Variação temporal do componente lenhoso e de cactáceas de uma área de caatinga em Betânia/PE

Abstract

Growth, recruitment and deaths of woody and cactus plants were monitored, along five years, in a caatinga community in a semiarid site, in Northeastern Brazil, with 511 mm and 25 oC average annual rainfall and temperature. All plants with stem diameter at soil level > 3 cm, within one hectare, were marked and measured in 2001 and 2006. The number of species increased from 27 to 28 and that of plants from 3142 to 3567 (13.5% increase), with an addition of 724 new plants (4.23% each year) and death of 299 plants (1.98% each year). Therefore, the community had high rates of recruitment and mortality, as has been observed in other dry areas. Plant size was not correlated with recruitment and mortality. Jatropha mollissima (Pohl) Baill. (Euphorbiaceae) and Schinopsis brasiliensis Engl. (Anacardiaceae) populations were greatly reduced and that of Mimosa ophthalmocentra Mart. ex Benth. (Mimosaceae) almost tripled, while those of most species changed little. The average annual increment in diameter wassmall (0.5mm), compared to other dry and humid forests, and it was influenced by the largenumber of plants that had decreases in the diameters of the stems or death of one or more of the branched stems. This result may be associated to the strong local seasonallity. Density was the only community variable with a statistically significant change and it had a larger influence in the small increase in basal area than the diameter increase. Monitoring for a longer period could contribute to a more complete understanding of the community dynamics.