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Changes on the vegetation structure of mangroves after the construction of the Suape port (PE, Brazil)

SOUZA, Marta Maria de Almeida and SAMPAIO, Everardo V. S. B.

Abstract : To monitor the impact of the Suape (PE, Brazil) port construction on the vegetation structure of the mangroves of the area, data from 1988 and 1995 were compared, using six little disturbed sites (LD), four sites undergoing selective logging (SL), three old regeneration sites (OR) and two new regeneration sites (NR). Six plots 10 x 10m were established in each site, all plants found in those in plots had for their height and stem diameter measured. Four species were found without a well defined distribution pattern: Rhizophora mangle L., Laguncularia racemosa (L.) Gaertn., Avicennia schauerianna Stapf.& Leechman and Avicennia germinans L. Conocarpus erecta L. was present in the mangrove - sand coastal transition area. The species distribution showed no marked change between 1988 and 1995 and no differences related to disturbance situation. LD sites had a large structural diversity (density, 917-5683 plant/ha; basal area, 12.7-60.8m2/ha; average and maximum diameter, 5.6-22.4 and 12-36 cm; average and maximum height, 6.7-16.3 and 10-18m) and their changes during the period indicate that selective cutting had occurred, but no signs of that could be detected. Without periodical monitoring, they would not provide an adequate reference pattern. SL sites had visible logging marks and decreases in the densities of plants with diameter > 10cm and in basal areas. Regeneration sites after flooding or filling up with earth, before (OR) and after 1988 (NR), had height, diameter and basal area lower than those of LD and SL, but OR had the highest density (7150-11850 plant/ha). Therefore, 8 years were not enough for recovery.

Keywords : mangrove; structure; regeneration; environmental impact; Brasil.

Acta Bot. Bras., Jan./Apr. 2001, vol.15, no.1, p.1-12. (Full text available in Portuguese ).

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