Article

Prioritising areas for wildfire prevention and post-fire restoration in the Brazilian Pantanal

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Abstract

In 2020, fires in the Pantanal, the world's largest continuous tropical wetland, made global news. The flames destroyed almost one-third of the biome. Furthermore, 43% of the affected area was burnt for the first time in 20 or even more years. As the combination of extreme drought and anthropogenic actions that caused these extreme wildfires is still prevalent, scientifically informed actions are necessary to prevent catastrophic fires in the future. Fire prevention, as well as restoration need to be spatially prioritised, as it is unfeasible to plan actions for the whole extent (150,355 km2) of the Brazilian Pantanal. In this study, we identified areas of high fire risk based on meteorological fire risk tendency for 1980–2020, fire intensity, last year with fire, the recurrence of fires for 2003–2020, and remaining areas of natural forest vegetation around watercourses. These native remnants include unburnt areas that can serve as refuges for fire-sensitive species and are important for fire prevention. We identified 246 km2 with high fire risk, i.e., high probability of megafires, with vegetation types that support fire-sensitive plant species. We found that while 179 km2 had high or medium natural regeneration potential, 66 km2 had low potential and needed active restoration. Over 3120 km2 have been severely degraded by recent fires. About 93% of these areas have high or medium potential for natural regeneration, where the suggested actions are passive restoration and Integrated Fire Management. We estimated the cost of post-fire restoration for areas with high and medium potential for natural regeneration to be around 123 million USD. In areas with low regeneration potential (219 km2), we suggest active restoration. The cost to restore these areas using transplanted seedlings or enrichment planting is estimated between 28 and 151 million USD.

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Wildfires have played a determining role in distribution, composition and structure of many ecosystems worldwide and climatic changes are widely considered to be a major driver of future fire regime changes. However, forecasting future climatic change induced impacts on fire regimes will require a clearer understanding of other drivers of abrupt fire regime changes. Here, we focus on evidence from different environmental and temporal settings of fire regimes changes that are not directly attributed to climatic changes. We review key cases of these abrupt fire regime changes at different spatial and temporal scales, including those directly driven (i) by fauna, (ii) by invasive plant species, and (iii) by socio-economic and policy changes. All these drivers might generate non-linear effects of landscape changes in fuel structure; that is, they generate fuel changes that can cross thresholds of landscape continuity, and thus drastically change fire activity. Although climatic changes might contribute to some of these changes, there are also many instances that are not primarily linked to climatic shifts. Understanding the mechanism driving fire regime changes should contribute to our ability to better assess future fire regimes.
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Flood and fire are considered ecological filters and can shape the structure of plant communities in tropical wetlands and floodable savannas, especially on regeneration. However, in systems exposed to recurrent flood and fire, there is little information on the vegetation effects and implications for management. To test the effects of fire on flood-prone riparian forests of the Brazilian Pantanal, we analyzed how natural flood and fire can interact and influence species composition, abundance, and richness of the woody regeneration. This neotropical savanna wetland is subjected to annual and predictable flood pulses and to occasional wildfires. We established 106 plots (2 � 5 m) within the riparian forest of the Paraguay River in burned (recurrent) and unburned areas from 2001 to 2011 (verified on satellite images). We compared the plot topography with historic data of river levels from Ladário gauge in the same period. We sampled all trees, shrubs, and lianas from 0.3 to 2.5 m high. Flood in plots varied from 38 (higher areas) to 98 (lower areas) days year�1. Our results show that variation in flood duration and occurrence of fire interact in a synergistic manner to reduce stem numbers on regeneration and modify species composition and distribution. Species richness differed in relation to flood duration, but not to fire. All growth forms had low number of exclusive species in both unburned and burned sites. Our results have implications for wetland management. The natural flooding regime is responsible for the diversity of habitats and species. Changes of the hydrology due to land management or climatic changes may result in changes of fire regime with consequences for the analyzed vegetation patterns and ecosystem functions. This neotropical savanna wetland system is stable and resilient as long as its natural patterns and periodicities of flooding and wildfires are maintained. Our results point to the necessity to analyze the interacting effects of selective environmental forces in order to be able to preserve the form and functions of the huge wetlands of the Pantanal.
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Ecological rehabilitation is subject to a variety of risks affecting the likely return on investment. We propose an options approach to allocating scarce conservation funds that explicitly allows for the irreversibility of investment and risks to investment payoffs. The approach captures ecosystem dynamics from extinction debt, as well as ecological and climatic risks at the project scale. Climatic risks are introduced through three channels: the effects of climate change on species loss, future rehabilitation benefits and frequency of catastrophic events. Our results suggest that allocating voluntary rehabilitation contracts on the basis of real options criteria increases cost-efficiency and delivers greater value for money for the Government when compared with the conventional cost-effectiveness criterion as it is illustrated for the case of Box Gum Grassy Woodland rehabilitation in Australia.
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AimBiodiversity information is the focus of major initiatives aimed at assembling large-scale primary-data documentation (‘digital accessible knowledge’) of the distribution of life on Earth. Recent efforts within Brazil have assembled a massive amount of such documentation for Brazilian plants, which we analyse in this study. Our aim is to identify areas representing gaps in current knowledge; these gaps can guide future botanical exploration and discovery in Brazil. LocationBrazil. Methods We assessed angiosperm inventories across Brazil at diverse spatial scales using statistics that summarize inventory completeness. In particular, we assess the completeness of geographical knowledge of Brazilian floras as measured in terms of geographical distance and climatic difference from well-documented sites. ResultsSpatial knowledge of Brazilian angiosperms is very unevenly distributed: well-known sites are concentrated in eastern and southern regions, whereas the remainder of the country remains poorly documented. Worse still, in many regions, areas lacking detailed botanical documentation coincide with areas of intense habitat destruction, such that many such sites will never be documented scientifically. Main conclusionsThis study illustrates how biodiversity survey and inventory efforts can be guided by existing knowledge. That is, to the extent that existing biodiversity knowledge is made digital and openly available, and to the extent that information is sufficiently comprehensive and informative, spatial summaries of completeness such as that presented here offer clear and strategic directions for maximizing the yield of new knowledge from any de novo field efforts.
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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.
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This Communication reports on the fires recently seen in the Pantanal region, in Brazil, the largely continental wetland globally. It outlines the causes of the problem and some of the means which may be deployed to address them.
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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.
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Litterfall is an indicator of ecosystem function and its temporal dynamics can be used to evaluate self-organizing ecosystems on a recovery trajectory following restoration. Few studies have evaluated the recovery trajectories of forest litterfall by simultaneously monitoring forest restoration strategies and reference ecosystems. The general objective of our study was to determine the functional recovery of an abandoned pasture under passive and active restoration, and in secondary (40-year-old) and mature (120-year-old) forest, by analyzing litterfall and its components (leaves, flowers, fruits, woody parts) over a period of five consecutive years. We determined the vegetation structure and tree species composition of these four conditions and compared 1) production of litterfall, leaves, flowers and fruits, 2) leaf litter nutrient inputs (C and N) and, 3) recovery by tree species in leaf litterfall. In five years, litterfall increased from 2.6 to 7.8 Mg ha⁻¹ and from 3.5 to 9.1 Mg ha⁻¹ in the passive and active restoration treatments, respectively, while it increased from 6.0 to 8.6 Mg ha⁻¹ in the secondary forest. In the mature forest, litterfall varied around 10.0 Mg ha⁻¹. The reproductive component increased significantly in restoration (0.3 to 1.5 Mg ha⁻¹) but remained around 0.6 Mg ha⁻¹ in secondary and 1.3 Mg ha⁻¹ in mature forest. Secondary and mature forests both presented correlations to monthly precipitation and maximum and minimum temperatures, indicating strong seasonality. However, litterfall production in the passive and active treatments was continuous throughout the year. Basal area and tree density were higher under active compared to passive restoration. Although the dominant tree species were similar under passive and active restoration, active restoration presented a higher forest species recovery, while the dominance of exotic grass patches persisted under passive restoration. The results suggest that litterfall production can be a useful and accurate indicator with which to evaluate the recovery of ecosystem function, while flower and fruit component can indicate reproductive recovery. Although litterfall production increased rapidly after five years, it did not present a seasonal dynamic. This is probably due to the fact that the species composition still differs from that of the reference systems. Evaluations of cloud forest restoration success should therefore include temporal assessments of vegetation structure and biodiversity recovery in relation to the reference forests in order to establish additional restoration techniques, particularly in the case of passive restoration strategies.
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There is a noted lack of information on the effectiveness of investments in forest fire management in Brazil. Here, we quantify the budget expenditures of one private and one public fire-management program. We then compare burned areas within conservation units (CUs) and private rural properties (PPs) with and without investments in fire management in the Brazilian Amazon and Cerrado biomes. Investments in fire management in CUs total US$ 0.51 ha⁻¹ yr⁻¹ in the Amazon and US$ 5.32 ha⁻¹ yr⁻¹ in the Cerrado. Roughly, 94% of the public investment in fire management in CUs is only assigned to suppression activities, although seven CUs in Cerrado have undertaken innovative Integrated Fire Management (IFM) that includes prevention practices. Cerrado CUs with brigades for fire suppression have reduced burned area by 12%, on average, compared with CUs without brigades. Further, CUs that also included prevention practices as part of IFM reduced burned areas by an additional 6% from CUs with only fire suppression practices. Investments in both fire prevention and suppression on private lands amounted to US$ 15.89 ha⁻¹ yr⁻¹. We identify a reduction of 50%, on average, in burned areas after PPs joined the fire mitigation program of Aliança da Terra. In face of increasingly disruptive wildfires alongside finite financial resources, we call for the need of a mix of cost-effective private and public fire management programs with strong emphasis on prevention practices.
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Contrasting responses of seed germination to fire have been reported in different vegetation worldwide. In Brazil, the Pantanal harbors one of the world's most extensive floodplains, marked by flooding periods alternating with a dry fire-prone season. The present study aimed to understand the role of fire on regeneration from seed in the Pantanal wetland, using two pioneer species displaying physically dormant seeds as study models: Sesbania virgata (Cav.) Pers. and Guazuma ulmifolia Lam. Seeds were subjected to (1) heat shocks and (2) experimental burns, besides the controls. In Experiment 1, heat shocks of 65, 85, 105, 125, and 145°C (all treatments ± 5°C), were applied for 5 minutes of exposure. In Experiment 2, seeds and corky fruits were placed upon the soil surface, and seeds were buried at 2 cm belowground, then subjected to experimental burns. Germination trials were conducted under optimal conditions and recorded the proportions of germinated, hard, and dead seeds. Increasing temperature of heat shocks had an increasingly negative effect on seed water content and germination of both species as well as increasing the proportion of dead seeds. A slight enhancement in germination of buried seeds (18%) was found in the experimental burns for S. virgata seeds. Moreover, buried seeds remained hard (dormant) up to 80 and 40% for S. virgata and G. ulmifolia, respectively. Inside the corky fruits, seed germination was not promoted and there was a decrease in the proportion of hard seeds after burning, while direct exposure to fire killed nearly all seeds placed upon the soil surface. Fire has little to no effect on the enhancement of seed germination, but seeds mainly survive when buried belowground. Our study provides crucial information to understand seed tolerance to increased fire occurrence in disturbed tropical wetlands.
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
Trans­plan­ta­tion of nat­u­rally re­gen­er­at­ing seedlings (here­after wildlings) has great po­ten­tial as a restora­tion tool as it in­volves the use of ac­cli­ma­tized in­di­vid­u­als and preser­va­tion of lo­cal and en­demic geno­types. When suc­cess­fully used, this tech­nique has the added ben­e­fits of in­creas­ing struc­tural and com­po­si­tional di­ver­sity, pre­serv­ing lo­cal and en­demic geno­types, and re­duc­ing eco­log­i­cal restora­tion costs. In wet­land ecosys­tems, flood­ing is an abi­otic fil­ter that may hin­der suc­cess of restora­tion ef­forts. We hy­poth­e­sized that trans­plant­ing “eco­log­i­cally tough­ened” wildlings from low-ly­ing, flooded ar­eas into restora­tion ar­eas of higher re­lief and lower fre­quency of flood­ing, would be a suc­cess­ful strat­egy. In this study, we trans­planted wildlings from pe­ri­od­i­cally flooded ar­eas up­s­lope to test the ef­fect of topo­graphic po­si­tion (where they were col­lected and out­planted), and pro­tec­tion against her­bivory on seedling sur­vival and growth. The ex­per­i­men­tal de­sign in­cluded two col­lec­tion times and plant­ing ar­eas (high and low topog­ra­phy), two seedling height, use of pro­tec­tion against mam­malian her­bivory, and four species that rep­re­sent dif­fer­ent func­tional types. We also eval­u­ated the costs in­volved. The best ex­per­i­men­tal out­come for the four study species (most abun­dance flood­plain species) was found with small seedlings (10–39 cm) col­lected at low re­lief and out­planted to higher el­e­va­tions, with pro­tec­tion against her­bivory. Even un­der un­usu­ally ex­treme flood events (high flood­ing over 7 months) the tree legume Inga vera has emerged with the high­est sur­vival rate. The costs of trans­plan­ta­tion are lower (USD 739 ha−1) than those found in pre­vi­ous stud­ies and the use of pro­tec­tion against her­bivory was also con­sid­er­ably low (USD 2484 ha−1). That said, these es­ti­mated costs are on an ex­per­i­men­tal scale and do not rep­re­sent large-scale op­er­a­tions, which could re­duce and im­prove cost-ben­e­fits sig­nif­i­cantly. In re­mote places such as the Pan­tanal, the lack of nurs­ery in­fra­struc­ture, high as­so­ci­ated costs of seedling pro­duc­tion and vul­ner­a­bil­ity to her­bivory are the main chal­lenges for restora­tion. Hence, wildling col­lec­tion can be a use­ful strat­egy to over­come such ob­sta­cles.
Article
Infernos in South America’s Pantanal region have burnt twice the area of California’s fires this year. Researchers fear the rare ecosystem will never recover. Researchers fear South America’s Pantanal region will never recover.
Article
The 2019–2020 megafires in Australia brought a tragic loss of human life and the most dramatic loss of habitat for threatened species and devastation of ecological communities in postcolonial history. What must be done now to keep impacted species from extinction? What can be done to avoid a repeat of the impacts of such devastating bushfires? Here, we describe hard-won lessons that may also be of global relevance.
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Degradation affects approximately three-quarters of the global wetland area. Depending on degradation drivers, resilience level, and environmental filters, different ecological restoration techniques are recommendable. The scope of this chapter is broadening the current analysis of the restoration effort made in Pantanal wetlands. We intended to include all available restoration studies in the Pantanal and discuss current public policies. In this context, we firstly reviewed restoration studies worldwide pointing some trends and gaps in wetlands. Then, focusing on the Pantanal, we discuss a recent map of the Brazilian biomes showing areas of low and high resilience, the latter being faster to restore. Next, we show a synthesis of our studies on active and passive restoration conducted in the Pantanal plain and surrounding uplands. We warn that a previous diagnosis of the restorability is crucial to choose proper techniques related to resilience level. In a 2-month flood simulation trial, all 13 studied species survived, only two had decreased root biomass, height, and diameter. Passive restoration (i.e., natural regeneration) of degraded areas in the Nhecolândia subregion takes 30 years; it is the cheapest and most efficient method if there is resilience. In contrast, direct sowing of ten tree species was ineffective, owing to inefficient pre- and post-sowing control of competitive exotic grasses, with only ten plants/ha of three species; the tallest was Sterculia apetala (2-3 m) compared with Dipteryx alata and Vitex cymosa (1.3 m each). A third experiment focused on transplanting seedlings of four riparian species (Attalea phalerata, Inga vera, Ocotea diospyrifolia and Psychotria carthagenensis). They had 0-80% survival after six months flood, depending on species, seedling size-class, flood levels of collecting or planting points, and anti-herbivory protection; tree shelters highly increased survival. Finally, another study tested nucleation with topsoil transfer and artificial perches; the first species to fruit were Croton urucurana and Trema micrantha. Examples shown can be useful for planning, implementation, and monitoring ecological restoration in the Pantanal, as well as for understanding new challenges and opportunities.
Article
Human activities in the highlands alter the usual ecohydrological dynamics of the Pantanal wetland in the lowlands. These alterations can be noted by historical observation and identification of key processes that change the normal ecohydrology in the highlands and lowlands. Depending on land-use scenarios in the near future, the ongoing changes in the highlands may have positive or deleterious effects on the Pantanal's carrying capacity and resilience for providing ecosystem services such as nutrient retention and recycling, water purification, fish stocks, among others. This article seeks to summarize recent information to clarify, guide and provide support for the pursuit of realistic scenarios and induce scientific research and government policies that reconcile sustainable development in the highlands and lowlands, in line with the conservation of the Pantanal wetland.