1. Dendrochronological potential of Ocotea notata (Nees & Mart
Dendrochronological potential of Ocotea notata (Nees & Mart.) Mez (LAURACEAE), “TABULEIRO” ATLANTIC FOREST, espírito santo, brasil
Cláudia Fontana¹, Gabriela Morais Olmedo², Paulo César Botosso³,
Alessandra Nunes de Amorin4 & Juliano Morales de Oliveira5
1 Postgraduate Program in Biology, University of Vale do Rio dos Sinos (UNISINOS); 2, 4Graduate students in Biology, UNISINOS; 3Researcher, Empresa Brasileira de Pesquisa Agropecuária (Embrapa Florestas); 5Professor, Postgraduate Program in Biology, UNISINOS.
Introduction
Results and Discussions
Annual growth periodicity is a fundamental premise in dendrochronology. In tropical forests, although subjected to more homogeneous intra-annual temperature conditions than their temperate counterparts, annual precipitation regimes are know to induce the formation of annual growth rings in woody species. Here we aim to evaluate the dendrochronological potential of Ocotea notata trees growing in “Tabuleiro” Atlantic Forest, by examining the appearance, crossdating and climatic signals of its growth layers.
Growth zones were delimited by layers of flattened and thick walled fibers, but density fluctuations were commonly observed too (Fig 2). The correlation of growth series among trees suggest these growth zones may be formed in annual basis (Fig 3). Climatic signals were not evidenced, however.
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Figure 2: Pattern of growth rings observed in Ocotea notata.
100 µm
500 µm
Materials and Methods
We build a ring-width chronology with four Ocotea notata trees, sampled at Natural Reserve of Vale do Rio Doce (18oS; 39oW).
Figure 3: Standard index per tree (gray) and master chronology (black) .
rbar=0.292
Samples were obtained with increment borer (Ø5mm) and submitted to polishing, dating and measuring of growth rings, followed by visual and numerical cross-dating. To reduce ontogenetic variation in the growth ring series we ued cubic smoothing spline functions. Standard chronology was correlated (Pearson) with meteorological reccords of mothly mean temperature and total precipitation (BDMEP databank; Fig 1).
Conclusions
Ocotea notata form distinct growth layers with a reasonable synchronicity among trees, likely to correspond to annual growth rings, but intra-annual density fluctuations may hinder correct dating and climatic signal identification. Its dendrochronological potential needs further investigation.
Acknowledgements
Figure 1: Climatic diagram for the study region, showing seasonal precipitation regime.