New perspectives in fire management in South American savannas: The importance of intercultural governance

Contributions of human cultures to biodiversity and ecosystem conservation

The expansion of globalized industrial societies is causing global warming, ecosystem degradation, and species and language extinctions worldwide. Mainstream conservation efforts still focus on nature protection strategies to revert this crisis, often overlooking the essential roles of Indigenous Peoples and Local Communities (IP&LC) in protecting biodiversity and ecosystems globally. Here we assess the scientific literature to identify relationships between biodiversity (including ecosystem diversity) and cultural diversity, and investigate how these connections may affect conservation outcomes in tropical lowland South America. Our assessment reveals a network of interactions and feedbacks between biodiversity and diverse IP&LC, suggesting interconnectedness and interdependencies from which multiple benefits to nature and societies emerge. We illustrate our findings with five case studies of successful conservation models, described as consolidated or promising 'social-ecological hope spots', that show how engagement with IP&LC of various cultures may be the best hope for biodiversity and ecosystem conservation, particularly when aligned with science and technology. In light of these five inspiring cases, we argue that conservation science and policies need to recognize that protecting and promoting both biological and cultural diversities can provide additional co-benefits and solutions to maintain ecosystems resilient in the face of global changes.

Char and soot records of the Holocene fire history and its implications for climate-vegetation change and human activities within the Guanzhong Basin, southern Loess Plateau, China

Black carbon in sediments has been widely used as a proxy for biomass burning/fire activity to reconstruct fire history and its evolution. Wildfire studies have revealed that different types of black carbon (char and soot) are formed due to changes in combustion efficiency. In this study, we obtained black carbon and its two subtypes, char and soot, from a typical Holocene aeolian loess-paleosol section in the Chilanqiao Ruins within the Guanzhong Basin, southern Loess Plateau, China. Combined with environmental proxies such as magnetic susceptibility, loss on ignition, and geochemical elements, along with AMS14C and optically stimulated luminescence (OSL) dates, we reconstructed the Holocene fire history and its evolution on the southern Loess Plateau at local and regional scales. The findings indicate that the limited vegetation during the relatively dry and cold early Holocene may have inhibited the spread of fires. In the warmer and wetter middle Holocene, there was higher local smoldering fire activity, likely influenced by both wet climatic conditions and an increase in the proportion of woody plants. Additionally, the fire history in relation to human activities at Shang Dynasty (1600-1046 BCE) including land reclamation, house construction, and bronze casting has also been identified. There has been a significant increase in regional flaming fire activity in the late Holocene as a result of drier climate and increased human activity. Notably, the significant increase in regional flaming fire activity since ~1.00 ka can be primarily linked to human-set fires with the usage of gunpowder in frequent wars. This research holds great importance in enhancing our understanding of the long-term interactions among fire activities, climate change and human activities.

Fire seasonality plays a limited role in the reproduction of Anacardium humile A. St.-Hil. in a tropical savanna

Anthropogenic fires are an increasing threat to tropical savannas and their plant populations. In the Brazilian Cerrado, human-made fires at the end of the dry season are replacing natural fires at the beginning of the dry season. Critically, these late burns occur under more intense climate variables. Here, we aimed to understand the potential role of fire seasonality on individuals of Anacardium humile, a widespread Cerrado species of cultural and economic importance. We conducted two prescribed burnings, one at the beginning of the dry season (early burning) and one at the end of the dry season (late burning) when climate variables were remarkably different. We assessed the reproductive responses of A. humile individuals over 4 years and compared individuals from the fire treatments with those from an unburned area (control). The reproductive phenology of A. humile varied over time and was influenced by climate variables. The seasons of different burning had similar impacts on the reproductive phenology of A. humile, and this impact lasted for at least 4 years. While A. humile populations do not depend on fire for reproduction, they produced more flowers and fruits for up to 2 years with the fire treatments. We provide empirical evidence of the role of climate variables on the phenology of A. humile and demonstrate the importance of considering the role of time after fire events. The similar responses of A. humile to fire seasonality show that Cerrado fire management can be more complex than previously thought.

Combining Participatory Mapping and Geospatial Analysis Techniques to Assess Wildfire Risk in Rural North Vietnam

Participatory mapping (PM) is a valuable research tool for assessing fire risk, especially in regions where data are difficult to collect or inconsistent; in such areas, the integration between crowdsourced data and geospatial techniques plays a fundamental role in gathering more consistent and reliable information. This study combines a participatory (community-based) mapping approach with geospatial techniques to assess fire risk in Van Chan district, northern Vietnam, an area where the economy relies mainly on forestry activities. Local stakeholders designed a map of wildfires, which was modelled as a function of a set of physical and socio-economic variables. A fire-probability map of the district was obtained and compared with MODIS data (2000-2020). The results suggest that higher fire probability occurs in areas with lower human pressure, and they provide information on related socio-economic drivers that affect this phenomenon. This study highlights the importance of combining participatory approaches and geospatial techniques to assess fire dynamics and prevent wildfires in terms of understanding and predicting the risks. The involvement of local communities is fundamental to this innovative participatory approach with regard to better supporting decision-making and prevention actions and to developing fire control management guidelines.

The right to burn: barriers and opportunities for Indigenous-led fire stewardship in Canada

Indigenous fire stewardship enhances ecosystem diversity, assists with the management of complex resources, and reduces wildfire risk by lessening fuel loads. Although Indigenous Peoples have maintained fire stewardship practices for millennia and continue to be keepers of fire knowledge, significant barriers exist for re-engaging in cultural burning. Indigenous communities in Canada have unique vulnerabilities to large and high-intensity wildfires as they are predominately located in remote, forested regions and lack financial support at federal and provincial levels to mitigate wildfire risk. Therefore, it is critical to uphold Indigenous expertise in leading effective and socially just fire stewardship. In this perspective, we demonstrate the benefits of cultural burning and identify five key barriers to advancing Indigenous fire stewardship in Canada. We also provide calls to action to assist with reducing preconceptions and misinformation and focus on creating space and respect for different knowledges and experiences. Despite growing concerns over wildfire risk and agency-stated intentions to establish Indigenous Peoples as partners in wildfire management, power imbalances still exist. The future and coexistence with fire in Canada needs to be a shared responsibility and led by Indigenous Peoples within their territories.

Putting fire on the map of Brazilian savanna ecoregions

The Brazilian savanna (Cerrado) is considered the most floristically diverse savanna in the world, home to more than seven thousand species. The region is a mosaic of savannas, grasslands and forests whose unique biophysical and landscape attributes are on the basis of a recent ecoregional map, paving the way to improved region-based strategies for land management actions. However, as a fire-prone ecosystem, Cerrado owes much of its distribution and ecological properties to the fire regime and contributes to an important parcel of South America burned area. Accordingly, any attempt to use ecoregion geography as a guide for management strategies should take fire into account, as an essential variable. The main aim of this study is to complement the ecoregional map of the Cerrado with information related to the fire component. Using remotely sensed information, we identify patterns and trends of fire frequency, intensity, seasonality, extent and scar size, and combine this information for each ecoregion, relying on a simple classification that summarizes the main fire characteristics over the last two decades. Results show a marked north-south fire activity gradient, with increased contributions from MATOPIBA, the latest agricultural frontier. Five ecoregions alone account for two thirds of yearly burned area. More intense fires are found in the Arc of Deforestation and eastern ecoregions, while ecoregions in MATOPIBA display decreasing fire intensity. An innovative analysis of fire scars stratified by size class shows that infrequent large fires are responsible for the majority of burned area. These large fires display positive trends over many ecoregions, whereas smaller fires, albeit more frequent, have been decreasing in number. The final fire classification scheme shows well defined spatially-aggregated groups, where trends are found to be the key factor to evaluate fire within their regional contexts. Results presented here provide new insights to improve fire management strategies under a changing climate.

Conservation of Earth's biodiversity is embedded in Indigenous fire stewardship

Large and severe wildfires are becoming increasingly common worldwide and are having extraordinary impacts on people and the species and ecosystems on which they depend. Indigenous peoples comprise only 5% of the world’s population but protect approximately 85% of the world’s biodiversity through stewardship of Indigenous-managed lands. Much of this is attributed to long-term and widespread relationships with and dependence on fire, which has been applied as a tool for managing landscapes for millennia. Fortunately, the revitalization of Indigenous fire stewardship is demonstrating the value of routinely applying controlled fire to adapt to changing environments while promoting desired landscapes, habitats, and species and supporting subsistence practices and livelihoods.

Increasingly, severe wildfires have led to declines in biodiversity across all of Earth’s vegetated biomes [D. B. McWethy et al., Nat. Sustain. 2, 797–804 (2019)]. Unfortunately, the displacement of Indigenous peoples and place-based societies that rely on and routinely practice fire stewardship has resulted in significant declines in biodiversity and the functional roles of people in shaping pyrodiverse systems [R. Bliege Bird et al., Proc. Natl. Acad. Sci. U.S.A. 117, 12904–12914 (2020)]. With the aim of assessing the impacts of Indigenous fire stewardship on biodiversity and species function across Earth’s major terrestrial biomes, we conducted a review of relevant primary data papers published from 1900 to present. We examined how the frequency, seasonality, and severity of human-ignited fires can improve or reduce reported metrics of biodiversity and habitat heterogeneity as well as changes to species composition across a range of taxa and spatial and temporal scales. A total of 79% of applicable studies reported increases in biodiversity as a result of fire stewardship, and 63% concluded that habitat heterogeneity was increased by the use of fire. All studies reported that fire stewardship occurred outside of the window of uncontrollable fire activity, and plants (woody and nonwoody vegetation) were the most intensively studied life forms. Three studies reported declines in biodiversity associated with increases in the use of high-severity fire as a result of the disruption of Indigenous-controlled fire regimes with the onset of colonization. Supporting Indigenous-led fire stewardship can assist with reviving important cultural practices while protecting human communities from increasingly severe wildfires, enhancing biodiversity, and increasing ecosystem heterogeneity.

Managing fires in a changing world: Fuel and weather determine fire behavior and safety in the neotropical savannas

Fire is an important ecological disturbance, but anthropogenic wildfires increasingly threaten native ecosystems and human lives. In fire-prone ecosystems, zero-fire policies have been replaced by active fire management to reduce the risk of wildfires and improve ecological outcomes. The environmental drivers of fire behavior are widely known, but climate change and deforestation are changing their roles, making fires less predictable. Thus, reassessing the main determinants of fire behavior is preeminent to allow for safe and adaptive uses of fire in protected areas (PA). We did this research in collaboration with PA managers during the initial implementation of a pilot Integrated Fire Management (IFM) program in the Brazilian savanna. The program mainly aimed to prevent large wildfires in the late-dry season and included prescribed burns during the rainy, early- and mid-dry seasons to create vegetation patch mosaics with different fire histories. We assessed fire behavior and its environmental drivers during prescribed fires in the mid-dry season (MF) and experimental late-dry season fires (LF) (emulating wildfires). We applied Linear Models to test for differences in fire intensity, heat released, combustion factor and flame height between fire seasons and to check the influence of meteorological and fuel conditions in these parameters. LF had a significantly higher fire intensity (3508 vs. 895 kW m^-1), heat released (5537 vs. 3329 kW m^-2), combustion factor (90 vs. 51%) and flame height (2.5 vs. 1.9 m) than MF. Relative humidity, air temperature, wind speed and fuel load were the best predictors of fire behavior, corroborating previous research. Air temperature and relative humidity pushed the seasonal differences in fire behavior while wind speed and fuel load showed similar effects across seasons. Our results emphasize the importance of considering primarily environmental variables during fire management planning, especially in the current climate changing world where extreme events and seasonal weather fluctuations are constantly defying our knowledge about fire behavior.

How fire interacts with habitat loss and fragmentation

Biodiversity faces many threats and these can interact to produce outcomes that may not be predicted by considering their effects in isolation. Habitat loss and fragmentation (hereafter 'fragmentation') and altered fire regimes are important threats to biodiversity, but their interactions have not been systematically evaluated across the globe. In this comprehensive synthesis, including 162 papers which provided 274 cases, we offer a framework for understanding how fire interacts with fragmentation. Fire and fragmentation interact in three main ways: (i) fire influences fragmentation (59% of 274 cases), where fire either destroys and fragments habitat or creates and connects habitat; (ii) fragmentation influences fire (25% of cases) where, after habitat is reduced in area and fragmented, fire in the landscape is subsequently altered because people suppress or ignite fires, or there is increased edge flammability or increased obstruction to fire spread; and (iii) where the two do not influence each other, but fire interacts with fragmentation to affect responses like species richness, abundance and extinction risk (16% of cases). Where fire and fragmentation do influence each other, feedback loops are possible that can lead to ecosystem conversion (e.g. forest to grassland). This is a well-documented threat in the tropics but with potential also to be important elsewhere. Fire interacts with fragmentation through scale-specific mechanisms: fire creates edges and drives edge effects; fire alters patch quality; and fire alters landscape-scale connectivity. We found only 12 cases in which studies reported the four essential strata for testing a full interaction, which were fragmented and unfragmented landscapes that both span contrasting fire histories, such as recently burnt and long unburnt vegetation. Simulation and empirical studies show that fire and fragmentation can interact synergistically, multiplicatively, antagonistically or additively. These cases highlight a key reason why understanding interactions is so important: when fire and fragmentation act together they can cause local extinctions, even when their separate effects are neutral. Whether fire-fragmentation interactions benefit or disadvantage species is often determined by the species' preferred successional stage. Adding fire to landscapes generally benefits early-successional plant and animal species, whereas it is detrimental to late-successional species. However, when fire interacts with fragmentation, the direction of effect of fire on a species could be reversed from the effect expected by successional preferences. Adding fire to fragmented landscapes can be detrimental for species that would normally co-exist with fire, because species may no longer be able to disperse to their preferred successional stage. Further, animals may be attracted to particular successional stages leading to unexpected responses to fragmentation, such as higher abundance in more isolated unburnt patches. Growing human populations and increasing resource consumption suggest that fragmentation trends will worsen over coming years. Combined with increasing alteration of fire regimes due to climate change and human-caused ignitions, interactions of fire with fragmentation are likely to become more common. Our new framework paves the way for developing a better understanding of how fire interacts with fragmentation, and for conserving biodiversity in the face of these emerging challenges.

How changing fire management policies affect fire seasonality and livelihoods

There is a long history of fire management in African savannas, but knowledge of historical and current use of fire is scarce in savanna-woodland biomes. This study explores past and present fire management practices and perceptions of the Khwe (former hunter-gatherers) and Mbukushu (agropastoralists) communities as well as government and non-government stakeholders in Bwabwata National Park in north-east Namibia. Semi-structured interviews and focus groups were used in combination with satellite data (from 2000 to 2015), to investigate historical and current fire management dynamics. Results show that political dynamics in the region disrupted traditional fire practices, specifically a policy of fire suppression was initiated by colonial governments in 1888 and maintained during independence until 2005. Both the Khwe and Mbukushu communities use early season (i.e. between April and July) fires for diverse interrelated historical and current livelihood activities, and park management for managing late season fires. The Mbukushu community also use late season burns to prepare land for crops. In this study, we use a pyrogeographic framework to understand the human dimension of fires. This study reveals how today's fire management practices and policies, specifically the resurgence of early season burning are entrenched in the past. Understanding and acknowledging the social and cultural dynamics of fire, alongside participatory stakeholder engagement is critical for managing fires in the future.

The Role of Vegetation on the Dynamics of Water and Fire in the Cerrado Ecosystems: Implications for Management and Conservation

The Cerrado is the richest savanna and is undergoing one of the planet’s most rapid land transformations for pasture and agriculture; around 45% of the biome has been deforested. Agriculture is of strategic importance to Brazil, but it also modifies ecosystems and jeopardizes habitats and biodiversity. Well-managed agricultural lands can have a favorable impact on environmental conservation. In this paper, we reviewed our current knowledge about water ecology and fire management to show that an ecosystem services perspective can bring about a conciliation of agriculture production with conservation by supporting effective land use decision-making and the optimization of public policy. The landscape/watershed scale seems to be the most relevant for decision-making on how to achieve production and conservation results. This scale appears to be an appropriate level for engaging with stakeholders. Fire frequency and timing (season) combination are determinant of individuals’ survivorship. The combination determines vegetation recovery, and it is important to maintain high biodiversity, especially for the herbaceous layer, but it is a limitation to woody vegetation recovery. A pragmatic and conciliatory land use agenda must be based on scientific knowledge and support innovative decision-making solutions for policy-makers and stakeholders, particularly farmers and donors.

Preventing traditional management can cause grassland loss within 30 years in southern Brazil

Woody encroachment threatens several ecosystems around the world. In general, management of grasslands includes regulation of fire and grazing regimes. Changes in these two types of disturbances are potential drivers of woody encroachment. Here we assessed how the traditional management carried out by local landholders affects a highland grassland ecosystem in southern Brazil. We hypothesized that grasslands converted to protected areas undergo fast woody encroachment. To reconstruct changes in vegetation, we interviewed former and current landholders and coupled their knowledge with an analysis of aerial and satellite images. During the first 11 years without fire and cattle, woody encroachment in grasslands increased exponentially. Woody encroachment occurred mostly by the replacement of grasslands by shrublands. Meanwhile, grasslands under traditional management remained almost unchanged for the last 40 years. The management of fire by local landholders has been part of their traditional practices for decades. Such management prevents large-scale wildfires and maintains natural highland grasslands. The quick pace of shrub encroachment in such grasslands threatens its exclusive diversity, human well-being and regional cultural heritage. Thus, conservation policies are needed to regulate and instruct about the use of fire as a management tool in highland grasslands of southern Brazil.

Seasonal fire management by traditional cattle ranchers prevents the spread of wildfire in the Brazilian Cerrado

The use of fire by cattle ranchers is a major source of conflict between conservationists and local communities in tropical savannas. We evaluate the role of traditional pastoral management in wildfire prevention in two protected areas within the Brazilian savanna. Fine-grain field data from transect walks and interviews were combined with geospatial data at landscape scale to compare fire regimes in community-managed areas with those in government-managed areas. Local pastoral management creates seasonal mosaic patterns of burnings performed for productive activities and for deliberate landscape management, i.e. to protect fire-sensitive vegetation and avoid wildfires. Whereas government-managed areas were affected by large biennial late dry season wildfires, community-managed areas with a regular fire regime suffered less damage. These systems are under threat and poorly understood by researchers and environmental managers. In order to improve fire management in tropical savannas, greater understanding of pastoral management practices and their spatiotemporal dimensions is required.