fuel beds. As canopies thin, these buffering functions erode, and the underlying land becomes simultaneously hotter, drier, more erosion-prone and more fire-prone, feeding a feedback loop that pushes stands further from recovery.

The spatial pattern of this feedback is what makes the new index operationally valuable. Because exposure was computed at 30-meter resolution, the map distinguishes between isolated high-risk pixels and large contiguous zones where high exposure dominates the landscape. Continuity matters for managers: a fragmented high-risk patch may be stabilized through targeted interventions, whereas an extensive connected zone of sparsely canopied, drought-stricken, fire-prone forest represents a landscape-scale degradation corridor in which restoration efforts must be prioritized and concentrated. The authors position the framework as a practical decision support tool for exactly this purpose, applicable to restoration planning, climate adaptation, risk management and conservation prioritization in climate-sensitive mountain forests far beyond Iran.

The broader scientific significance of the work lies in its treatment of the exposure component of vulnerability. In the widely used vulnerability frameworks of sustainability science, vulnerability is decomposed into exposure, sensitivity and adaptive capacity, and the exposure term has often been the least spatially refined. By building a high-resolution, multi-stressor, validated exposure surface and then explicitly relating it to canopy structure, the study demonstrates that forest architecture is not merely a passive attribute of the ecosystem but an active regulator of how much environmental hazard the system actually experiences. That reframing has direct implications for how vulnerability models are parameterized, since stand structure data from remote sensing can now inform not only sensitivity estimates but exposure estimates as well.

For the Zagros forests themselves, the message is urgent. The region sits at a climatic crossroads where projections indicate continued warming and shifting precipitation regimes, and prior studies have shown that anthropogenic activities amplify wildfire occurrence across the eco-region. The new exposure map does not predict the future, but it identifies where the accumulated weight of drought, fire, dust, floods, landslides, heat, wind and social fragility is already greatest, and where the loss of canopy cover is converting scattered stress into concentrated, self-reinforcing risk. In a warming century, the authors suggest, protecting and restoring canopy structure in the most exposed zones may be among the most cost-effective levers available for keeping these irreplaceable mountain forests, and the communities that depend on them, from crossing thresholds from which recovery is no longer possible.

Subject of Research: Multihazard exposure assessment and the role of canopy structure in forest vulnerability in the Zagros forests of Iran

Article Title: Spatially explicit assessment of multihazard exposure in the Zagros forests of Iran: the role of canopy structure in the exposure component of forest vulnerability

Article References: Mafi-Gholami, D., Jaafari, A., & Pham, B. T. (2026). Spatially explicit assessment of multihazard exposure in the Zagros forests of Iran: the role of canopy structure in the exposure component of forest vulnerability. Environmental Monitoring and Assessment, 198(9), Article 1019. https://doi.org/10.1007/s10661-026-15874-1

Image Credits: AI Generated

DOI: 10.1007/s10661-026-15874-1

Keywords: Zagros forests, multihazard exposure, forest vulnerability, drought, wildfire, oak decline, canopy cover, GIS multicriteria analysis, social vulnerability, climate change, Iran, spatial modeling

The findings carry weight far beyond a single warbler species. The Hermit Warbler has previously been identified as a surrogate species for the California Spotted Owl, and among more than 60 Sierra Nevada bird species analyzed in prior work, 13 are co-associated with the Spotted Owl, none more strongly than the Hermit Warbler. Because the warbler’s small body size means a small home range, researchers can monitor it with far greater sample sizes than the owl, giving them the statistical power to detect subtle population responses to environmental change that will likely apply to the larger, more charismatic species sharing the same old-forest habitat. In this sense, the warbler functions as a biological barometer for an entire community of old-forest specialists facing the combined pressures of warming and intensifying fire regimes.

To capture population dynamics at an ecosystem scale, the research team deployed autonomous recording units, known as ARUs, at 876 locations spanning six National Forests across the western slope of the Sierra Nevada. Each summer from 2021 through 2024, pairs of recorders were placed 500 to 900 meters apart, with 1.5 to 3 kilometers between pairs, and left running for approximately five weeks. The devices recorded continuously through a single omni-directional microphone at a sample rate of 32 kilohertz. For analysis, the team focused on audio captured between 5:00 and 9:00 in the morning and 6:00 to 8:00 in the evening, the windows when Hermit Warbler vocalizations are most likely to be heard. The study area ranged from 328 meters above sea level, where black oak mingles with ponderosa pine, up to 2,528 meters, where white fir dominates the canopy.

The acoustic data were processed with BirdNET, a convolutional neural network capable of identifying Hermit Warbler songs and the vocalizations of thousands of other species by sound. To ensure the AI’s predictions were trustworthy, the researchers manually validated 200 randomly selected BirdNET detections of Hermit Warbler vocalizations, half drawn from a broad score range and half from the upper range, then fit a logistic regression relating the prediction score to the probability that a given detection was correct. Only predictions with a probability of being a true positive of at least 0.99 were retained as observations. At this stringent threshold, precision was a perfect 1.0, meaning every retained detection was correct, while recall was 0.78, meaning the detector captured 78 percent of the target sounds actually present. This combination of extremely high precision and strong recall meant false positives and false negatives would have minimal influence on the final results.

Quantifying the environmental conditions at each recording site required equally sophisticated remote sensing. The team characterized fire severity and history using 30-meter resolution rasters of the Composite Burn Index, generated in Google Earth Engine from random forest models parameterized with latitude, climatic water deficit, and spectral indices from Landsat imagery spanning 1985 to 2023. Composite Burn Index values of 2.25 or higher were categorized as high-severity fire, corresponding to at least 75 percent canopy mortality. Fire data were summarized within a 120-meter buffer around each recorder as the proportion of unburned, low-to-moderate, and high-severity fire occurring 1 to 10 and 11 to 35 years before each sampling year. For the thermal environment, the researchers used 30-meter resolution mean relative summer temperature derived from the Landsat 8 Thermal Infrared Sensor, calculated from 2013 to 2018 as a median across a six-year time series. This in situ thermal measurement, rather than coarser gridded weather data interpolated from sparse stations, captured fine-scale conditions such as slope and aspect in the Sierra’s complex terrain.

A critical statistical challenge emerged because relative temperature and mean tree diameter were strongly negatively correlated, with a correlation coefficient of negative 0.77. Sites with larger trees are simply cooler. To disentangle these effects, the team fit a linear model of relative temperature as a function of tree diameter and used the residuals as a forest-structure-corrected measure of the thermal environment. Positive residuals indicated sites warmer than expected given their tree diameter, negative residuals indicated sites cooler than expected, and the resulting corrected measure was uncorrelated with tree diameter. This allowed the researchers to ask whether the warbler responded to temperature itself, independent of the forest structure that both creates cooler microclimates and defines the species’ preferred habitat.

The population dynamics were analyzed with a dynamic occupancy model, a hierarchical statistical framework that estimates site occupancy, colonization, and local extinction while accounting for imperfect detection. Each breeding season was divided into eight six-day secondary sampling periods, and the team applied careful filters to create encounter histories: observations before June 1 or after July 18 were excluded because they could reflect migration or post-breeding movement rather than stable breeding behavior, and any site with only a single vocalization in June was treated as unoccupied to guard against transient individuals or rare high-scoring false positives. Detection probability was modeled as a function of survey effort and ordinal date. Initial occupancy was modeled as a function of elevation, latitude, mean tree diameter, the temperature-corrected residuals, and the amount of high-severity fire in the prior ten years, while colonization and extinction were modeled against the same covariates. All covariates were scaled to allow direct effect size comparisons, and the team considered a covariate influential if the 85 percent confidence interval around its estimate did not overlap zero.

The results painted a coherent picture of a species contracting its range under pressure from both direct and indirect effects of climate change. Site occupancy fell from 0.658 in 2021 to 0.603 in 2024, an 8.3 percent decline. Initial occupancy was most strongly influenced by mean tree diameter, confirming the warbler’s old-forest association, but even after controlling for forest structure, birds were more likely to occupy sites cooler than expected for their tree diameter. Occupancy showed a striking non-linear latitudinal gradient: approximately 0.1 at the southern end of the study area, climbing to 0.78 slightly north of the midpoint near the South Fork of the American River, and reaching 0.84 at the northernmost extent. Colonization rates were higher in the north while extinction rates were higher in the south, producing a clear northward shift in the relative density of occupied sites. Elevation told a more complicated story: colonization increased with elevation, but extinction displayed a positive quadratic relationship, meaning the lower elevational boundary shifted upslope while the upper boundary did not show an unambiguous corresponding expansion.

The fire response was dramatic. At a completely unburned site, the annual probability of local extinction was 0.106 and the probability of colonization was 0.383. At a fully burned site, extinction probability soared to 0.883 while colonization collapsed to 0.0292. The warbler showed a strong extinction response to severe fire over a 1-to-10-year post-fire period and failed to colonize such areas over the same span, effectively treating locally extensive high-severity fire as a decadal loss of habitat. Notably, colonization was unaffected by high-severity fire occurring 11 to 35 years before the study period, suggesting some capacity for resilience if enough unburned habitat remains. The observed population decline could plausibly be attributed to the several large, severe fires that occurred during the study window, including the Dixie Fire, which burned almost 3,900 square kilometers of the northern Sierra Nevada with more than 20 percent at high severity, along with the Caldor and KNP Complex Fires. The apparent northward shift of the warbler population may have partially offset the Dixie Fire’s local effects, underscoring the importance of regional context when interpreting local studies.

The study’s implications for conservation are sobering but actionable. Limiting the occurrence of large, severe fires will be necessary to preserve this old-forest indicator, the authors conclude, but not sufficient: rising temperatures will lead to population declines even in the absence of habitat loss due to fire. Without proactive strategies that move away from strict fire suppression and incorporate principles of pre-colonial fire stewardship, continued intensification of contemporary fire regimes could drive further declines for the Hermit Warbler and the species that share its habitat. Meanwhile, the mixed evidence for upslope shifts suggests that simply moving to higher elevations may not be a viable climate adaptation strategy for the warbler, the Spotted Owl, or their co-associated species, particularly since high-elevation Sierra forests are not expected to provide short- to intermediate-term climate refugia due to complex interactions between canopy cover, microclimate, and prey. As climate change accelerates, understanding how species respond to shifting environmental conditions will be crucial for guiding adaptive management and ensuring the persistence of biodiversity in fire-prone landscapes, and this four-year bioacoustic monitoring framework offers a scalable template for tracking those responses across entire ecosystems.

Subject of Research: Combined effects of warming temperatures and high-severity wildfire on the range dynamics of an old-forest bird species in the Sierra Nevada

Article Title: Warm temperatures and severe fire drive a range contraction of an avian old-forest specialist in the Sierra Nevada, USA

Article References: Bielski, L., Keyser, S. R., Peery, M. Z., & Wood, C. M. (2026). Warm temperatures and severe fire drive a range contraction of an avian old-forest specialist in the Sierra Nevada, USA. Frontiers in Bird Science, 5, Article 1737313. https://doi.org/10.3389/fbirs.2026.1737313

Image Credits: AI Generated

DOI: 10.3389/fbirs.2026.1737313

Keywords: Hermit Warbler, Sierra Nevada, climate change, high-severity fire, passive acoustic monitoring, dynamic occupancy model, old-growth forest, range contraction, BirdNET, wildfire, bird conservation, Spotted Owl

The research team, led by M. M. Rago and M. F. Urretavizcaya of the Andean Patagonian Forest Research and Extension Center (CIEFAP) and Argentina’s National Scientific and Technical Research Council (CONICET), established 45 permanent plots spanning five forest types and three fire severity levels. The forests studied were dominated by Nothofagus pumilio, N. antarctica, N. dombeyi, Austrocedrus chilensis, and a mixed N. dombeyi–A. chilensis type — together accounting for 72 percent of the burned area. Plots were placed in unburned refugia, moderately burned sites, and severely burned ground, with three replicates for every combination of severity and forest type. When the team returned in January through March 2021, they sampled every vascular plant species, measured its aerial cover, and classified the community into three vertical strata below three meters in height.

The technical backbone of the study was a permutational multivariate analysis of variance, or PERMANOVA, built on Bray-Curtis distances calculated from species cover at each site. The analysis controlled for spatial autocorrelation using distance-based Moran’s eigenvector maps, ensuring that the patterns detected were not simply artifacts of plots lying close together in a mountainous valley. The results were unambiguous: both fire severity and forest type significantly shaped understory composition, with no interaction between the two. Fire severity explained 7 percent of the variation in plant assemblages, while forest type explained 14 percent — a larger share that reflects the strong environmental heterogeneity of the region, where precipitation drops from 2,400 millimeters in the west to 800 millimeters in the east across a single valley.

Indicator species analysis sharpened the picture considerably. In unburned sites, only native species served as indicators — among them the herb Osmorhiza berteroi and the fern Rumohra adiantiformis. In moderately burned sites, the native nitrogen-fixing herb Vicia nigricans and the violet Viola magellanica stood out with high fidelity. But in severely burned sites, the indicator list included exotic species: the annual herb Crepis capillaris and Epilobium brachycarpum, the latter a highly specific marker of recently disturbed ground. The team recorded 124 taxa across 48 families in total, the vast majority native and many endemic to South America, with native perennial herbs and shrubs dominating the growth forms throughout.

The trait-level comparisons revealed how fire severity acts as an ecological filter on community assembly. Total species richness peaked in moderate-severity sites at 23.6 species per 0.53 square meters, compared with 17.4 in unburned forests and 19.9 in high-severity sites — a pattern the authors attribute to the coexistence of fire-sensitive survivors and newly establishing colonizers. Native richness followed the same trajectory. Exotic cover, by contrast, was roughly five percentage points higher in both burned categories than in unburned sites, and the highest exotic richness appeared in burned N. dombeyi and mixed N. dombeyi–A. chilensis forests. Annual herbs, a hallmark of early disturbance, showed nearly four times the cover in high-severity sites compared with unburned ground. Nitrogen-fixing species and resprouting species both reached their greatest cover in moderate-severity sites, suggesting that moderately burned ground is actively rebuilding soil nutrient pools depleted by combustion.

Vertical structure told its own story. Overstory cover — the living canopy of foundational trees — was highest in unburned plots, as expected. But the upper understory stratum, between 1.5 and 3 meters, was most developed in high-severity sites, where shrubs such as Fabiana imbricata, Schinus patagonica, Aristotelia chilensis, and Ribes magellanicus had taken advantage of the sudden flood of light. The middle stratum, between 0.5 and 1.5 meters, was instead most developed in moderate-severity sites, dominated by perennial herbs and vines including Vicia nigricans, Mutisia decurrens, and the bamboo Chusquea culeou. The lower stratum, below half a meter, showed no significant differences across severity levels, indicating that ground-level cover had largely recovered within six years regardless of how hot the fire burned.

Regeneration data delivered the study’s most consequential finding. Among plots with pre-fire evidence of Chusquea culeou — the semelparous bamboo that flowers synchronously roughly every 60 years, then dies, producing masses of highly flammable dry biomass — regeneration occurred in 78 percent of moderate-severity plots but in only 20 percent of high-severity plots. In severely burned ground, the few cases of bamboo recovery were restricted to rhizome resprouting and appeared exclusively in N. pumilio forest. Seed regeneration of the foundational tree species, which depend entirely on seed dispersal from nearby unburned individuals because their wind-dispersed seeds travel only a few hundred meters and they lack persistent seed banks, was detected in 53 percent of unburned plots and 47 percent of moderate-severity plots — but in just 7 percent of high-severity plots, corresponding to a single N. dombeyi site.

The timing of the Las Horquetas fire added a rare ecological twist. It coincided with the post-flowering death of Chusquea culeou, which had flowered and seeded the year before — the same coincidence that accompanied historic fires in the region more than a century ago and in the widespread fire year of 1944. The bamboo’s post-flowering die-off created a pulse of flammable fuel that helped drive the blaze, yet its freshly produced seeds also offered a narrow window for post-fire recovery. The study’s results suggest that window closes quickly where severity is high: without surviving rhizomes or nearby seed sources, both the bamboo and the trees it once sheltered face strongly limited short-term re-establishment.

The broader implications reach beyond Patagonia. Fire regimes are intensifying worldwide, with more severe, frequent, and larger fires expanding the extent of early successional landscapes. In forests dominated by fire-sensitive species that cannot resprout and hold only transient seed banks, high-severity fires that burn large areas can push ecosystems past a threshold, shifting them toward flammable shrublands or grasslands — alternative stable states reinforced by positive fire-vegetation feedbacks. The Patagonian findings align with this framework: severely burned sites, with their shrub-dominated upper strata and depressed tree regeneration, are consistent with potentially divergent successional pathways that could lock in non-forest states, while moderately burned sites appear more likely to return to forest structure, particularly where tree seedlings were detected.

Land-use history compounds the challenge. The Cholila basin’s primary pre-fire land use was cattle grazing, and although the study did not quantify it, signs of livestock — dung and browsing — were recorded in several plots. Previous research in Andean-Patagonian forests has shown that introduced herbivores and fire act synergistically, altering plant reproductive phenology and facilitating the spread of exotic species. The elevated exotic cover in burned N. antarctica and N. dombeyi forests may therefore reflect not only fire-driven resource release and reduced competition, but also variation in grazing intensity and human activity across the landscape. For restoration practitioners, the message is clear: severity is the filter, forest type is the template, and grazing is the wildcard. Understanding the structure and dynamics of these early post-fire understory communities, the authors conclude, is essential for guiding burned ecosystems toward desirable states while sustaining the ecological processes — soil protection, nutrient cycling, and wildlife habitat — that early successional communities provide, and for maintaining the resilience of Patagonia’s temperate forests under fire regimes that show every sign of intensifying further.

Subject of Research: Understory vegetation development six years after a wildfire in the temperate forests of Patagonia, Argentina

Article Title: Understory vegetation development six years after a wildfire in the temperate forests of Patagonia, Argentina

Article References: Rago, M. M., & Urretavizcaya, M. F. (2026). Understory vegetation development six years after a wildfire in the temperate forests of Patagonia, Argentina. Frontiers in Forests and Global Change, 9, Article 1950264. https://doi.org/10.3389/ffgc.2026.1950264

Image Credits: AI Generated

DOI: 10.3389/ffgc.2026.1950264

Keywords: Understory, vegetation, development, years, wildfire, temperate, forests, Patagonia, Argentina, scientific research

The study area lies in the municipality of Rianxo, where the temperate-oceanic climate delivered an average temperature of 15.7 degrees Celsius and an accumulated precipitation of 1,774 liters per square meter in 2024. The parent material is mainly granitic, and the soils are mostly classified as Leptosols and Umbrisols. These forests are communal properties, owned collectively by villagers, and the sampling was carried out in collaboration with forest owner associations across five forest communities, from Campelo Vilar e Cerqueiras to Leiro, at altitudes ranging from 50 to 485 meters above sea level. In each of the 54 stands, the team collected 10 subsamples along a zig-zag transect, compositing them into a single sample per plot from the 0 to 20 centimeter soil layer in the summer of 2024.

Galician forest soils are, in general, acidic, rich in organic matter and poor in phosphorus. The measurements confirmed this regional signature: pH values ranged between 4.63 and 5.6, soil organic matter between 12.1 and 20.9 percent, nitrogen between 0.41 and 0.69 percent, and extractable phosphorus between just 4.0 and 8.4 milligrams per kilogram. The researchers attribute these properties primarily to the humid climate, which drives intense leaching and acidification, and to the acidic nature of the granitic parent material, rather than to the tree species themselves. Statistically, no significant differences emerged in these solid-phase chemical properties among the different forest covers, a finding the authors link partly to the young age of more than half of the plantations, most of which were less than six years old.

Where the tree species did matter was in soil water content. Soils under eucalyptus and birch plantations were the driest, averaging 13 and 14 percent respectively, while soils under shrublands held the most water at 27 percent on average, with statistically significant differences. The intermediate values fell between 19 percent under walnut and 25 percent under pine. The ability of eucalyptus to extract large amounts of soil water is well documented, although some authors argue that eucalyptus water depletion is more a myth tied to poor plantation management than an inherent trait of the trees. Birch, meanwhile, has been shown to deplete topsoil moisture compared with conifers such as spruce. Both the birch and eucalyptus stands in this study were established over shallow soils of roughly 50 centimeters that had been burnt by a wildfire in 2019, and the authors suggest that the fire disturbance, the soil management for tree establishment, or the low organic matter content, which reduces water retention, could all explain the dry conditions. Indeed, the team detected a significant positive correlation between soil water content and soil organic matter.

The most striking result concerns microbial respiration, the rate at which soil organisms release carbon dioxide as they decompose organic matter. Soils under walnut plantations showed the highest respiration rates, averaging 1,440 plus or minus 97 parts per million of carbon dioxide per gram, while soils under eucalyptus showed the lowest, at 537 plus or minus 211 parts per million per gram. When the values for all deciduous broadleaf species were pooled together, respiration under eucalyptus was significantly lower than under the deciduous forests, with the coniferous pine values falling in between. Soil respiration correlated positively with soil organic matter, total nitrogen and total carbon, and walnut soils happened to contain the highest organic matter content at 20.9 percent, while eucalyptus soils had the lowest at 12.1 percent.

The walnut result carries an intriguing biochemical twist. Walnut leaf litter is rich in phenolic compounds that can inhibit Gram-positive bacteria but leave fungi unaffected, and fungi are the main drivers of respiration in forest soils. This selective pressure could favor a fungal-dominated community and boost carbon dioxide efflux. The eucalyptus result, by contrast, may reflect a different mechanism: previous studies have described a decrease in fungal dominance within eucalyptus plantations, which could explain the suppressed respiration rates. The eucalyptus plots had all been burnt in 2019, whereas the walnut plots had no recent fire history, but meta-analyses suggest that total soil respiration generally recovers to pre-fire values within about five years, and around three years for temperate forests, making the fire explanation less conclusive.

For the pine plantations, which represented the largest group with 30 samples, the researchers compared respiration across stands of different ages but found no significant differences, although average values tended to decline with tree longevity, from 991 plus or minus 69 parts per million per gram in 2 to 4 year old stands to 774 plus or minus 162 parts per million per gram in stands aged 40 to 45 years. A similar age-related decline has been reported in other coniferous plantations. The team also measured the activity of beta-glucosidase, a key enzyme in the carbon cycle that completes the final step of cellulose hydrolysis by converting cellobiose to glucose, but detected no significant differences among the forest covers, with average values ranging from 60 plus or minus 5 micrograms of p-nitrophenol per gram per hour under walnut to 31 plus or minus 15 under shrublands. The authors suggest that the limited variability in edaphic properties and the young age of most stands may explain the lack of differentiation in this enzyme activity.

Aluminium emerged as another defining feature of these soils. Exchangeable aluminium concentrations averaged between 4.7 and 7.43 centimoles per kilogram, representing between 63 and 90 percent saturation of the exchange complex, with practically all samples exceeding 60 percent saturation, a threshold indicative of alic soils that can limit plant growth. The highest saturation values appeared under shrublands at 90 percent, pines at 86 percent and chestnut at 83 percent, although these differences were not statistically significant. Despite this potentially toxic aluminium load, timber production in Galicia remains high within the temperate-humid region, likely because soil organic matter complexes aluminium into less toxic forms, and anions such as sulfate and fluoride can also bind aluminium and reduce its toxicity. The soils under chestnut, shrubland and pine showed the lowest concentrations of exchangeable calcium and magnesium, possibly reflecting the high demand these species place on these base cations to cope with aluminium stress, and the team detected a strong correlation between exchangeable calcium and magnesium across their samples.

When all the physicochemical and biological properties were analyzed together using redundancy analysis, no structural differences between forest covers were detected. The permutation test revealed that stand age was the only significant factor affecting soil properties, while wildfire events were marginally significant. Community location, altitude, tree species, parental rock and soil depth had no significant effect. The first component of the analysis explained 21.1 percent of the variability and was related to soil respiration, higher in samples with greater organic matter content. The authors acknowledge that their initial hypothesis, that tree species would drive the biggest differences between native broadleaf species and intensive plantations, was not fulfilled, most likely because the different ages of the stands acted as a confounding factor, and because the analyses were restricted to the solid soil phase, which is less sensitive to change than the soil solution.

The implications reach far beyond Galicia. Forest soils are crucial carbon sinks, both above and below ground, yet the soil section is still sometimes excluded from carbon pool estimations despite the enormous amount of carbon stored in it. As climate change sharpens the urgency of maximizing the carbon that healthy forest soils can fix, the finding that which tree species are cultivated measurably alters soil microbial respiration should be considered when elaborating forestry exploitation plans. Soils under eucalyptus exhibited the lowest values for both moisture and microbial respiration, while broadleaf deciduous species generally supported higher microbial activity through greater litter inputs and root exudation. The authors call for further research integrating microbial community analysis with functional assessments, alongside evaluating long-term wildfire and management impacts, to guide forest management under specific edapho-climatic conditions in a warming world.

Subject of Research: Forest soil science

Article Title: Effect of Different Tree Plantations on the Chemical Properties and Microbial Activity in Galician Forests Soils

Article References: Barreiro, A., Míguez-González, A., Cela-Dablanca, R., Díaz-Raviña, M., Núñez-Delgado, A., Fernández-Sanjurjo, M. J., & Álvarez-Rodríguez, E. (2025). Effect of Different Tree Plantations on the Chemical Properties and Microbial Activity in Galician Forests Soils. Spanish Journal of Soil Science, 15, Article 14988. https://doi.org/10.3389/sjss.2025.14988

Image Credits: AI Generated

DOI: 10.3389/sjss.2025.14988

Keywords: forest soils, soil respiration, carbon sink, eucalyptus, soil microbiology, forestry management, Galicia, wildfire, Effect, Different, Tree, Plantations

The research, published in Environmental Monitoring and Assessment, was conducted by Salih Malkoçoğlu of Muğla Sıtkı Koçman University and Ergün Kahveci of Tokat Gaziosmanpaşa University. Their study site could hardly be more timely or more representative of the Mediterranean’s fire problem. In 2025, the Köyceğiz-Akköprü fire swept through a forest dominated by Pinus brutia, the Turkish red pine, a species that anchors vast stretches of the eastern Mediterranean’s fire-adapted landscapes. Rather than relying solely on satellite pixels, the researchers walked the burned ground themselves, laying down a dense network of measurement transects that recorded what was actually covering the soil, point by point.

The field protocol was meticulous. In each of 73 sampling plots, the team established two orthogonal transects, each 10 meters long, and recorded surface conditions at every 1-meter interval. That effort produced 1,601 individual point observations, each assigned to one of seven mutually exclusive surface-cover categories. This kind of transect-based ground cover measurement is a standard technique in fire effects monitoring, but what makes the new study distinctive is how directly it confronts the satellite record. For every plot, the researchers computed three Sentinel-2-derived indices: the differenced normalized burn ratio, known as dNBR; its relativized cousin, RdNBR; and the normalized difference vegetation index, NDVI.

Each of these indices has a long pedigree. dNBR, formalized by Key and Benson for the U.S. Forest Service’s FIREMON program, compares pre-fire and post-fire reflectance in the near-infrared and shortwave-infrared bands, where healthy vegetation and charred ground diverge most sharply. RdNBR, introduced by Miller and Thode in 2007, rescales that difference by pre-fire vegetation density, in principle allowing severity to be compared across stands that were structurally different before the fire. NDVI, dating back to Tucker’s foundational work in 1979, tracks the red and near-infrared contrast that signals photosynthetically active green vegetation. All three are staples of post-fire assessment, and all three are routinely treated as proxies for burn severity.

The regression models built in the new study tell a very different story. NDVI emerged as the index most tightly coupled to what was actually on the ground after the fire: its model had the highest explanatory power, with an adjusted R-squared of 0.439, and it was positively associated with live cover, carrying a standardized coefficient of +0.369. In plain terms, the greener the ground cover measured along the transects, the higher the NDVI recorded from orbit. That is exactly what one would hope for from a vegetation index, and it confirms that NDVI is picking up genuine early recovery signals, the resprouting shrubs, herbaceous flushes, and surviving understory that appear in the first growing season after a Mediterranean fire.

dNBR, by contrast, refused to behave as a pure measure of burn severity. Its strongest associations were not with post-fire surface conditions at all, but with pre-fire tree cover and with slope. The index, in other words, was largely encoding the structural and topographic context that existed before the flames arrived. This finding resonates with a growing body of literature, including work by Viedma and colleagues in southeastern Spain, showing that pre-fire vegetation and terrain often dominate the spectral signal that dNBR registers. A satellite index that is supposed to describe what the fire did may, in heterogeneous Mediterranean terrain, be describing mostly what was there to burn and where it stood on the landscape.

Perhaps the most intriguing result concerns RdNBR, the relativized index designed specifically to correct for pre-fire conditions. Instead of cleanly isolating fire effects, RdNBR showed a negative association with needle litter. The researchers interpret this as evidence that relative fire severity indices remain sensitive to residual organic cover, the layers of needles, duff, and litter that survive or accumulate after a burn. Because RdNBR normalizes by pre-fire vegetation, patches that retained substantial organic ground cover can register as less severely burned even when the fire’s actual effects on soils and surviving biota were substantial. The very adjustment meant to make the index more comparable across sites appears to entangle it with the organic residue that Mediterranean pine forests characteristically leave behind.

The team did not stop at the first round of models. Because ecological measurements taken across a landscape are rarely statistically independent, nearby plots tend to resemble one another, the researchers ran spatial robustness analyses that accounted for residual spatial dependence in their data. The principal associations survived. NDVI remained tied to live cover, dNBR to pre-fire structure and topography, and RdNBR to residual organic components. This methodological rigor matters, because spatial autocorrelation is a well-known source of inflated confidence in landscape-scale regression studies, a point emphasized in the geographical ecology literature since Diniz-Filho and colleagues’ influential critique of so-called red herrings in spatial analysis.

The practical upshot is a reframing of how satellite indices should be used in post-fire assessment. Rather than treating dNBR, RdNBR, and NDVI as three interchangeable dials reading the same underlying quantity of burn severity, the study shows they are complementary instruments, each tuned to a different ecological component of the post-fire landscape. dNBR, in this Mediterranean setting, functions largely as a recorder of pre-fire structural and topographic context. NDVI functions as a genuine early-recovery monitor, responsive to the living cover that determines erosion resistance, seedling establishment, and habitat recovery. RdNBR sits in between, its relativization making it sensitive to the residual organic layer that governs soil protection and hydrological response. Managers who read a single index map and draw conclusions about ecological damage or recovery may therefore be reading one channel of a multi-channel signal and mistaking it for the whole broadcast.

The study also demonstrates a practical field-reference workflow that could be adopted widely. By pairing systematic transect-based ground cover measurements with freely available Sentinel-2 imagery, the researchers show that the ecological meaning of spectral indices can be calibrated cheaply and repeatably, without exotic instrumentation. As Mediterranean-type regions face longer fire seasons and larger, more severe burns, as argued in recent calls for a paradigm shift in wildfire management, the demand for rapid, ecologically honest post-fire assessments will only grow. This study’s message is both a caution and a gift: the satellites are telling the truth, but each index tells a different truth, and only by grounding them in measured ground cover can fire ecologists decode which one they are hearing.

Subject of Research: Ecological interpretation of Sentinel-2 spectral indices for post-fire assessment in a Mediterranean Pinus brutia forest

Article Title: Linking transect-based field observations with Sentinel-2 indices to characterize post-fire conditions in a Mediterranean Pinus brutia forest

Article References: Malkoçoğlu, S., & Kahveci, E. (2026). Linking transect-based field observations with Sentinel-2 indices to characterize post-fire conditions in a Mediterranean Pinus brutia forest. Environmental Monitoring and Assessment, 198(11), 1207. https://doi.org/10.1007/s10661-026-16023-4

Image Credits: AI Generated

DOI: 10.1007/s10661-026-16023-4

Keywords: Sentinel-2, dNBR, RdNBR, NDVI, burn severity, wildfire, Pinus brutia, Mediterranean forests, transect sampling, ground cover, remote sensing, fire ecology

The scale of cropland loss in the region is striking. Over the last forty years, more than four million hectares of farmland have disappeared across the Western United States, retired, converted, or abandoned as drought, water scarcity, and economic pressures reshaped agriculture. Within the specific zones where wildfires and cropland converge, the study found that approximately 10.6 million acres of irrigated land have transitioned to other uses since 1985, an area roughly equivalent to the size of Switzerland. Much of that land has given way to scrubland and other low-lying vegetation that burns more readily than well-watered fields. About twenty percent of the converted acreage was developed into human communities, concentrated around metropolitan areas, introducing new ignition sources and complicating suppression efforts.

To quantify how cropland influences where fires stop, the team assembled an unusually comprehensive dataset: wildfire perimeter records for nearly 10,000 fires spanning 1985 to 2024. By overlaying these perimeters with land-use maps, they could ask a deceptively simple question — when a wildfire reaches a boundary between different land types, where does it tend to halt? The answer was consistent across the region. Compared with wildlands, forests, and urban areas, cropland was significantly less likely to end up inside a burn scar. Across nearly four decades of fire records, cropland was 1.3 to 5 times more strongly associated with where fires stopped than other land types, with only barren land performing as an equally effective fire barrier.

The mechanism behind this buffering effect is rooted in basic fire physics. Actively irrigated crops retain substantial moisture in their tissues and in the soil beneath them, raising the fuel moisture content well above the thresholds at which vegetation ignites and carries flame. Moist fuels absorb heat that would otherwise preheat adjacent material, suppressing the spread of fire across the field boundary. Beyond moisture, the geometry of farmland matters: wide, open expanses of low-stature vegetation lack the vertical continuity that allows flames to climb into shrubs and tree canopies. These open spaces also serve a tactical role during active incidents, offering staging points for firefighters and equipment in landscapes where access can otherwise be dangerously limited.

The buffering effect is strongest where irrigation schedules overlap with fire season, a pattern the researchers observed in some of the West’s most productive agricultural regions: California’s Central Valley, Washington’s Columbia Basin, and Idaho’s Snake River Plain. In these landscapes, peak water application coincides with the hottest, driest months, meaning fields are at their most fire-resistant precisely when the surrounding wildlands are at their most flammable. Satellite imagery from the study makes the pattern visually unmistakable, with irrigated fields appearing as unburned red islands within blackened fire perimeters.

For Gordon, a hydrologist whose work has long focused on agricultural water use, the findings reframed her own discipline. Water researchers tend to concentrate on how much water crops consume and how much can be saved by reducing or changing production in drought-stricken areas, she explained, but far less attention has gone to what happens after the land use changes. Collaborating with wildfire managers made clear that drought adaptation strategies which alter cropland can influence how fire moves through the landscape. In her words, out in the West, there is no longer the luxury of thinking about just one hazard at a time. The study’s central argument is that water conservation and wildfire risk reduction should be managed jointly rather than in isolation.

This matters because the most widely used water-saving strategies are precisely the ones that remove irrigated land from production. Targeted and voluntary idling of cropland is a practical, politically feasible tool for reducing agricultural water demand, and it has been deployed repeatedly during drought emergencies. But the new analysis shows that removing cropland eliminates its fire-buffering advantages regardless of what the land becomes next, whether that is dry scrub, grassland, or suburban development. A field retired to save water in one year may become a corridor for fire spread in the next, and the tradeoff is rarely accounted for in drought planning documents.

The authors argue that existing institutional machinery could be adapted to close this gap. They propose supporting structures that integrate water and wildfire planning, developing methods to evaluate transition-specific water savings against the wildfire risk they create, and using established agricultural conservation programs as planning platforms. One candidate is the U.S. Department of Agriculture’s Conservation Reserve Program, which already offers financial incentives to landowners who convert environmentally sensitive land out of production. Expanding such programs to weigh fire-buffering value alongside their existing criteria, the researchers suggest, would allow policymakers to identify where retiring farmland delivers the greatest water savings at the lowest cost to community fire resilience.

Gordon emphasized that the findings do not admit a simple answer. The complexity cannot be reduced to slogans like fire is bad or cropland is water intensive, she cautioned, expressing hope that the work can help identify where the trade-offs are steepest when communities face compounding hazards. That nuance is essential for a region where every option carries costs: keeping land in production consumes scarce water, retiring it may accelerate fire spread, and converting it to housing places more people and ignition sources in harm’s way. The goal, the researchers suggest, is not to freeze agricultural land use in place but to make each transition with a clear-eyed view of its consequences for both water budgets and fire behavior.

The study is the first analysis of its kind for the Western United States, but its conclusions align with earlier European research on the fire-buffering value of croplands, lending the findings broader credibility. The team now hopes to extend the work by quantifying wildfire risk for different specific types of cropland conversion, distinguishing, for example, between land that reverts to scrub and land that becomes subdivisions. Such refined projections could give Western communities a practical planning tool for a future defined by both less water and larger, more severe wildfires — a future in which every acre of irrigated farmland may matter not only for food and water, but for the fire lines drawn on the map.

Subject of Research: The tradeoffs between drought adaptation through cropland loss and wildfire resilience in the Western United States

Article Title: Wide-scale cropland loss has consequences for wildfire resilience in the American West, new research finds

Article References: Wide-scale cropland loss has consequences for wildfire resilience in the American West, new research finds. (n.d.). Original publication

Image Credits: AI Generated

DOI: Not provided

Keywords: wildfire, cropland, drought, irrigation, American West, water conservation, land use change, fire behavior, Environmental Research Letters, Desert Research Institute, urbanization, fire resilience