Difference between revisions of "Attalea funifera"

Thus, Bondar (1942) and Valeriano (1934) attributed the luxuriant post-fire carpet of piassava seedlings to the stimulation of long-dormant seeds by the heat of the sun, whereas Moraes (1911) speculated that the heat of the fire directly induced germination. This paper considers the role of fire as a management tool in piassava forests, and specifically examines the validity of the seed stimulation hypothesis. Using field germination experiments, the following questions are addressed: Do piassava seeds retain viability in the soil seed bank, or do they readily germinate? And if seed dormancy exists, is there evidence that buried seeds are induced to germinate by the heat of a fire, by the nutrient flush following a fire, or by the increased access to solar radiation? Piassava is endemic to the moist tropical forests of coastal Bahia, Brazil. The mean annual precipitation, which falls equally throughout the year, is on the order of 1500-2200 mm, and the mean annual temperature ranges from 23 °to 24° C (Voeks 1987). The topography of this region is visually dominated by a series of well-eroded sea terraces, or tabuleiros. Although usually covered by deep latosolic soils, these tabuleiros are in places mantled with tropical podzols (Braun and Ramalho 1980). Porous in texture and low in exchangeable bases, these silicious podzolic soils sustain a slightly-dwarfed evergreen restinga forest, of which piassava is a common member (Silva and Vinha 1982). Piassava attains a height of 12 to 15 m, and is easily identified in the field due to the presence of 9-m-long. fronds covered with drooping, aggregated leaflets. Inflorescences consist of massive, simply branched panicles that are either male, female, or bisexual. Individual palms often change gender as they grow and reach the forest canopy, a condition associated with decreasing competition and increasing access to solar radiation (Voeks 1988a). Pollination is carried out by highly specialized beetles (Phyllotrox tatianae and Mystrops sp.), and is apparently facilitated by a flower mimicry system (Voeks 1985). Fruits weigh up to 500 gm, contain 1-3 seeds (kernels), and are much sought after by local residents who both eat the seeds raw and render them into cooking oil. Although fruits were in the past naturally dispersed by large forest rodents, over-hunting of these animals for food has for the most part eliminated this means of seed dispersal (Voeks 1987). The primary economic value of piassava is its sheath fiber. These 5-m strands of water-resistant fiber have long represented an important component of the regional export economy, first in the fashioning of anchor cables, and later in the manufacture of brooms and brushes (cf. Sousa 1938; Hooker 1849). During the twentieth century, piassava fiber exports have fallen markedly as a result of competition with plastic substitutes. Nevertheless, fiber production has risen sharply in the last few decades to meet a growing domestic demand, and at present over 60,000 tons of this raw material are extracted annually from the Bahian forests (Voeks 1988b). Although successful planting schemes have recently taken place, piassava is traditionally managed by fire. Small patches of restinga forest are burned during the summer (December-March), after all but the piassavas have been hacked down and allowed to dry. Piassava seedlings quickly emerge from these blackened, nutrient-rich soils, and become commercially productive in 5 to 8 years. Because natural forest succession of the burned site is quite gradual, management by fire need only be repeated every 50 years or so in order to maintain dense stands of this palm (Voeks 1987).

In addition: The United Nations General Assembly declared the year 2009 as the International Year of Natural Fibres (United Nations, 2006). Apart from being a sustainable alternative natural fibres are technically feasible and offer many positive social implications. Over recent years there has been an increase in the use of the leaves, fruits and fibres from the Piassava palm. In Brazil, there are three species of piassava palms; the Leopoldinia piassaba and Aphandra natalia are native from the western Amazon and the Attalea funifera Mart is from the Atlantic Forest. Attalea funifera Mart fibres can reach 5m in length, are about 1mm in diameter and are water-resistant (Aquino, D´Almeida and Monteiro, 2001, and Voecks and Vinha, 1988). Fibres from the Bahia piassaba palm have been described as harder than other lignocelulosic fibres. Piassava palms are economically valuable and are usually undomesticated. The cultivation of piassava is managed by approximately 2000 small-scale farmers, processors and their families. They have long represented a significant part of the regional export economy, as fashioning of anchor cables, and later in the manufacture of brooms and brushes. Piassava fibre exports had fallen remarkably as a result of the competition with synthetic fibres and threads. Nowadays, they are used as car seat fillings and as reinforcement in polymeric matrixes too. Residues from fibres, known as bagasse, ribbon or lees, are used as roof and industrial thermal insulation. At present over 10.000tons of these raw materials are extracted annually from the Atlantic Forest. Research in Attalea funifera Mart to reinforce polymer matrixes is still uncommon. Recently, Brazilian researchers have been investigating the piassava fibres as a possible reinforcement of polymeric based composites (Aquino, Monteiro, D´Almeida, 2003 and Bonelli et alli, 2005). Guimarães (1987) investigated the mechanical behaviour of piassava fibres and lees to reinforce cement based composites. This work compares the physical behaviour of piassava fibres and lees. 2. Piassava fibres and lees For technical purposes it is worth defining and confirming the terms used to describe the fibrous plant materials. Individual fibres contain sclerenchyma cells which provides the plant with mechanical support. Technical fibres or textile fibres are bundles of individual fibres that have mechanical properties that depend on the origin of plant, the nature of the extraction, refining procedures, age, and chemical constituents (Vincent, 2000).