Anéis de crescimento em espécies da família Lauraceae: características anatômicas e sinais dendroclimáticos

Abstract

Tree-rings are anatomical structures formed in the secondary xylem of wood plants. These structures delimit the growth cycles and dormancy as response to seasonal climate regimes. Since each ring correspond to one annual growth cycle varying their features as result of physical and biotic conditions, these structures are unique historical records with high resolution and temporal depth reflecting environmental changes. The dendrochronology – science that investigates tree-rings in wood plants – is incipient in tropical ecosystems, taking into account its advancement in temperate zones, and should be developed in tropical zones to provide clearer information about autoecology, forest ecology and climatology, base to tropical biodiversity management. To recognize species forming visible tree-rings in their xylems and that are sensible to climatic fluctuations is the first and prime step to development of dendrochronology. In this Master Dissertation I revise and perform dendrochronological analysis in the neotropical Lauraceae family, mainly in remaining forests of Southern rain forest of Brazil, a hotspot of biodiversity. I focus my efforts in Lauraceae family due to ecological and physiognomic importance of their species to neotropical rain forests. Information about tree-rings are widely available in the scientific literature, especially in the anatomical wood researches. Most species of Lauraceae family form tree-rings in different ecosystems (139 of 156 revised species). In order to facilitate future studies and the recognition of tree-rings I present 156 species described by tree-ring appearance plus 14 other frequent species in Southern rain forest. With temporal series of tree-ring width I verify that Ocotea pulchella, Cinnamomum glaziovii and Ocotea elegans, species from subtropical montane regions of Brazil, have the same growth tendency between individuals (synchronism). Moreover, are sensible to climate variations mainly related to temperature and precipitation. The findings of this dissertation are essential to contribute to development of neotropical dendrochronology, providing a better understanding about tree-rings features of one of the most important families in the tropical regions.