Morfologia de propágulos e regeneração natural de árvores de várzea exploradas no estuário amazônico: virola, andiroba, e macacaúba

Abstract

This study evaluated the adults, seedlings, fruits and seeds morphology, germination and natural regeneration of Virola surinamensis (Rol. Rottb ex.) Warb. (Myristicaceae), Carapa guianensis Aubl. (Meliaceae) and Platymiscium pinnatum var. ulei (Harms)Klitg. (Fabaceae).Study area is located in Mazagão city, in the Florestam project localities. For morphological descriptions, we harvested branches with mature fruits from inventory trees. Adults dendrological descriptions and photographic records were made at harvest. Then, was made fruits and seeds biometrics (n=30) and descriptions. After that, seeds were sown in plastic trays with sterilized sand and vermiculite. The trays were monitored daily was done to evaluate germination parameters (germinability, germination mean time, seedling formation and germination speed index). The natural regeneration was evaluated in 240 permanent plots (10x25m) distributed along 4 transects (1000 m each) in each of 3 study areas. Were inventoried all individuals with high larger than 0,50 m to 5 cm DBH. V. surinamensis branches are horizontal and verticilate, trunk base with small buttresses, or with adventitious roots. Fruits are coccum type, globoids, yellowish green; seeds are also globoids and have red aryl; with 40% germination (epigeal cryptocotyledonary). C. guianensis has a straight trunk, irregular canopy; fruit is capsule, globose; asymmetric seed with 80% germination and cryptocotylar hypogeal seedling. P. pinnatum var. ulei has samara fruit type, dry, oblong and seeds are also oblong; 60% germination and seedling phanero epigaeous with reserve green cotyledons. The main features that differ seedlings from adults and assist in their identification are: V. surinamensis: spiral phyllotaxis, exudate presence, seedlings have the abaxial leaf lamina more whitish than adults, which, have more rusty color due the trichomes. The seed is stuck in the seedling stem on the ground for a long period. C. guianensis: nectar glands in pulvini and dark green glands in the seedlings leaves. In mature leaves, the glands are blackened. P. pinnatum var. ulei: coumarin odor, variation in phyllotaxy over the seedling, stipules interpetiolar on single sheets, whereas mature leaves are comprised. The overall average of regenerating individuals per species in the three regions was 50 ind. ha-1 for andiroba, 46 ind. ha-1 for virola and 13 ind. ha-1 for macacaúba. There was average density variation of regenerating individuals depending on the region, and P. pinnatum var. ulei had the lowest density of regenerating in all regions. There was no correlation between adult presence and seedling density. Species have propagules adapted to hydrochory, that may explain the association lack with adults. V. surinamensis and C. guianensis showed good natural regeneration levels and abundant populations, and may even have benefited from the gaps by the intense exploitation of these species in Amazon river estuary floodplain forest