Contribution to the discussions on the origin of the cerrado biome: Brazilian savanna

Abstract

Theories that attempt to explain the origin of the cerrado biome are mostly based on the isolated action of three major factors: climate, fire and soil. Another factor that has been mentioned is that of human interference. We hypothesise that the evolutionary origin of this biome resulted from the complex interaction of climate, fire and soil, with climate being the triggering agent of this assumed interaction. Fire, as well as acid and dystrophic soils, would be factors involved in the selection of savanna species throughout climatic events, during the Tertiary and the Quaternary, e.g. Pliocene and Pleistocene. The genesis of the physiognomies that would give rise to cerrado sensu lato, rather than forest formations, could have occurred due to the strong pressure exerted by the reduction in water availability, and the selection of the species adapted to the new conditions imposed by the environment. The characteristics of cerrado sensu lato soil, originated from edaphic impoverishment caused by lixiviation and successive past fires, would remain, even after hydric availability increased following the Pleistocene glaciations.Keywords: climate, fire, ecotypes, refugia, soil. Contribuição às discussões sobre a origem do bioma cerrado: savana brasileira ResumoTeorias que tentam explicar a origem do bioma cerrado baseiam-se, principalmente, na ação isolada de três fatores principais: o clima, o fogo e o solo. Outro fator mencionado ainda é a interferência humana. Quanto à origem evolutiva desse bioma, o presente estudo propõe uma hipótese que considerou a complexa interação dos três primeiros fatores, mencionados acima, considerando o clima como elemento desencadeador dessa possível interação. O fogo e solos ácidos e distróficos teriam atuado como fatores de seleção de espécies savânicas, ao longo das oscilações climá-ticas durante o terciário e o quaternário, e.g. Plioceno e Pleistoceno. A gênese das fisionomias que passariam a compor o chamado cerrado sensu lato, em detrimento de formações florestais, teria resultado da forte pressão exercida pela redução da disponibilidade hídrica e da seleção de espécies adaptadas às novas condições impostas pelo ambiente. As características do solo, que passariam a manter o cerrado sensu lato, oriundas do empobrecimento edáfico pela lixiviação e sucessivos incêndios pretéritos, permaneceriam, mesmo com o restabelecimento de uma maior disponibilidade hídrica, após as glaciações do Pleistoceno.

Will we have enough to eat in the near future?: what the Brazilian Society of Plant Physiology and The Global Plant Council have to do with it?

“…Therefore, given this scenario, why not investigating these native plants in order to understand their Al metabolism and Al-related genes? After all, these species have been growing on these acidic soils from Cerrado areas for more than 60 millions years (Pinheiro and Monteiro 2010). But agronomists also consider Al toxicity to be partially resolved, as lime (CaCO 3 and MgCO 3 ) application reduces Al in the soil, increases soil base saturation and elevates the pH in the soil.…”

Towards a New Ecophysiological Approach to Understand Citrus Crop Yield Under Abiotic Stresses Mirroring in the Brazilian Savanna Genetic Resources

“…It would be easy to inaccurately justify devastation of cerrado areas to be used for citrus plantations. However, the cerrado vegetation is considered to have been selected under an important pressure of dry/wet seasons (Pinheiro and Monteiro, 2010). Consequently, the main constraint for cerrado woody species during the wet season is a nutritional stress, as soil nutrients are leached to soil beds after heavy rains, while in the dry season the lack of water availability to roots becomes the main concern.…”

“…plantations. Cerrado plants have been facing biotic and abiotic stresses for millions of years, and adaptive pressures have always been applied to them (Pinheiro and Monteiro, 2010). Interestingly, the 'Rangpur' lime is considered to be the best rootstock species for regions subjected to severe environmental stresses, such as the northern and northwestern regions of São Paulo state.…”

“…Indeed, Haridasan (2008) highlights the importance of understanding different aspects of plant biology of several species from the cerrado vegetation. Since severe wet and dry seasonal events may have been one of the most important pressures for the new savanna vegetation that formed during the Tertiary and Quaternary geological eras (Pinheiro & Monteiro, 2010), it is expected that cerrado species present very good adaptations to cope with these pressures. In general, cerrado species present long and deep root systems (Rawistscher 1948;Franco 1998;Habermann & Bressan, 2011), low specific leaf areas (SLA) and thick leaves, especially in evergreen species (Franco et al, 2005).…”

Non-destructive equations to estimate the leaf area of Styrax pohlii and Styrax ferrugineus

“…The Brazilian savanna (Cerrado) is comprised of a mosaic of biomes, from savanna vegetation to gallery forests (Batalha, 2011;Pinheiro and Monteiro, 2010) that originally covered 21% of the Brazilian territory (Souza and Habermann, 2012). Because of human activities (mainly agriculture), the Cerrado has been drastically fragmented, and less than 34% of its original area still remains (Klink and Machado, 2005).…”