Anatomia do lenho de oito espécies de lianas da família Leguminosae ocorrentes na Floresta Atlântica

Abstract

RESUMO -(Anatomia do lenho de oito espécies de lianas da família Leguminosae ocorrentes na Floresta Atlântica). Lianas são importantes componentes estruturais das florestas tropicais, apesar disso a anatomia destes vegetais é pouco estudada. A família Leguminosae é relatada como a segunda maior em número de espécies de lianas, contudo pouco se conhece da diversidade anatômica das lianas desta família. O presente estudo descreveu e analisou a anatomia do lenho de oito espécies de lianas da família Leguminosae, ocorrentes no Parque Nacional do Itatiaia, localizado no Estado do Rio de Janeiro, região Sudeste do Brasil, local inserido no bioma Floresta Atlântica. As espécies apresentaram características comuns ao hábito liana, como: elementos de vaso com diâmetro elevado, com duas categorias de diâmetro; e maior proporção de parênquima axial em comparação às fibras. Quatro espécies do gênero Senegalia apresentaram variações cambiais produzidas por um único câmbio, normal em produto mas anormal em conformação. A anatomia do lenho das espécies estudadas é muito semelhante por compartilharem o mesmo hábito e pertencerem à mesma família. Apesar disso, as oito espécies estudadas puderam ser diferenciadas. As espécies com variações cambiais e Dalbergia frutescens são facilmente diferenciadas das demais. Contudo Senegalia tenuifolia, Piptadenia micracantha e Piptadenia adiantoides necessitam ser examinadas com muita cautela para identificá-las exclusivamente pela anatomia do lenho. Palavras-chave: anatomia da madeira, lianas, Mata Atlântica, LeguminosaeABSTRACT -(Wood anatomy of eight liana species of Leguminosae family from Atlantic Rain Forest). Lianas are important structural component of tropical forests and even though the anatomy of these plants is poorly studied. Leguminosae family is reported as the second larger family in number of liana species, but little is know about the anatomical diversity of lianas from this family. The present study described and analyzed the wood anatomy of eight liana species of Leguminosae family, from Parque Nacional do Itatiaia, located in Rio de Janeiro State, Southeast region of Brazil and included in Atlantic Rain Forest Biome. The species show common features with the liana habit, as: wide vessels, vessel dimorphism, and high proportion of parenchyma when compared with fibers. Four species of Senegalia genus showed cambial variants made by a single cambium, normal in products but abnormal in conformation. The studied species have similar wood anatomy, many of which are because they belong to the same family and share the same habit. Nevertheless, the eight species studied could be distinguished. The species with cambial variants and Dalbergia frutescens are easy distinguished from the others. However Senegalia tenuifolia, Piptadenia micracantha and Piptadenia adiantoides require much wariness examination to identify the species exclusively by wood anatomical features.

Hydraulic architecture of lianas in a semiarid climate: efficiency or safety?

“…Although the vessel of the analyzed lianas does not have vestured pits, the pit diameters (approximately 1.1-1.6 μm) were much smaller than those found by Brandes & Barros (2008), which ranged from 5 to 10 μm in moist forest liana species. According to Carlquist (1988) and Metcalfe & Chalk (1989), pits with diameter smaller than 5 μm are extremely small.…”

“…In lianas, the xylem shows cambial variations that are assumed to be adaptations related to the climbing habit of these plants, including wide vessels, high proportion of parenchyma, and low amount of fibers (Carlquist 1985;Brandes & Barros 2008). Although wide vessels provide greater hydraulic conductivity to lianas than other growth forms, they may also decrease their hydraulic safety (Gartner et al 1990;Ewers et al 1997;McCulloh & Sperry 2005;Gutierréz et al 2009).…”

“…Although wide vessels provide greater hydraulic conductivity to lianas than other growth forms, they may also decrease their hydraulic safety (Gartner et al 1990;Ewers et al 1997;McCulloh & Sperry 2005;Gutierréz et al 2009). The low amount of fiber increases the flexibility of the stem (Carlquist 1985;Brandes & Barros 2008;Carlquist 2012) and decreases the risk of mechanical damage to the xylem (Carlquist 2012). On the other hand, the significant amount of parenchyma can increase the capacity to store water in the stem (Martínez-Cabrera et al 2009).…”

“…Unlike lianas, trees and shrubs that occur in semiarid habitats tend to be smaller, have short and narrow vessels, high proportion of fibers, and high WD that increases the resistance to cavitation but reduces hydraulic conductivity Hacke et al 2006;Mitchell et al 2008). Lianas are presumably sensitive to soil water depletion; however, few studies have investigated the anatomical characteristics of the hydraulic system of lianas that occur in seasonally dry environments (Brandes & Barros 2008;Pace et al 2009;Angyalossy et al 2012). In addition, although the xylem hydraulic architecture of liana roots is still unknown, it can provide important insights to explain the hydraulic functioning of liana species in semiarid zones (Carlquist 1989;Choat et al 2005;Poorter et al 2010;Gea-Izquierdo et al 2012).…”

Climbers from two rock outcrops in the semi-arid region of Brazil

“…There are few works of a floristic nature in Brazil that deal exclusively with climbing plants, of which many were conducted in the Brazilian Southeast (Weiser 2001, Hora and Soares 2002, Brandes 2007, Hora et al 2008, Barros et al 2009, Villagra and Romaniuc Neto 2010,Vargas et al 2013. Information on climbing plants for the Brazilian Northeast is scarce and mostly restricted to floristic inventories and taxonomic studies.…”