anatomia do lenho e dendrocronologia de lianas da família ...

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In the last decades the knowledge about growth rings in tropics improved, but its occurrence
remains with low scientific acceptance (Worbes, 2002). This laid on concept that tropical
region lack marked seasons, which produce distinct growth rings. But the contrary had been
demonstrated in many studies, in which approximately half of species from these regions had
distinct growth rings. The same was realized in this study. Alves & Angyalossy-Alfonso
(2000) observed ecological trends in some Brazilian tree species, which detect that 48 % of
the studied species have growth rings correlated positively with mild and medium
mesothermic climates and negatively related to super-humid environments. In this study 136
species of Leguminosae family were sampled and 71 species presented distinct growth rings.
Among them, four species are of the genus Piptadenia and five of genus Dalbergia, including
D. frutescens. The interactive key for commercial timbers, from Delta Databases (Richter &
Dallwitz, 2000), indicate eleven species with distinct growth ring of 24 Leguminosae species
from tropical South America. Seven with marginal parenchyma and among them two have
semi-ring-porosity. Dalbergia decipularis Matt. & Rizz. and Piptadenia macrocarpa Benth.
are examples of tree species with distinct growth ring from tropical South America. Roig et
al. (2005) report that 42 % of the studied Leguminosae species in Yucatan Peninsula had
visible rings. These previous studies and the present study show that growth rings in
Leguminosae species, trees and lianas, from tropical region is a frequent feature.
Growth rings in lianas were detected in other studies. Gasson & Dobbins (1991) report
distinct growth rings in Bignoniaceae family, genus Capsis from tribe Tecomeae, in genus
Schlegelia from tribe Schlegelieae and in nine genera from tribe Bignonieae. Among diverse
plant habits from Europe, Baas & Schweingruber (1987) observed that climbers show porousring,
semi-ring-porous. But they do not sampled Leguminosae species and the samples
analysed were from temperate climate. In other study within lianas in Venezuela, it was
observed growth rings in Anomospermun schomburgkii Miers (Menispermaceae) and
Strycnos brachistantha Standley (Loganiaceae), marked by marginal parenchyma (Araque et
al., 2000). These two species showed diffuse porosity. Semi-ring porous and marginal
parenchyma were important features observed in lianas analysed on this study, because they
are present in all species with distinct growth ring. The growth rings are made of variation in
cambium activity and its products, and each ring may represent a period of one year (Fahn,
1982). A cambium activity study detected in four lianas from a Mexican tropical rainforest
that cambium is active along all year. Although, three species showed strong cambial
seasonality, differing by number of cambial layers, positively associated with rainfall. Two