Auto-ecologia de espécies de couratari (Lecythidaceae): uma abordagem para o manejo e conservação

Abstract

“Tauaris” are trees which belong to Lecythidaceae and are among the most logged timber species of Amazonia. However, their auto-ecology is poorly known, partly due to the use of only a few local names for all the species. This study defines, firstly, tauari species that occur in non-flooded forests of Amazonia and their patterns of abundance and geographic distribution. Then it characterizes regeneration aspects through functional morphology and biometry of fruits and seeds and germination physiology. Finally, the study defines the growth strategies of trees (DBH>10 cm). Data from herbaria and from >400 ha of inventory throughout the Amazonian biome were used to characterize the geographic ranges and the species abundances. Morpho-functional descriptions of fruits and seeds were based on material collected from trees of Central Amazonia (Manaus and Belterra, Brazil). The morphology of germination was described from experiments in the nursery. The physiology of germination was based on tests of seed tolerance to dessication, photoblastism and germination at different constant temperatures between 15 and 35 ° C. Growth strategies were defined through anual growth rates (average and maximum) based on 25-years monitoring in two forests logged under several cutting intensities (Paracou, French Guina; Belterra-Pará, Brazil). The tauari group consists of 14 species of the three genus. Nine were invetoried in the study areas. Couratari guianensis has the largest geographic range and is most frequent in inventories, however always with low densities (<1 tree/ha). Couratari stellata, C. multiflora, C. oblongifolia and Cariniana micrantha showed large geographical ranges (>1.10^6 km2), high frequencies and medium/high densities. Couratari atrovinosa, C. longipedicellata and C. tauari showed low abundances and regional or restricted ranges. The study provides new information about carpologia of poorly collected species (C. atrovinosa, C. tauari, C. longipedicellata) and the first description of the fruit of C. atrovinosa. For five simpatric Couratari species fo Central Amazonia, biometric measurements pointed out the need for a revision of the sections and / or a the variables of the fruit that determine each section. The slow drying of the fruit allows a gradual dispersal of seeds, unique among Lecythidaceae. Seedlings of the five Couratari species with foliaceous cotyledons and photosynthetic reserves in the hypocotyl are a rare morpho-functional type. The hypocotyl, folded below the insertion of the cotyledons, is a type that was still not documented. The seeds of each species showed desiccation tolerance, since germinated after reaching 7.9%, or less, of seed water content. Germination occurred in light and dark. C. guianensis and C. stellata had high germination rates at constant temperatures between 15 to 35 °C while C. longipedicellata and C. atrovinosa germinated significantly less below 20 °C and above 25 °C. The five species can be separated by the seed dispersal period (dry or rainy season). Temperature of 25 °C was appropriate for evaluation of seed quality of the five species. The group has characteristics that help management of seeds and species propagation species such as desiccation tolerance, fast germination, in every light conditions and temperature of 25 °C appropriate for seed quality evaluation. Growth strategies, described for Couratari guianensis, C. multiflora and C. stellata, were specific to each one and related to wood density and maximum size of the adults. C. stellata, emergent, had a weak growth potential (GP) in sub-canopy and much higher above (DAP 10-19 cm: 4 mm/ano; >30 cm: 16 mm/ano) and high growth rates for the largest adults (dbh>30 cm; 4,6-5,9 cm/year). In contrast, C. multiflora, lower canopy species, had a GP negatively correlated to tree size and the lowest average growth rate for adults (dbh>30 cm; 1,8-2,3 mm/year). Logging stimulated the growth of the three species during 15 years and growth increased with logging intensity. The growth of C. multiflora was positively correlated to the intensity of the dry season. The different growth strategies of the three species have consequences on the forest management. This work allowed to classify the species studied of Couratari as late secondary species.