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1. Indigenous peoples have been managing fire‐prone landscapes for millennia, especially in tropical savannas, thereby maintaining carbon stocks and pyrodiversity and ensuring food security. In some indigenous lands in Brazil, fire brigades are composed of indigenous people, integrating their traditional knowledge in Brazilian fire management policies; however, the effectiveness of their management is largely undocumented. Nevertheless, we need to know the effectiveness of indigenous fire brigades and their influence on fire patterns. 2. Here, we evaluate an 18‐year historical series of fire patterns and burn scars, comparing periods with and without indigenous brigade activity, to describe the role of indigenous fire brigades in the Kadiwéu Indigenous Territory. In this Indigenous Territory, fire brigades composed of indigenous people have been instituted, trained and maintained by the National Center of Prevention and Combat of Wildfire (PREVFOGO/IBAMA) since 2009. These brigades are responsible for fire management throughout the Kadiwéu Indigenous Territory using controlled burning, prescribed burning, and combating wildfires. 3. We found that fire management by the indigenous brigades has reduced fire frequency by 80% in the areas with high fire frequency (over 70% of the analyzed time). Management also reduced the size of the area burned by 53% and the influence of climate over the total area burned. According to our models, the area affected by fires is mainly influenced by annual rainfall in the absence of indigenous brigades; in contrast, climatic factors could not explain the variation in the burned area in the period without indigenous brigades. 4. Synthesis and applications — The fire management realized by the indigenous brigades can modify the fire regime. These changes in the fire regime can include: changes in spatial patterns, the magnitude of fires, and reduction in the influence of climate on fire regimes. Hence, the management carried out by the indigenous brigades can be considered an important tool for fire management. In addition, demonstrates the importance of programs that integrate traditional indigenous knowledge with fire management policies, such as the Integrated Fire Management (IFM), to construct effective management strategies.
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Indigenous peoples have been using fire in the cerrado (savannas) of Brazil as a form of management for thousands of years, yet we have little information on why, when and how these fire practices take place. The aim of this paper was to explore the traditional use of fire as a management tool by the Krah indigenous group living in the north-eastern region of Tocantns state, Brazil. The results indicate that the Krah burn for a variety of reasons throughout the dry season, thereby producing a mosaic of burned and unburned patches in the landscape. The paper discusses this burning regime in the context of contemporary issues regarding fire management, and in the face of changing perceptions to fire by the Krah themselves.
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Flood and fire act as ecological filters which can interact to shape forest structure and species composition. Our objective was to investigate how the interaction between fire and flood influences richness, abundance, basal area and species composition of the tree community and the monodominant belts of Attalea phalerata Mart. in forest islets of the Pantanal wetland. We used satellite images to find 12 forest islets without fire events from 1998 to 2014, and 12 forest islets burned only once in the same period in a fire event in 2009. In these forest islets, we set up a transect with 10 to 14 contiguous 5 × 10 m plots and sampled all trees with a diameter at breast height of ≥ 4.7 cm. We also measured the watermark height. Flooding influenced species richness and abundance, increased toward wetter areas of the forest islet flood gradient. In contrast, the interaction between fire and flood inverted that trend, with richness and abundance increasing in flood-free areas. Total basal area increases in the more flooded areas of the gradient. The fire or the interaction between fire and flooding did not influence the basal area. The abundance of A. phalerata increased with flood level and under the fire-flood interaction. We conclude that the interaction between fire and flood influences forest islet structure and species composition; moreover, it favors A. phalerata monodominance.
Article
URL providing 50 days' free access: https://authors.elsevier.com/a/1d8aq14Z6thO2i In the Brazilian Pantanal, wildfire occurrence has increased, reaching record highs of over 40,000 km² in 2020. Smoke from wildfires worsened the situation of isolated, as well as urban communities, already under an increasing toll of COVID-19. Here we review the impacts and the possible causes of the 2020 mega-fires and recommend improvements for public policies and fire management in this wetland. We calculated the amount of area burnt annually since 2003 and describe patterns in precipitation and water level measurements of the Paraguay River. Our analyses revealed that the 2020 wildfires were historically unprecedented, as 43% of the area (over 17,200 km²) had not been burnt previously in the last two decades. The extent of area affected in 2020 represents a 376% increase compared to the annual average of the area burnt annually in the last two decades, double than the value in 2019. Potential factors responsible for this increase are (i) severe drought decreased water levels, (ii) the fire corridor was located in the Paraguay River flood zone, (iii) constraints on firefighters, (iv) insufficient fire prevention strategy and agency budget reductions, and (v) recent landscape changes. Climate and land use change will further increase the frequency of these extreme events. To make fire management more efficient and cost-effective, we recommend the implementation of an Integrated Fire Management program in the Pantanal. Stakeholders should use existing traditional, local ecological, and scientific knowledge to form a collective strategy with clear, achievable, measurable goals, considering the socio-ecological context. Permanent fire brigades, including indigenous members, should conduct year-round fire management. Communities should cooperate to create a collaborative network for wildfire prevention, the location and characteristics (including flammability) of infrastructures should be (re)planned in fire-prone environments considering and managing fire-catalysed transitions, and depending on the severity of wildfires. The 2020 wildfires were tackled in an ad-hoc fashion and prioritisation of areas for urgent financial investment, management, protection, and restoration is necessary to prevent this catastrophe from happening again.
Article
Optimal sexual reproduction in relation to fire effects varies in Fabaceae species. Calliandra species have a large investment in reproduction. We investigated the consequences of fire during the fruiting period of Calliandra parviflora Benth., by checking fruit exposure to fire, pre‐dispersal seed predator infestation, and the effect of fruit burning on germination. We conducted this study in a floodable savanna in central Brazil, where we collected burnt and unburnt fruits. We measured the fruit and seed mass, and counted the number of damaged and undamaged seeds and live larvae per fruit. We analyzed the seed germination percentage from burnt and unburnt fruits. The burnt fruits presented greater mass than the unburnt fruits, despite their seed mass being similar. The number of damaged seeds per fruit was only slightly higher in burnt compared to unburnt fruits (p = 0.047). The number of larvae on pre‐dispersal seeds per fruit varied from 0 to 4 and did not differ between burnt and unburnt fruits. The germination percentage of unburnt fruit seeds (mean = 22 ± 17%), was significantly higher than that of burnt fruit (mean = 3.0 ± 2.0%, p < 0.001). Fire during fruiting or pre‐dispersion decreases seed germination from 22 to 3%, but it does not hurt vegetative regeneration or resprout capacity of C. parviflora, which is a facultative seeder. Hence, we suggest that C. parviflora has potential for post‐fire restoration in floodable open grassy savannas, in the ecotone between Cerrado and Pantanal, because this species may sprout quickly after first post‐fire rains. Fire during fruiting or pre‐dispersion decreases seed germination from 22 to 3%, but it does not hurt vegetative regeneration or resprout capacity of Calliandra parviflora, which is a facultative seeder. In addition to fire, the sexual C. parviflora reproduction is under another ecological filter, infestation by seed predators larvae. These ecological filters helps to decrease dissemination of C. parviflora, considering its apparent degree of rusticity. These traits enable its potential for post‐fire restoration in floodable open grassy savannas, in the ecotone between Cerrado and Pantanal, where C. parviflora may sprout quickly after first post‐fire rains.
Article
Wildfires have important effects on wildlife habitat. Within fire perimeters, 'fire refugia' are unburned or less severely burned areas that contain residual pre-fire habitat structures and facilitate species persistence following fire. However, fire refugia may vary in their relative quality. The ability to evaluate the relative quality of fire refugia for wildlife habitat may help efficiently allocate resources for post-fire conservation planning, especially for at-risk species. Using spatial overlays of habitat models and burn severity data, we developed the refugia index, a flexible multi-scale, multi-criteria fuzzy logic model to assess the value of unburned areas for wildlife habitat affected by wildfires and other disturbances. We conducted a case study of the northern spotted owl (Strix occidentalis caurina) and applied our method to 4278 unburned areas in 15 fires that each burned > 400 ha of spotted owl nesting/roosting habitat in the eastern Cascade Mountains, U.S.A. In our study area, unburned areas represented ~ 1.7% of the area within the fire perimeters. Most fire refugia were low quality, because unburned areas were small relative to the desired nest patch size of spotted owls and contained little suitable nesting/ roosting habitat. However, each fire contained a few high-quality fire refugia, because they co-occurred with suitable nesting/roosting habitat and were surrounded by desirable habitat characteristics for spotted owls. Our method illustrates how land managers can use readily available spatial data and analysis tools to understand fire effects on species' habitat (e.g., habitat lost) and prioritize areas for post-fire conservation and management.
Article
Environmental filters affect species diversity. Understanding their influence on plant communities is one of the main challenges of ecology in the search for solutions to the management and conservation of floodable savannas. To shed more light on this challenge, the present work asked if the interactions between flood and fire influence the richness of community and favor the abundance and basal area of the monodominant Pantanal species Tabebuia aurea. We also asked what role earth-mounds play in this process. To address these questions, we used Landsat-5 and -8 and Resourcesat-1 satellite data; to access the fire history in monodominant stands of T. aurea in the Pantanal from 2003 to 2017. We chose 37 areas with 2 to 9 annual fire episodes. A total of 125 25 × 25 m plots were established in the different areas, to sample arboreal strata. We sampled all individuals ≥3.18 cm in diameter at breast height (dbh). In each plot, we measured height by the watermark from the last flooding on each individual as a proxy of inundation level. We applied generalized linear model (GLM) analyses to compare effects of flood and fire on abundance, richness and basal area, on and off earth-mounds using negative binomial, Poisson and Gaussian distribution, respectively. We sampled 2411 individuals distributed among 19 families, 31 genera and 36 species. Under higher fire frequency, abundance, richness and basal area of all species decreased with increase of water level. However, the abundance and basal area of Tabebuia aurea remained higher than those of other species. Under lower fire frequency, the abundance and richness of all species in the community increased with water level. Basal area, however, decreased with increasing water level, such that individuals with larger basal area were found under lower fire frequency. Under high fire frequency earth-mounds protected T. aurea individuals from fire and flood. Earth-mounds influenced species richness and basal area only under medium-low fire frequency. Results show that monodominance of T. aurea benefits from the interaction between fire and flood, with some help from earth-mounds. Individuals of other tree species, show tolerance to high flood levels or high fire frequencies, but not the interaction between fire and flood. This dynamic strengthens the monodominance of T. aurea, as the number of individuals also increases. Our results show that flood and fire are important to the conservation of this monodominant community.
Article
1. Disentangling species strategies that confer resilience to natural disturbances is key to conserving and restoring savanna ecosystems. Fire is a recurrent disturbance in savannas, and savanna vegetation is highly adapted to and often dependent on fire. However, although the woody component of tropical savannas is well studied, we still do not understand how ground‐layer plant communities respond to fire, limiting conservation and management actions. 2. We investigated the effects of prescribed fire on community structure and composition, and evaluated which traits are involved in plant community regeneration after fire in the cerrado ground layer. We assessed traits related to species persistence and colonization capacity after fire, including resprouter type, underground structure, fire‐induced flowering, regeneration strategy and growth form. We searched for functional groups related to response to fire, to shed light on the main strategies of post‐fire recovery among species in the ground layer. 3. Fire changed ground‐layer community structure and composition in the short term, leading to greater plant species richness, population densities, and increasing bare soil, compared with unburned communities. Eight months after fire, species abundance did not differ from pre‐disturbance values for 86% of the species, demonstrating the resilience of this layer to fire. Only one ruderal species was disadvantaged by fire and 13% of the species benefited. Rapid recovery of soil cover by native vegetation in burned areas was driven by species with high capacity to resprout and spread vegetatively. Recovery of the savanna ground‐layer community, as a whole, resulted from a combination of different species traits. We summarized these traits into five large groups, encompassing key strategies involved in ground layer regeneration after fire. Synthesis: Fire dramatically changes the ground layer of savanna vegetation in the short term, but the system is highly resilient, quickly recovering the pre‐fire state. Recovery involves different strategies, which we categorized into five functional groups of plant species: grasses, seeders, bloomers, undergrounders, and resprouters. Knowledge of these diverse strategies should be used as a tool to assess conservation and restoration status of fire‐resilient ecosystems in the cerrado.
Article
The Indigenous Lands in Brazil today resemble a steam locomotive, where the government and the indigenous add wood to the boiler and the conservationists push the brakes. Arranged on the rails and along the way of this locomotive are more than 100 million hectares of the largest tropical forest on the planet. In this article we evaluate the advance of soybean cultivation and fire foci in indigenous lands using remote sensing and discuss the possible effects of a liberation of the economic exploitation in these territories intended by the Brazilian government and requested by the indigenous people themselves. We present that even with the prohibition of economic exploitation on indigenous lands, there are large concentrations of fires in those territories which undermine public policies in Brazil, both in maintaining biodiversity as the assumed climate agreements. Indigenous Lands (ILs) in Brazil are strategic for maintaining biodiversity and providing ecosystem services, such as carbon storage and hydrological cycle. ILs comprise of 721 areas and occupy 13.8% of the Brazilian territory (1,174,263 km 2). Most of them are in the Legal Amazon, with 115.3 million hectares (Mha) distributed in 424 areas representing 23% of the Amazonian territory and 98.
Article
Defining the reference system for restoration projects in regions characterized by complex vegetation mosaics is challenging. Misidentification of anthropogenically‐degraded grasslands or savannas as natural vegetation can lead to inappropriate restoration efforts and legislation. Here we use the Cerrado region of Brazil as an example of the importance of clearly defining multiple natural and anthropogenically‐altered states in grassland‐savanna‐forest mosaics to set appropriate restoration targets and select cost‐effective restoration methods. We contend that the differences in Cerrado vegetation composition originally were driven by soil conditions and secondarily by fire frequency and precipitation patterns that differ across the region. Grasslands are found on the shallowest, least fertile soils and/or in waterlogged soils; scleromorphic forest (cerradão) are generally found on deeper, more fertile soils; and savannas occupy an intermediate position. This biophysical template has been overlain by a range of human land use intensities that strongly affect resilience. We define three main, natural vegetation types – grassland, savanna, and scleromorphic forest ‐ to (1) distinguish between original and degraded states and (2) set appropriate targets for and guide restoration. For example, areas that were originally scleromorphic forest are likely to regenerate naturally following low or medium intensity land use due extensive resprouting of woody plants, whereas grassland restoration requires reintroduction of grass and forb species that do not tolerate soil disturbance and exotic grass competition. Planting trees into historic grasslands results in inappropriate restoration targets and often restoration failure. Correctly identifying original vegetation types is critical to most effectively allocate scarce restoration funding. This article is protected by copyright. All rights reserved.
Article
The natural regeneration management is a good strategy of ecological restoration of the Atlantic Forest, one of the most devastated biomes on the planet. However, the frequent occurrence of wildfires is one of the challenges to the success of this method. The objective of this study was to evaluate the effects of wildfires on forest dynamics in Atlantic Forest. The studied area was explored during the coffee cycle when plantations replaced primary forests. We used remote sensing data to analyze the forest dynamics over a period of 50 years (1966–2016). We used the INPE burn database to find the occurrence of hot spots from 1998 to 2016. During this period, we selected the years most affected by the fires for the identification of fire scars using the Normalized Burn Ratio spectral index. From this set of information, we used the methodology of weights of evidence to relate forest dynamics and wildfire events with biophysical and anthropic variables. The results showed that in 1966 the forest area accounted for 8.01% of the land cover, and in 2016 this number rose to 18.55% due to the spontaneous natural regeneration process. The regenerating areas were mainly related to the proximity of the remaining fragments and the portions of the landscape receiving the least amount of global solar radiation. The proximity to urban areas, roads and highways, damaged regeneration and favored both deforestation and wildfire events. Fire scars preferentially occur where there is greater sun exposure. It is possible to observe a negative correlation between the natural regeneration process and the fire scars. We concluded that fire severity is one of the factors that shape the landscape of the region while slowing the regeneration process in preferential areas.
Book
This book introduces the key stages of niche-based habitat suitability model building, evaluation and prediction required for understanding and predicting future patterns of species and biodiversity. Beginning with the main theory behind ecological niches and species distributions, the book proceeds through all major steps of model building, from conceptualization and model training to model evaluation and spatio-temporal predictions. Extensive examples using R support graduate students and researchers in quantifying ecological niches and predicting species distributions with their own data, and help to address key environmental and conservation problems. Reflecting this highly active field of research, the book incorporates the latest developments from informatics and statistics, as well as using data from remote sources such as satellite imagery. A website at www.unil.ch/hsdm contains the codes and supporting material required to run the examples and teach courses. With applications in evolutionary biology, biogeography and conservation biology, the book emphasizes how these models can be used to make predictions in global and regional biodiversity assessments Written by highly experienced researchers in this active field, the book represents a contribution to strengthen modeling standards in basic and applied habitat suitability model research The most recent developments in informatics, statistics and data manipulation in R are incorporated. © Antoine Guisan, Wilfried Thuiller, and Niklaus E. Zimmermann 2017. All rights reserved.
Article
Fire profoundly influences people, climate, and ecosystems ( 1 ). The impacts of this interaction are likely to grow, with climate models forecasting widespread increases in fire frequency and intensity because of rising global temperatures ( 2 ). However, the relationship between fire and biodiversity is complex ( 3 , 4 ). Many plants and animals require fire for their survival, yet even in fire-prone ecosystems, some species and communities are highly sensitive to fire. Recent studies ( 2 , 3 , 5 , 6 ) are helping to define fire regimes that support the conservation of species with different requirements in a rapidly changing world.
Article
Woody encroachment is a pervasive challenge facing savanna and grassland managers worldwide. Proposed drivers of the phenomenon range from local changes in fire, herbivory, and direct human impacts, to global changes in climate or atmospheric [CO2] that may be accelerating woody growth. The relative influences of local vs. global drivers and their interactions are largely unknown, but will determine the extent to which management can limit woody encroachment locally. We examined recent woody encroachment in Hluhluwe-iMfolozi Park in South Africa from 2007–2014. Vegetation transects were distributed across broad gradients in rainfall, herbivore use intensity and fire frequency, on a variety of soils. Density of medium trees (2–4 m tall) increased dramatically (by 46%) in seven years, while densities of small and large trees remained constant. Increases in medium tree density were largest on sandy soils, where fires were infrequent, and where grazing pressure increased. Tree density increased even where recent fire frequency was similar to historical fire regimes. These potentially widespread increases, unexplained by changes in local disturbance history, suggest the possible influence of drivers outside the scope of local control. Synthesis and applications. Fire can provide a limited buffer against generalized woody encroachment in savannas, but may only prevent further encroachment where managers can increase fire frequency. Grazing, which can limit fire frequency and intensity, may come increasingly into conflict with efforts to control woody encroachment, presenting a stark choice for savanna managers between maintenance of short-term grazer population productivity and longer-term prevention of woody encroachment. This article is protected by copyright. All rights reserved.
Article
Fire has a major impact on the structure and function of many ecosystems globally. Pyrodiversity, the diversity of fires within a region (where diversity is based on fire characteristics such as extent, severity, and frequency), has been hypothesized to promote biodiversity, but changing climate and land management practices have eroded pyrodiversity. To assess whether changes in pyrodiversity will have impacts on ecological communities, we must first understand the mechanisms that might enable pyrodiversity to sustain biodiversity, and how such changes might interact with other disturbances such as drought. Focusing on plant-pollinator communities in mixed-conifer forest with frequent fire in Yosemite National Park, California, we examine how pyrodiversity, combined with drought intensity, influences those communities. We find that pyrodiversity is positively related to the richness of the pollinators, flowering plants, and plant-pollinator interactions. On average, a 5% increase in pyrodiversity led to the gain of approximately one pollinator and one flowering plant species and nearly two interactions. We also find that a diversity of fire characteristics contributes to the spatial heterogeneity (β-diversity) of plant and pollinator communities. Lastly, we find evidence that fire diversity buffers pollinator communities against the effects of drought-induced floral resource scarcity. Fire diversity is thus important for the maintenance of flowering plant and pollinator diversity and predicted shifts in fire regimes to include less pyrodiversity compounded with increasing drought occurrence will negatively influence the richness of these communities in this and other forested ecosystems. In addition, lower heterogeneity of fire severity may act to reduce spatial turnover of plant-pollinator communities. The heterogeneity of community composition is a primary determinant of the total species diversity present in a landscape, and thus, lower pyrodiversity may negatively affect the richness of plant-pollinator communities across large spatial scales.
Article
The Cerrado (Brazilian savanna) is a biodiversity hotspot with a history of fire that goes back as far as 10 million years. Fire has influenced the evolution of several aspects of the vegetation, including reproduction and life cycles. This study tested how fire by-products such as heat and smoke affect the germination of six species common to two Cerrado open physiognomies: wet grasslands and the campo sujo (grassland with scattered shrubs and dwarf trees). We subjected seeds collected in northern Brazil to heat shock and smoke treatments, both separately and combined, using different temperatures, exposure times, and smoke concentrations in aqueous solutions. High temperatures and smoke did not break seed dormancy nor stimulate germination of the Cerrado study species. However, seeds were not killed by high temperatures, indicating that they are fire-tolerant. Our findings differed from those of other fire-prone ecosystems (mostly of Mediterranean vegetation), where fire stimulates germination. Moreover, we provide important information regarding germination strategies of non-woody Cerrado plants, showing the importance of considering the tolerance of seeds to high temperatures when evaluating fire-related traits in fire-prone ecosystems. Abstract in Portuguese is available with online material.
Article
The Cerrado is a fire-dependent savanna requiring a clear and urgent fire management policy. The extensive misuse of fire for deforestation or pasture management in Brazil has created an overall perception that its use is always deleterious. This view, reinforced by threats of global warming and climatic change, has lead to current policies of fire suppression. Cerrado ecosystems depend on the historical fire regime to maintain their structure, biodiversity and functioning. The suppression of fire has transformed savanna vegetation into forests, causing biodiversity losses and drastic changes in ecological processes. Policy implications. The National Fire Policy required by law must be urgently implemented in Brazil, including use of fire for Cerrado conservation in public and private lands on the basis of existing knowledge of indigenous people and scientists. Objective regulations on prescribed burning, land manager training, incentives for fire research and experimentation and a broad campaign to disseminate the benefits of fire for Cerrado conservation should be the cornerstones of the policy. If implemented, the policy can give the biodiversity of the Cerrado a future that has previously been severely threatened by fire suppression.
Article
Models based on species distributions are widely used and serve important purposes in ecology, biogeography and conservation. Their continuous predictions of environmental suitability are commonly converted into a binary classification of predicted (or potential) presences and absences, whose accuracy is then evaluated through a number of measures that have been the subject of recent reviews. We propose four additional measures that analyse observation-prediction mismatch from a different angle – namely, from the perspective of the predicted rather than the observed area – and add to the existing toolset of model evaluation methods. We explain how these measures can complete the view provided by the existing measures, allowing further insights into distribution model predictions. We also describe how they can be particularly useful when using models to forecast the spread of diseases or of invasive species and to predict modifications in species’ distributions under climate and land-use change.
Article
Gradient analysis is a powerful technique to analyse for, and detect change in, the dynamics, structure, and function of ecosystems. This review outlines the properties of gradients in space and time and uses an example of forests in the Rocky Mountain Physiographic Province to demonstrate constraints, the complex mosaics associated with distributional limits, transfer across boundaries, the role of disturbance, and threshold dynamics. A climate-change scenario is developed to hypothesize future changes in boundary movements, community mosaics, and ecosystem properties along elevational and latitudinal gradients in the Rocky Mountain Province. Mechanistic explanations of ecological phenomena that are necessary for management require information on: the physical environmental constraints operating on the ecosystem; the biota that operate within those constraints; and the interactions among the biota and between the biota and environment. Modeling that includes such spatial gradients provides the foundation for local to regional management programs. -from Author
Article
AimWe explored the relationships among rainfall, fire and tree population dynamics during the twentieth century. Relationships were analysed on seasonal, interannual and multiannual time scales.LocationThe study was conducted at ecotones between Andean grasslands and montane forests in north-western Argentina. In this area of subtropical monsoonal climate (wet summers, dry winters), annual rainfall has increased and forests have expanded into grasslands and shrublands during the 20th century.Methods We used annual tree-rings of alder (Alnus acuminata H. B. K.), the dominant tree species, to date fire scars on 265 trees and determine establishment dates of 455 trees dispersed over areas > 100 ha at five sites. We also sampled tree establishment and resprouting in 21 plots of 0.1–5 ha and determined mortality patterns in one recently burnt stand.ResultsFire occurrence during the winter dry season tends to lag by 1 year after years of above-average moisture availability. This pattern is probably due to enhanced production of fine fuels during the growing season of the preceding years. Over 5-year periods, higher fire frequency is associated with greater variability in rainfall. On a 5-year time scale, tree establishment is also associated with higher rainfall variability. Tree age structures suggest that a decades-long trend towards increased rainfall may also promote forest expansion. By the age of 10–20 years, Alnus acuminata attains a large enough size to survive the low-intensity fires typical of these open woodland sites. Recovery of A. acuminata after fire is also assured by vigorous resprouting and seedling establishment after fire removes or reduces the herbaceous understorey. During relatively wet periods or at relatively wet sites, fire appears to favour forest expansion by reducing competition between tree juveniles and non-forest vegetation.Main conclusionsThese results demonstrate the importance of variability in interannual rainfall as an influence on the dynamics that control ecotones between high Andean grasslands and subtropical montane forest.