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| Author(s): |
Vagner Augusto Zanzarini
Total Authors: 1
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| Document type: | Master's Dissertation |
| Press: | Rio Claro. 2020-01-27. |
| Institution: | Universidade Estadual Paulista (Unesp). Instituto de Biociências. Rio Claro |
| Defense date: | 2019-11-29 |
| Advisor: | Alessandra Tomaselli Fidelis |
| Abstract | |
Savanna ecosystems are essentially covered by herbaceous species, mostly C4 grasses, which have a huge expansion million years ago, altering the fire occurrence in the sub and tropical regions of the world. Therefore, fire-prone ecosystems as the Cerrado, have fire present about 4 million years ago, which selected species with flammable traits enhancing the flames propagation. That capacity that several species possess to be consumed and spread the fire is called flammability, which is an essential component of flammable systems, contributing to fire regime, together with environmental factors, as seasonality and species composition. Thus, this study had the main aim understand the flammability of herbaceous species of the Cerrado open savannas physiognomies, besides understand which are the species groups and traits that most influence the system flammability, according to seasonality. Different species of forbs, shrubs and graminoids were collected in areas of Cerrado campo-sujo during the wet season and over the dry season (early, mid and late-dry). Flammability (maximum temperatures, burning rate and burnt biomass) and morphophysiological traits (dead biomass, moisture content and specific leaf area) measurements were taken across seasons, to understand the flammability changes. Moreover, 21 grass species were also collected in the middle of the dry season in two different regions of Cerrado campo-sujo, where the same traits were measured, to evaluate the variability of flammability among grass species, besides understand which is the plant trait that most increase the flammability. We conclude that grasses significantly influence the open savannas flammability, especially in the middle of the dry season, when the group reached the highest flammability, while forbs and shrubs have low flammability in all seasons. Grasses showed this variability across seasons due to changes in the quantity of dead biomass and moisture content, which were considered strongly flammability influencers. Finally, we observed that grasses did not burn at the same way, having species less flammable than others in the system. Indeed, we concluded that the dead biomass percentage was the most increased flammability. In conclusion, the grass presence is indispensable in the open savanna systems, as the Cerrado, besides affect the fire regime, maintaining the open physiognomies characteristics, making that forbs and shrubs species burn and persist in the community. (AU) | |
| FAPESP's process: | 17/09914-6 - Flammability of Cerrado |
| Grantee: | Vagner Augusto Zanzarini |
| Support Opportunities: | Scholarships in Brazil - Master |