Human-climate interactions shape fire regimes in the Cerrado of São Paulo state, Brazil

Conciani, Dhemerson; Santos, Lucas Pereira dos; Silva, Thiago Sanna Freire; Durigan, Giselda; Alvarado, Swanni T.

doi:10.1016/j.jnc.2021.126006

Cited by 21 publications

(10 citation statements)

References 51 publications

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“…Mean annual temperature ranges from 18 to 22°C. The vegetation at SBES is composed of open grasslands, savannas and forests (Melo & Durigan, 2011), with varying grass cover and fire frequencies and severity (see Table S1 for details of fire frequencies during 1984–2019; Conciani et al., 2021). Woody vegetation can be classified into four physiognomies: open savannas, woody savannas, cerradão (a forest composed of generalists and forest tree species, where fire occurrence is rare due to the lack of a grass layer and flammable components; Coutinho, 1990; Newberry et al., 2020) and seasonally semideciduous forests (a fire‐sensitive vegetation with deciduous trees, Figure 1).…”

Section: Methodsmentioning

confidence: 99%

“…The sampled plots in open savannas burned nine times in the last 34 years, and the last fire was in 2016 (Figure S2a), which led to a high accumulation of fuel load. The sampled plots in woody savanna burned two times during the same period, and the last fire occurred in 2011 before the firestorm (Figure S2b; Conciani et al., 2021). This firestorm lasted c .…”

Section: Methodsmentioning

confidence: 99%

Section: Study Sitementioning

confidence: 99%

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Your best buds are worth protecting: Variation in bud protection in a fire‐prone cerrado system

et al. 2021

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1. Species growing in fire-prone savannas usually persist by resprouting from their buds. In this study, we evaluated how various persistence traits allow bud protection for improved survival in fire-prone ecosystems.2. Using an integrative morphological and macroanatomical approach, we analysed how woody plants protect their buds. We tested bud protection at the community level and evaluated: (a) how bud protection changes along a fire frequency gradient, (b) if it differs between shrubs and trees and (c) whether the level of bud protection is related to post-fire responses of 28 woody savanna species.3. A mix of traits involving bud protection may enable woody species persistence in fire-prone ecosystems. Savanna species better protected their buds than forest species by developing bark and trichomes that allowed resprouting after fire.Regarding growth forms, shrub species capable of resprouting above-ground had their buds better protected than trees.4. Bud protection is not only linked with their position to the bark, but also with the presence of trichomes. Profuse trichomes covering buds were related to savanna species. Some species with no bud protection by bark but with trichomes covering their buds were able to resprout after fire. The presence of accessory buds is also a trait more related to savannas, possibly influencing the resprouting after fire as they are better protected and increase the bud bank. Finally, different persistence traits interact with one another to better protect the buds, requiring a detailed screening of the traits to assess species responses to fire. Synthesis.During fire, species have their aerial biomass consumed by the flames.To be able to resprout new branches and persist in the environment, they must have well-protected buds. In this study, we evaluated different ways that woody species protect their buds and related them with their resprouting strategy after fire. We investigated the protection by the bark, the presence of trichomes and accessory buds. By studying the woody community in a gradient of savannas and forests we found that buds can be protected by bark, trichomes or soil. Species can present a mix of these traits and strategies, which enhances their resprouting after fire.

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Section: Methodsmentioning

confidence: 99%

Section: Methodsmentioning

confidence: 99%

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Your best buds are worth protecting: Variation in bud protection in a fire‐prone cerrado system

et al. 2021

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“…At present, the reserve is a mosaic of grassland, savanna and forest. At the time of sampling (2015), none of the sampled sites had been burned more than twice since 1985 (fire scars obtained from Landsat images by Concianni et al., 2021).…”

Section: Methodsmentioning

confidence: 99%

Facilitation by isolated trees triggers woody encroachment and a biome shift at the savanna–forest transition

Abreu

Durigan

Melo

et al. 2021

Journal of Applied Ecology

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1. Woody encroachment into grassy biomes is a global phenomenon, often resulting in a nearly complete turnover of species, with savanna specialists being replaced by forest-adapted species. Understanding the mechanisms involved in this change is important for devising strategies for managing savannas.2. We examined how isolated trees favour woody encroachment and species turnover by overcoming dispersal limitation and environmental filtering. In a savanna released from fire in south-eastern Brazil (Cerrado), we sampled woody plants establishing under 40 tree canopies and in paired treeless plots. These trees comprised eight species selected for habitat preference (savanna or forest) and dispersal syndrome (bird dispersed or not). We recorded dimensions of each tree, dispersal syndrome and habitat preference of recruits, and quantified the physical environment within each plot, aiming at a mechanistic understanding of woody encroachment.3. We found clear evidence that isolated trees cause nucleation and drive changes in functional composition of savanna. Effectiveness as nucleator differed among species, but was unrelated to their functional guilds (habitat preference or dispersal syndrome). The density of saplings in nuclei was partially explained by soil moisture (+), daily temperature amplitude (−) and sum of bases (−). 4. Our results indicate that isolated trees act first as perches, strongly favouring bird-dispersed species. They then act as nurse trees, considerably changing the environment in favour of forest-adapted recruits. In the long term, as the nuclei expand and merge, savanna specialists tend to disappear and the savanna turns into a low-diversity forest. Synthesis and applications.Fire suppression has allowed the nucleation process and consequently the woody encroachment and fast replacement of savanna specialists by forest species in the Cerrado. By elucidating the mechanisms behind woody encroachment, we recommend using prescribed fires to burn forest seedlings and to reduce tree canopy size wherever the management goal is to maintain the typical savanna structure and composition.

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“…One "campo cerrado" patch had only one fire event recorded in the last 30 years, in 2001, and the other patch in 2011, and both have been under fire suppression since then. The other plots that were sampled, burned for the last time before 1985 (Melo and Durigan, 2011;Conciani et al, 2021). Although these sparse fire events contributed to the grasslands maintenance in the area, SBES have been suffering under woody encroachment across this period (Melo and Durigan, 2011;Abreu et al, 2017Abreu et al, , 2021.…”

Section: Study Areamentioning

confidence: 99%

Winners and Losers: How Woody Encroachment Is Changing the Small Mammal Community Structure in a Neotropical Savanna

et al. 2021

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Years of fire suppression, decreases in herbivores, and global climate change have led to shifts in savannas worldwide. Natural open vegetation such as grasslands and shrublands is increasing in wood density, but the effects for small mammals are not well understood. While most of the mammal studies from the Brazilian Cerrado are concentrated in the core area of this large Neotropical savanna, its southern portions are suffering from biome shifting through woody encroachment. Herein, we surveyed a small mammal community from the southeastern boundary of Cerrado (Santa Bárbara Ecological Station) and evaluated the micro and macro environmental variables shaping community structure in order to investigate how the woody encroachment in the last 15 years may have influenced this assemblage. We recorded 17 species of marsupials and rodents along five distinct habitats in a gradient from grasslands to woodlands. Although richness was not affected by microhabitat variables, total and relative abundance varied according to habitat type and in relation to herbaceous, shrub, and tree density. Rodents such as Calomys tener and Clyomys laticeps were positively affected by increasing herb cover, Cerradomys scotti and Oligoryzomys nigripes by shrub cover, while the marsupial Didelphis albiventris had higher association with increasing tree cover. We detected an increase of 27.4% in vegetation density (EVI) between 2003 and 2018 in our study site, and this woody encroachment negatively affected the abundance of some small mammals. The open-area specialists Cryptonanus chacoensis and C. scotti had a decrease in abundance, while D. albiventris and O. nigripes were favored by woody encroachment. Our data suggest that woody encroachment is shifting community composition: small mammals often associated with grasslands and open savannas are likely to be negatively affected by woody encroachment; while species that rely on tree-covered habitats are likely to benefit from an increasing woody landscape. Therefore, forest-dwellers are gradually replacing open-vegetation inhabitants. Active management of open formations (e.g., with prescribed burning) may be needed to maintain Cerrado biodiversity, especially considering the open-area endemics.

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Human-climate interactions shape fire regimes in the Cerrado of São Paulo state, Brazil

Cited by 21 publications

References 51 publications

Your best buds are worth protecting: Variation in bud protection in a fire‐prone cerrado system

Your best buds are worth protecting: Variation in bud protection in a fire‐prone cerrado system

Facilitation by isolated trees triggers woody encroachment and a biome shift at the savanna–forest transition

Winners and Losers: How Woody Encroachment Is Changing the Small Mammal Community Structure in a Neotropical Savanna

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