Widespread Fires Research Articles

Weighing Policy Effectiveness Through Recent Forest Fire Status

Forest fires pose a great threat to the global ecological environment as well as human life and the safety of property. Formulating effective policies for preventing forest fires is not only a scientific concern but also an urgent need for government management. Canada and China both have extensive forest areas but have different fire management strategies. Canada primarily focuses on fire suppression while China pays more attention on fire prevention. This difference led to significant discrepancies in the forest fire regimes between the two countries, providing an opportunity to explore the impact of fire management policies on forest fire. By analyzing the fire occurrences in Canada and China since 1990, combining the fire prevention funds and fire management strategies, this paper discussed the influence of different policies on fire occurrence. Previously, Canada’s forest suppression strategy has been widely recognized internationally, but recent widespread fires indicate that its fire management policy may still require further improvement to cope with future global warming. Although China’s fire prevention strategy can effectively control current forest fires, the lack of fundamental theories on forest fires and the backwardness of fire prevention technology and equipment may increase the likelihood of major forest fires in the future. As global warming continues to intensify in the future, the length of the forest fire season and the intensity of fires will increase, making it urgent to develop more effective forest fire prevention and suppression policies to achieve sustainable development.

CONTEXTUAL REANALYSIS OF THE ARCHITECTURAL FORM AND SOCIO-ECONOMIC STATUS OF THE PANAGIA HOUSES AT MYCENAE

The Panagia Houses, one of the building complexes at Mycenae, located to the south-west of the Citadel, were interpreted by the excavators as a group of three independent units. They were constructed and occupied during the Late Helladic (LH) IIIB phase, with two main phases distinguishable in the archaeological record, followed by a reoccupation phase. Careful analysis of the archaeological data published by Mylonas-Shear, which focused on the arrangement of individual units, formality of layout, access and movement patterns, and visibility, suggests that the group should be interpreted rather as a single complex, developed during the period of the maximum expansion of the settlement. The building was gradually expanded to form an extended household, with primary living space surrounded by a number of additional rooms for storage, work and habitation. It was composed of a rectangular main unit, surrounded by an extension formed around a small inner courtyard. The movement between the two levels was organised through a system of connected rooftops, with trapdoors and staircases ensuring access to the various rooms of the complex. During the LH IIIB2 Early phase, Mycenae was hit by a devastating earthquake. Much of the town was left in ruin, but the Panagia Houses were rebuilt, although in a smaller form, with the main unit abandoned and the courtyard inside the extension transformed into the main room of the complex. The status of the complex probably changed, but it was still inhabited by a middle-class family, who possessed a number of valuables and took part in the palatial mobilisation system. The household probably suffered in a widespread fire which destroyed Mycenae at the end of LH IIIB. Its remains were then used as two small dwellings by the survivors of the catastrophe. The history of the complex reflects the changing vicissitudes of the Lower Town of Mycenae.

Fire history in northern Sierra Nevada mixed conifer forests across a distinct gradient in productivity

BackgroundUnderstanding the role of fire in forested landscapes is fundamental to fire reintroduction efforts, yet few studies have examined how fire dynamics vary in response to interactions between local conditions, such as soil productivity, and more broadscale changes in climate. In this study, we examined historical fire frequency, seasonality, and spatial patterning in mixed conifer forests across a distinct gradient of soil productivity in the northern Sierra Nevada. We cross-dated 46 different wood samples containing 377 fire scars from 6 paired sites, located on and off of ultramafic serpentine soils. Forests on serpentine-derived soils have slower growth rates, lower biomass accumulation, and patchier vegetation than adjacent, non-serpentine sites. Due to these differences, we hypothesized that historical fire frequency and spatial extent would be reduced in mixed conifer forests growing on serpentine soils.ResultsFire scars revealed a history of frequent fire at all of our sites (median composite interval: 6–22.5 years) despite clear differences in soil productivity. Fire frequency was slightly shorter in more productive non-serpentine sites, but this difference was not consistently significant within our sample pairs. While fires were frequent, both on and off of serpentine, they were also highly asynchronous, and this was largely driven by differing climate–fire relationships. Fires in more productive sites were strongly associated with drought conditions in the year of the fire, while fires in less productive serpentine sites appeared to be more dependent on a cycle of wet and dry conditions in the years preceding the fire. Widespread fires that crossed the boundary between serpentine and non-serpentine were associated with drier than normal years.ConclusionsIn our study, fine-scale variation in historical fire regime attributes was linked to both bottom-up and top-down controls. Understanding how these factors interact to create variation in fire frequency, timing, and spatial extent can help managers more effectively define desired conditions, develop management objectives, and identify management strategies for fire reintroduction and forest restoration projects.

Changes in aerosol properties at the El Arenosillo site in Southern Europe as a result of the 2023 Canadian forest fires

From the beginning of May 2023 to the end of August 2023, the Northern Hemisphere experienced significant wildfire activity with the most widespread fires occurring in Canada. Forest fires in Canada destroyed more than 15.6 million hectares of forests. These wildfires worsened air quality across the region and other parts of the world. The smoke reached southern Europe by the end of June 2023. To better understand the consequences of such forest fires far from the site of origin, aerosol optical, microphysical and radiative properties were analyzed during this event for southern Europe using data from the Visible Infrared Imaging Radiometer Suite (VIIRS), TROPOspheric Monitoring Instrument (TROPOMI), and Aerosol Robotic Network (AERONET). TROPOMI aerosol index (AI) and the carbon monoxide (CO) product confirm that the smoke originated directly from these forest fires. AERONET data from the El Arenosillo site in southern Spain showed maximum aerosol optical depth (AOD) values on June 27 reached 2.36. Data on Angstrom Exponent (AE), aerosol volume size distribution (VSD), single scattering albedo (SSA), fine mode fraction (FMF), volume particle concentration, effective radius (REff), absorption AOD (AAOD), extinction AE (EAE) and absorption AE (AAE) showed that fine-mode particles with carbonaceous aerosols contribution predominated in the atmosphere above the El Arenosillo site. Direct aerosol radiative forcing (DARF) at the top (DARFTOA) and bottom of atmosphere (DARFBOA) were −103.1 and −198.93 Wm−2, respectively. The atmospheric aerosol radiative forcing (DARFATM) was found to be 95.83 Wm−2 and with a heating rate 2.69 K day−1, which indicates the resulting warming of the atmosphere.

Near-term fire weather forecasting in the Pacific Northwest using 500-hPa map types

Background Near-term forecasts of fire danger based on predicted surface weather and fuel dryness are widely used to support the decisions of wildfire managers. The incorporation of synoptic-scale upper-air patterns into predictive models may provide additional value in operational forecasting. Aims In this study, we assess the impact of synoptic-scale upper-air patterns on the occurrence of large wildfires and widespread fire outbreaks in the US Pacific Northwest. Additionally, we examine how discrete upper-air map types can augment subregional models of wildfire risk. Methods We assess the statistical relationship between synoptic map types, surface weather and wildfire occurrence. Additionally, we compare subregional fire danger models to identify the predictive value contributed by upper-air map types. Key results We find that these map types explain variation in wildfire occurrence not captured by fire danger indices based on surface weather alone, with specific map types associated with significantly higher expected daily ignition counts in half of the subregions. Conclusions We observe that incorporating upper-air map types enhances the explanatory power of subregional fire danger models. Implications Our approach provides value to operational wildfire management and provides a template for how these methods may be implemented in other regions.

Teotihuacan ancient culture affected by megathrust earthquakes during the early Epiclassic Period (Mexico)

Teotihuacan was one of the thriving cultures in the Mesoamerica pre-Hispanic times, located in the Central Valley of Mexico. The city-state was a dominant centre point during the Classic period and its influence affected other contemporaneous cultures. Around the year 550 CE, a continuous decrease in urban population and selective building destruction was noted, accompanied by widespread fire. The layout of the city is identified by an avenue that articulates the political-administrative and religious centres, with such significant and impressive buildings as the Pyramid of the Sun, the Pyramid of the Moon and the Temple of Feathered Serpent. A systematic analysis of building damage in the pyramids reveals several Earthquake Archaeological Effects, (EAEs) potentially related to seismic loading. A damage pattern compatible with a strong ground shaking was also identified in the west staircase of the Old Temple of the Feathered Serpent, in the first rows of the west staircase of the Adosada platform (New Temple), and in the Pyramid of the Sun. In total, five ancient earthquakes have been determined from the damage, dated from the Tzacualli cultural period (1–100 CE), to the Xolalpan – Metepec period (450–550 CE). Unfortunately, this methodology does not determine the earthquake source. Therefore, we consider the possibility that repetitive megathrust earthquakes (Mw > 8.5) from the Middle American Trench (Pacific coast) could be responsible for the spatial pattern of the building damage. This proposal does not conflict with other existing theories for the Teotihuacan abrupt collapse, considering that the sudden overlapping of natural disasters like earthquakes could increase internal warfare (uprising), and civil unrest.

Integrated fire management in a tropical biosphere reserve: Achievements and challenges

Wildfires are among the most critical threats to tropical rainforests. In the Selva El Ocote Biosphere Reserve in the Mexican state of Chiapas, vast rainforest areas suffered destruction by fires in 1998 and 2003. However, there have been no more widespread fires, and previously burnt areas have been recovering. The present study analyses the integrated fire management processes implemented in the reserve. It includes 19 expert interviews and a survey applied to 274 inhabitants of local communities. It argues that the successful prevention of further adverse wildfire events is related to a fire management approach, which emphasizes cultural and physical fire prevention and incorporates strong participation by local communities. The communities have established internal agreements to mitigate wildfire risk. Thus, the reserve might serve as an example of how integrated and cultural fire management can be applied in practice. However, these achievements face challenges, mainly due to budget cuts, changing governmental priorities, and the crisis of the rule of law in Mexico. An event that particularly impacted fire management practices in the area in recent years was the implementation of the federal government's Sembrando Vida (“Planting Life”) program. First, it led to deforestation and the provocation of wildfires but afterwards it seems to have induced the abandonment of agricultural burning by a considerable percentage of local farmers.

The Bronze Age Destruction of Jericho, Archaeology, and the Book of Joshua

The ancient city of Jericho, located at the archaeological site of Tell es-Sultan west of the Jordan River and adjacent to the Ein es-Sultan spring on the edge of modern Jericho, has often been associated with the biblical city of Jericho and the story found in the book of Joshua. The identification of Jericho with Tell es-Sultan is not disputed, and numerous excavation teams have affirmed Tell es-Sultan as Jericho. While excavations have also uncovered the fiery destruction of a walled city at Jericho, the date of the fall of Bronze Age Jericho and the association of this destruction with the narrative in the book of Joshua have been a point of disagreement among archaeologists for more than a century. The first excavations at Jericho (Tell es-Sultan) occurred in 1868 under the direction of Charles Warren, followed by soundings conducted by FJ Bliss in 1894, the expeditions of the years 1907–1909 and 1911 by Ernst Sellin and Carl Watzinger, the excavations of 1930–1936 directed by John Garstang, the 1952–1958 project of Kathleen Kenyon, brief excavations by Shimon Riklin in 1992, and the most recent excavations and restorations by the joint Italian–Palestinian team from 1997 to 2000 under Nicolo Marchetti and Lorenzo Nigro, followed by the 2009–2017 seasons directed by Jehad Yasin, Hamdan Taha, and Lorenzo Nigro. Although there is a significant deviation in views over the exact date of the destruction and abandonment, archaeological analyses of Jericho generally agree on the manner in which the city met its end, including a widespread fire, collapsed mudbrick walls, burning of the stored grain, and abandonment. However, assessing all of the archaeological data from Jericho IVc, both new and old, including pottery wares, Egyptian scarabs, a cuneiform tablet, stratigraphic analysis, and radiocarbon samples, allows a more definitive historical reconstruction concerning the chronology of the destruction of Jericho and its connections to the biblical narratives.

Energy Expenditure of Disaster Relief Operations Estimated Using a Tri-Axial Accelerometer and a Wearable Heart Rate Monitor.

The management of nutrition, food, and health for disaster relief personnel is one of the crucial aspects for carrying out effective rescue activities during large-scale natural disasters, such as a big earthquake, flooding, and landslide following heavy rainfall or man-made disasters, such as widespread fire in industrial areas. Rescue workers, such as fire fighters and rescue teams who work on the disaster relief operations, have to work long, hard, and irregular hours that require energy (both intake and expenditure), with especially altered eating patterns. Reliable estimates of the energy expenditure (TEE) for such disaster relief operations have not been fully established. Here, we propose to clarify the energy expenditure for each type of large-scale disaster activity conducted by fire fighters. Thirty fire fighters (survey participants in this research) who participated in the simulation training of large-scale disaster activities wore tri-axial accelerometers and heart rate monitors during training; and, post-training, 28 fire fighters submitted complete activity record tables. An estimation formula combining tri-axial accelerometer and heart rate monitor data was used. Additionally, energy expenditure per hour (excluding resting energy expenditure: REE) (per average body weight of participants) was calculated for 10 types of large-scale disaster response activities. We propose utilization of these data as a reference value for examining the TEE of firefighting and rescue operations in future large-scale disasters.

Climate Change as a Threat to Health: Family Medicine Call to Action and Response.

Climate change presents existential threats to human health and the sustainability of life on earth.[1][1]-[2][2] Increased global temperatures have resulted in more frequent and extreme weather events, widespread fires, and catastrophic flooding, which in turn affect food production, air quality,

Siberian carbon sink reduced by forest disturbances

Siberian forests are generally thought to have acted as an important carbon sink over recent decades, but exposure to severe droughts and fire disturbances may have impacted their carbon dynamics. Limited available forest inventories mean the carbon balance remains uncertain. Here we analyse annual live and dead above-ground carbon changes derived from low-frequency passive microwave observations from 2010 to 2019. We find that during this period, the carbon balance of Siberian forests was close to neutral, with the forests acting as a small carbon sink of $$+ 0.02_{ + 0.01}^{ + 0.03}$$ PgC yr−1. Carbon storage in dead wood increased, but this was largely offset by a decrease in live biomass. Substantial losses of live above-ground carbon are attributed to fire and drought, such as the widespread fires in northern Siberia in 2012 and extreme drought in eastern Siberia in 2015. These live above-ground carbon losses contrast with ‘greening’ trends seen in leaf area index over the same period, a decoupling explained by faster post-disturbance recovery of leaf area than live above-ground carbon. Our study highlights the vulnerability of large forest carbon stores in Siberia to climate-induced disturbances, challenging the persistence of the carbon sink in this region of the globe. Carbon sequestration by Siberian forests has been low over the past decade due to disturbances that have decreased live biomass and increased dead wood, according to passive microwave observations.

Rimbo: Hutan Bagi Orang Rimba di Taman Nasional Bukit Dua Belas

The tropical rain forest area in Sumatra is not spared from extensive exploitation that has undergone changes in the last decade. The impact of degradation caused by the exploitation of oil palm land and large-scale clearing and widespread fires has caused the forest to be depleted. The depletion of the forest has disturbed the local community in it, namely the Orang Rimba who have been inhabiting lowland forests in the TNBD (Bukit Dua Belas National Park) area.This study uses an ethnoecological approach to describe and explain the Orang Rimba knowledge system to the forest, the relationships built for survival and the importance of the forest and the survival of the Orang Rimba.This research shows that Rimbo is a place and living space for Orang Rimba. So there is a classification of Rimbo for Orang Rimba which divides it into two, namely Jungle/Forest (Rimbo) and Tana (Land). The forest is divided into Rimbo, Bungaron, Ranah, Sesap and Belukah, Benuaron, Lalot'on. Meanwhile, Tana is divided into Tana Dewo, Tana Pasuron and Tana Bediom and Tana Perano'an and Ladong. On the basis of the division of Rimbo, the Orang Rimbo refer to their belief that nature is divided into Halom Nio and Halom Dewo. So for the Orang Rimba, Rimbo is a culture and survival in carrying out life.

Ecological legacies of past fire and human activity in a Panamanian forest

Societal Impact StatementTropical forests provide global ecosystem services and harbor much of Earth's terrestrial biodiversity, but the mechanisms driving the patterns of biodiversity remain uncertain. Palms are one of the most abundant and most widely used plant groups, particularly in the Neotropics. Our data highlight how both direct and indirect human influence that occurred decades to hundreds of years ago can affect the abundances of palm species in modern tropical forests. Our results highlight that biodiversity is dynamic, and changes through time, and that human activities can affect species composition for centuries in tropical forests.Summary Human activities over the past decades and centuries, including fire, cultivation, and forest opening, may have left ecological legacies that persist in modern tropical forests, particularly among palms. We investigated whether past human activities affected modern palm abundances in a well‐studied plot located in a tropical semievergreen forest of Panama. We analyzed soil cores for charcoal to reconstruct past fire events and phytoliths to reconstruct past vegetation changes. We dated as many charcoal fragments as possible to place a temporal framework on past fire events. Our analysis documented widespread fires that occurred 600–900 years ago across the plot. Oenocarpus mapora increased in abundance as a result of these fires, though other palms did not. A subsequent increase in O. mapora occurred later in the relative absence of fire and was likely due to game hunting during the construction of the Panama Canal. Our results showed that the enrichment of O. mapora was determined by disturbance characteristics (e.g., timing, type, and intensity), but the persistence of increased abundances was likely determined by traits (life history characteristics). These data highlight the complexity of human–environment interactions and how they can persist for centuries in settings with long‐lived trees such as tropical forests. These data highlight the importance of adding a historical context to further understand modern ecological patterns and processes.

Integrating machine learning, remote sensing and citizen science to create an early warning system for biodiversity

Societal Impact StatementThe development and implementation of conservation actions that address urgent threats to biodiversity across the globe require large amounts of historic and current data. Machine learning approaches offer the tools to process, analyse and interpret large data sets, giving insights into trends and guiding evidence‐based allocation of limited resources to maximise positive biodiversity outcomes. Here we describe how data acquired from remote sensing, citizen science and other monitoring approaches could feed in near‐real time into an early warning system for biodiversity that integrates automated red‐listing of species with the identification of priority areas for conservation.SummaryApplication of machine learning approaches is aiding biodiversity conservation and research at a time of rapid global change. Two emerging topics and their data requirements are presented. First, to identify areas of priority protection for preventing biodiversity loss, reinforcement learning is used by training models that take into account human disturbance and climate change under recurrent monitoring schemes. Second, neural networks are used to approximate classification of species into Red List categories of the International Union for Conservation of Nature, offering the possibility of real‐time re‐classification after events such as widespread fires and deforestation. We discuss how the identification of areas and species most at risk could be integrated into an ‘early warning system’ based on climatic monitoring, remotely sensed land‐use changes and near‐real time biological and threat data from citizen science initiatives. Such system would help guide actions to prevent biodiversity loss at the speed required for effective conservation.

Seasonal variations in fire conditions are important drivers in the trend of aerosol optical properties over the south-eastern Atlantic

Abstract. From June to October, southern Africa produces one-third of the global biomass burning (BB) emissions by widespread fires. BB aerosols are transported westward over the south-eastern Atlantic with the mid-tropospheric winds, resulting in significant radiative effects. Ascension Island (ASI) is located midway between Africa and South America. From June 2016 to October 2017, a 17-month in situ observation campaign on ASI found a low single-scattering albedo (SSA) as well as a high mass absorption cross-section of black carbon (MACBC), demonstrating the strong absorbing marine boundary layer in the south-eastern Atlantic. Here we investigate the monthly variations of critical optical properties of BB aerosols, i.e. SSA and MACBC, during the BB seasons and the driving factors behind these variations. Both SSA and MACBC increase from June to August and decrease in September and October. The average SSA during the BB seasons is 0.81 at 529 nm wavelength, with the highest mean ∼ 0.85 in October and the lowest ∼ 0.78 in August. The absorption enhancement (Eabs) derived from the MACBC shows similar trends with SSA, with the average during the whole of the BB seasons at ∼ 1.96 and ∼ 2.07 in 2016 and 2017, respectively. As the Eabs is higher than the ∼ 1.5 commonly adopted value by climate models, this result suggests the marine boundary layer in the south-eastern Atlantic is more absorbing than model simulations. We find the enhanced ratio of BC to CO (ΔBC/ΔCO, equal to BC/ΔCO as the BC background concentration is considered to be 0) is well correlated with SSA and MACBC, providing a simple way to estimate the aerosol optical characteristics in the south-eastern Atlantic. The exponential function we proposed can approximate SSA and MACBC with BC/ΔCO, and when BC/ΔCO is small it can capture the rapid growth of SSA as BC/ΔCO decreases. BC/ΔCO is influenced by combustion conditions and aerosol scavenging. From the analysis of the location of BB, the primary source fuel, the water content in the fuel, combined with the mean cloud cover and precipitation in the transport areas of the BB plume, we conclude that the increase in BC/ΔCO from June to August is likely to be caused by burning becoming more flaming. The reduction in the water content of fuels may be responsible for the change in the burning conditions from June to August. The decrease in BC/ΔCO in September and October may be caused by two factors, one being a lower proportion of flaming conditions, possibly associated with a decrease in mean surface wind speed in the burning area, and the other being an increase in precipitation in the BB transport pathway, leading to enhanced aerosol scavenging, which ultimately results in an increase in SSA and MACBC.

Population collapse of a Gondwanan conifer follows the loss of Indigenous fire regimes in a northern Australian savanna

Colonialism has disrupted Indigenous socioecological systems around the globe, including those supported by intentional landscape burning. Because most disruptions happened centuries ago, our understanding of Indigenous fire management is largely inferential and open to debate. Here, we investigate the ecological consequences of the loss of traditional Aboriginal fire management on fire-exposed savannas on the Arnhem Plateau, northern Australia, using the fire-sensitive conifer Callitris intratropica as a bio-indicator. We contrast Kakadu National Park, where traditional Aboriginal fire management was severely disrupted during the early twentieth century following Aboriginal relocation to surrounding settlements, and an adjacent Aboriginal estate where traditional Aboriginal fire management endures. Since 2006, traditional Aboriginal fire management at this site has been overlaid by a program of broad-scale institutionalized burning in the early dry season, designed to reduce greenhouse emissions. Using remote sensing, field survey, and dendrochronology, we show that on the Aboriginal estate, C. intratropica populations depend on the creation of a shifting patch mosaic of long unburned areas necessary for the recruitment of C. intratropica. However, the imposition of broad-scale fire management is disrupting this population patch dynamic. In Kakadu, there have been extreme declines of C. intratropica associated with widespread fires since the mid twentieth century and consequent proliferation of grass fuels. Fire management in Kakadu since 2007, designed to increase the size and abundance of patches of unburned vegetation, has not been able to reverse the population collapse of C. intratropica. Our study demonstrates that colonial processes including relocation of Indigenous people and institutional fire management can have deleterious consequences that are nearly irreversible because of hysteresis in C. intratropica population dynamics.

The influence of land-use activities and regional drought on historical fire regimes of Buryatia, Siberia

Every year, millions of hectares burn across Siberia, driven by a combination of warming temperatures, regional drought and human-caused ignitions. Dendrochronology provides a long-term context to evaluate recent trends in fire activity and interpret the relative influence of humans and climate drivers on fire regimes. We developed a 400 year record of fire-scarred trees from 17 sites in pine-dominated forests located southeast of Lake Baikal. Site-level mean fire return intervals (MFIs) ranged from 4 to 27 years for all fires and 8 to 35 years for widespread fires within sites. Sites with the lowest MFI values were located within 1 km of agricultural fields in grassland valleys, suggesting that agricultural burning influenced MFIs at nearby sites. Fire frequency varied over the record, with significantly high values around 1790, from 1865 to 1880, 1948 to 1955 and 1995 to 2005. The increased fire activity corresponded with migration waves to the region and major socio-economic change connected with the establishment and breakdown of the Soviet Union. At broader scales, superposed epoch analysis showed that synchronous fire years were associated with regional drought and precipitation deficits. Wet conditions for 2–3 years prior to the event year were also significant, suggesting that increased moisture promoted growth of understory fine fuels to support more extensive fires across the study area. Although fire frequencies increased during the 20th century, fire–climate relationships weakened, suggesting increased human-caused ignitions may override regional climate drivers. Our dataset presents a continuous record of frequent surface fires over the past 400 years, providing a valuable opportunity to compare dendrochronology-based reconstructions with satellite and documentary records.

Historical trends of degradation, loss, and recovery in the tropical forest reserves of Ghana

ABSTRACT The Upper Guinean Forest region of West Africa, a globally significant biodiversity hotspot, is among the driest and most human-impacted tropical ecosystems. We used Landsat to study forest degradation, loss, and recovery in the forest reserves of Ghana from 2003 to 2019. Annual canopy cover maps were generated using random forests and results were temporally segmented using the LandTrendr algorithm. Canopy cover was predicted with a predicted-observed r2 of 0.76, mean absolute error of 12.8%, and mean error of 1.3%. Forest degradation, loss, and recovery were identified as transitions between closed (>60% cover), open (15–60% cover) and low tree cover (< 15% cover) classes. Change was relatively slow from 2003 to 2015, but there was more disturbance than recovery resulting in a gradual decline in closed canopy forests. In 2016, widespread fires associated with El Niño drought caused forest loss and degradation across more than 12% of the moist semi-deciduous and upland evergreen forest types. The workflow was implemented in Google Earth Engine, allowing stakeholders to visualize the results and download summaries. Information about historical disturbances will help to prioritize locations for future studies and target forest protection and restoration activities aimed at increasing resilience.

Life Stage and Neighborhood-Dependent Survival of Longleaf Pine after Prescribed Fire

Determining mechanisms of plant establishment in ecological communities can be particularly difficult in disturbance-dominated ecosystems. Longleaf pine (Pinus palustris Mill.) and its associated plant community exemplify systems that evolved with disturbances, where frequent, widespread fires alter the population dynamics of longleaf pine within distinct life stages. We identified the primary biotic and environmental conditions that influence the survival of longleaf pine in this disturbance-dominated ecosystem. We combined data from recruitment surveys, tree censuses, dense lidar point clouds, and a forest-wide prescribed fire to examine the response of longleaf pine individuals to fire and biotic neighborhoods. We found that fire temperatures increased with increasing longleaf pine neighborhood basal area and decreased with higher oak densities. There was considerable variation in longleaf pine survival across life stages, with lowest survival probabilities occurring during the bolt stage and not in the earlier, more fire-resistant grass stage. Survival of grass-stage, bolt-stage, and sapling longleaf pines was negatively associated with basal area of neighboring longleaf pine and positively related to neighboring heterospecific tree density, primarily oaks (Quercus spp.). Our findings highlight the vulnerability of longleaf pine across life stages, which suggests optimal fire management strategies for controlling longleaf pine density, and—more broadly—emphasize the importance of fire in mediating species interactions.

Influence of Late Holocene Climate Change and Human Land Use on Terrestrial and Aquatic Ecosystems in Southwest Madagascar

Madagascar’s biota underwent substantial change following human colonization of the island in the Late Holocene. The timing of human arrival and its role in the extinction of megafauna have received considerable attention. However, the impacts of human activities on regional ecosystems remain poorly studied. Here, we focus on reconstructing changes in the composition of terrestrial and aquatic ecosystems to evaluate the impact of human land use and climate variability. We conducted a paleoenvironmental study, using a sediment record that spans the last ∼1,145 years, collected from a lakebed in the Namonte Basin of southwest Madagascar. We examined physical (X-ray fluorescence and stratigraphy) and biotic indicators (pollen, diatoms and micro- and macro-charcoal particles) to infer terrestrial and aquatic ecosystem change. The fossil pollen data indicate that composition of grasslands and dry deciduous forest in the region remained relatively stable during an arid event associated with northward displacement of the Intertropical Convergence Zone (ITCZ) between ∼1,145 and 555 calibrated calendar years before present (cal yr BP). Charcoal particles indicate that widespread fires occurred in the region, resulting from a combination of climate drivers and human agency during the entire span covered by the paleorecord. Following settlement by pastoral communities and the disappearance of endemic megafauna ∼1,000 cal yr BP, grasslands expanded and the abundance of trees that rely on large animals for seed dispersal gradually declined. A reduction in the abundance of pollen taxa characteristic of dry forest coincided with an abrupt increase in charcoal particles between ∼230 and 35 cal yr BP, when agro-pastoral communities immigrated into the region. Deforestation and soil erosion, indicated by a relatively rapid sedimentation rate and high K/Zr and Fe/Zr, intensified between 180 and 70 cal yr BP and caused a consequent increase in lake turbidity, resulting in more rapid turnover of the aquatic diatom community. Land use and ongoing climate change have continued to transform local terrestrial and freshwater ecosystems during the last ∼70 years. The current composition of terrestrial and aquatic ecosystems reflects the legacy of extinction of native biota, invasion of exotic species, and diminished use of traditional land management practices.