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

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INTRODUCTION
In tropical forests, lianas are important component playing an essential ecological role in
many aspects. Over the past two decades has been an increasing interest and awareness for
this growth form, although it is still poorly understood in many aspects (Gentry, 1991;
Schnitzer & Bongers, 2002; Pérez-Salicrup, Schnitzer & Putz, 2004; Gerwing et al., 2006).
Little attention has been spent on anatomy of lianas (Carlquist, 1985; Bamber & Ter Welle,
1994) and almost none to growth rings in lianas, which few papers report this feature and it is
not focused on researches (Baas & Schweingruber, 1987; Gasson & Dobbins, 1991; Carlquist,
1995; Araque, De Pernía & León, 2000). Information about growth rings in trees is
accessible, but from others growth forms is scarce. Schweingruber & Poschlod (2005) widely
studied growth rings in herbs and shrubs, and they report distinct growth rings on these other
growth forms.
In the last decades, many dendrochronologic studies in tropical tree species did report
occurrence of seasonal growth rings, correlated with some climatic variations (Mariaux, 1981;
Villalba, Boninsegna & Holmes, 1985; Détienne, 1989; Worbes, 1989, 1995; Buckley et al.,
1995; Devall, Parresol & Wright, 1995; Gourlay, 1995a, 1995b; Heinrich & Banks, 2006;
Westbrook, Guilserson & Colinvaux, 2006). In Brazil, some studies were developed in the
Amazon forest (Botosso, 1984; Worbes, 1985; Vetter & Botosso, 1989) and in the Atlantic
forest biomes (Seitz & Kanninen, 1989; Callado et al., 2001a, 2001b, 2004; Marcati,
Angyalossy & Evert, 2006). The overview of tree-ring research in tropics is given by Worbes
(2002).
Lianas are woody climbers which development begins on the ground but their ability to selfsupport
is lost with the growth; they need a support to ascend to canopy and they are able to
grow in mature forests (Gentry, 1991; Gerwing et al., 2006). Most of lianas shows cambial
variants and a few parts have stem anatomy similar of those observed on trees and shrubs, in
which the cambium is single and cylindrical and produces internally secondary xylem and
externally secondary phloem, with alike amount in all portions of stem (Carlquist, 1991,
2001; Caballé, 1993). However, it follows anatomical tendencies correlated to habit, e.g.
higher conductive area and low proportion of supporting tissues (Carlquist, 1991).
Lianas are an important structural component of tropical forests and represent around of 25 %
in abundance and species richness (Gentry, 1991; Schnitzer & Bongers, 2002; Pérez-Salicrup
et al., 2004). Leguminosae is the third largest family of climbers in the New World and with
Bignoniaceae they are dominant climbing families in neotropical lowland forests (Gentry,