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In tropical regions, coexisting savannas and forests, such as the Cerrado biome in Brazil, are exposed to similar climates. The Cerrado encompasses various vegetation types, including broad-leaved and sclerophyllous plants in dense woodland or shrubland (cerrado sensu stricto), semi-evergreen trees in closed-canopy forest (cerradão), grasslands with scattered shrubs (campo sujo), and semi-deciduous seasonal forest.
Areas of cerradão develop in the absence of fire, in both poor and moderately fertile soil (dystrophic to mesotrophic).
Botanists and ecologists are fascinated by the coexistence of savannas and forests in tropical regions, as these ecosystems harbor distinct species and exhibit unique dynamics and functions. Savannas, characterized by dense grasslands that are prone to frequent fires, have a direct impact on other types of vegetation due to their high flammability.
Forests, on the other hand, have a broad, mostly continuous canopy that provides shade for undergrowth, bushes and smaller trees, and prevents the growth of flammable grass.
Over millions of years of evolution, species in savannas have developed adaptations to withstand fire, such as thick bark that protects them from damage. Additionally, after a fire event, these species can regenerate by sprouting new branches and leaves from specialized asexual buds called gemmae. This unique ability to regenerate allows savanna vegetation to recover and thrive in the face of frequent fires, shaping their ecological dynamics and resilience to fire-prone environments.
A cutting-edge study carried out at the Santa Bárbara Ecological Station, an environmental protection unit in São Paulo state, Brazil, delved into the production of bark in savanna and forest species within the Cerrado biome, using trending keywords such as "Cerrado," "savanna," "forest," "bark production," and "gemmae protection." The study investigated whether savanna species that produce more bark also exhibit more effective gemmae protection, and whether generalist species, which occur in both savannas and forests, show differences in bark production based on their growing environment. The findings of this innovative research have been published in the esteemed journal Annals of Botany, garnering attention for their insights into the unique adaptations of Cerrado vegetation to fire-prone ecosystems and the ecological dynamics of this diverse tropical savanna-forest mosaic.
The principal investigator for the study was Alessandra Fidelis, a professor in the Department of Biodiversity at São Paulo State University’s Rio Claro Institute of Biosciences (IBRC-UNESP).
The first author of the article is Marco Antonio Chiminazzo, a PhD candidate at IBRC-UNESP.
The other co-authors are Aline Bombo, a postdoctoral fellow at IBRC-UNESP, and Tristan Charles-Dominique, a researcher at the Sorbonne in Paris and the University of Montpellier, both in France.
"We observed a fascinating pattern in our study," explained Chiminazzo, one of the lead researchers of the study, in an interview with Agência FAPESP. "Savanna species produce approximately three times as much bark as forest species, while generalist species show intermediate levels of bark production, producing more bark in savanna areas compared to forests. This ability of species to adjust their bark production based on the environment is known as phenotypic plasticity and may be a deliberate strategy for survival." Chiminazzo further elaborated, "Interestingly, we also found that species that produce more bark tend to have better protection for their gemmae and internal tissues, indicating a potential adaptive advantage in fire-prone ecosystems." These findings highlight the dynamic nature of plant responses to environmental conditions and the unique strategies employed by different species in the Cerrado biome to thrive in their respective habitats.
“Our study shows that fire is an important factor for savanna-type vegetation in the Cerrado, promoting the woody species that can cope with this disturbance and couldn’t live in shady forest areas.”
The research presents compelling findings that endorse the trending approach of controlled fire management in Cerrado savanna regions. Effective fire management involves strategic zoning and a well-planned timetable. Zoning establishes a diverse mosaic pattern for rotational burning in designated areas, in accordance with the prescribed timetable.
According to Fidelis, who serves as Chiminazzo's thesis advisor, the plant species in the Cerrado have evolved to adapt to fire through various mechanisms, such as developing thick bark and robust gemmae protection. These traits have emerged as a result of a lengthy evolutionary process, allowing the plants to withstand fires and regenerate successfully post-burning.
Remainder
The research was conducted in an ecological station located in the municipality of Águas de Santa Bárbara, which serves as a crucial native Cerrado remnant in São Paulo state, encompassing diverse savanna and forest types within the biome. Chiminazzo explained that the study involved sampling shrub and tree species from four distinct vegetation types that experienced varying frequencies of burning and light availability. The team investigated the bark production and gemmae protection mechanisms of these species as they developed, and then categorized them into three groups based on their habitat preferences: savanna specialists, forest specialists, and generalists capable of thriving in both environments.
As per Chiminazzo's insights, future research endeavors should aim to unravel the mechanisms behind why certain species are capable of adjusting their bark production while others cannot. Understanding the factors that drive these differences can provide critical insights, especially in the context of climate change and evolving fire regimes. This knowledge can help in predicting and assessing the vulnerability of different organisms to changing environmental conditions, offering a significant opportunity to safeguard and conserve species that demonstrate greater adaptability.
The study was supported by FAPESP via a Young Investigator Grant awarded to Fidelis. In addition, Chiminazzo received a master’s scholarship and a doctoral scholarship.
About São Paulo Research Foundation (FAPESP)
The São Paulo Research Foundation (FAPESP) is a public institution with the mission of supporting scientific research in all fields of knowledge by awarding scholarships, fellowships and grants to investigators linked with higher education and research institutions in the State of São Paulo, Brazil. FAPESP is aware that the very best research can only be done by working with the best researchers internationally. Therefore, it has established partnerships with funding agencies, higher education, private companies, and research organizations in other countries known for the quality of their research and has been encouraging scientists funded by its grants to further develop their international collaboration. You can learn more about FAPESP at www.fapesp.br/en and visit FAPESP news agency at www.agencia.fapesp.br/en to keep updated with the latest scientific breakthroughs FAPESP helps achieve through its many programs, awards and research centers. You may also subscribe to FAPESP news agency at http://agencia.fapesp.br/subscribe.
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