Bioinvasão em florestas secundárias e avaliação da madeira para o uso energético de Pittosporum undulatum Vent.

Abstract

Invasive alien species are considered the second largest cause of biodiversity loss in the world. Pittosporum undulatum Vent, native to Southwest Australia, was introduced in Brazil for ornamental purposes and is now considered invasive in several states. Management of alien species is highly costly and it is essential to add value to the managed bioinvasive species, combining management and control costs with economic return. The objective of this work was to evaluate floristic and structural diversity of forest fragments with and without bioinvasion, as well as to provide subsidies for P. undulatum wood as an energy alternative. A phytosociological survey was carried out in two fragments (reference fragment and altered fragment) of seasonal semideciduous forest at different stages of regeneration and degree of bioinvasion, in addition to evaluation of dendrological, environmental and diversity variables. Wood Technical proprieties was evaluated using Density of wood, Calorific Power and Thermogravimetry (TGA). In the phytosociological survey, 7,554 individuals from 35 botanical families and 87 tree and tree species were sampled. Pittosporum undulatum was the most important species in adult and young stages. The Altered Fragment showed higher values of richness, basal area, density of individuals, canopy opening and diversity. The similarity between fragments was 0.61 (Jaccard) and 0.55 (Morisita-Horn). Despite high bioinvasion of species, it did not changed fragment's richness and diversity, presenting values higher than several native fragments in the region. There was a decrease in the basal area as the successional stage progresses, being abnormal for fragments of the Atlantic forest. The presence of the P. undulatum in the Reference Fragment alerts to a possible bioinvasion process in older forests, mainly after disturbances. The P. undulatum wood presented Density of 0.57 g cm-3 and Superior Calorific Power of 4512.263 kcal kg-1, superior to some wood traditionally used for energy. The TGA showed lower thermal stability than other species. The species presented itself as an energy alternative for farmers in the region, being able to combine management with income generation.