Vegetation structure of a "Caatinga" sensu stricto (thorny deciduous woodland) was studied in a lowland area at the municipalities of Floresta and Betânia, State of Pernambuco, Brazil. Height and perimeter of all woody plants to be found in 1 hectare were censured when stem perimeter at soil level was > 3 cm and the height > 1 m. A total of 3,140 individuals belonging to 28 plant species were registered with a basal area of 18.5 m². In general, results from surveys at lowlands on plain areas presented smaller individual stem diameters than those located near streams or mountain range sites. Physiognomic differences in the caatinga sensu stricto on lowlands are related to differences on the density of plants with greater diameters. The diameter distribution of Caesalpinia gardneriana Benth. (Caesalpiniaceae) and Croton rhamnifolioides Pax & K. Hoffm. (Euphorbiaceae), the two most important tree species, indicate that these plant populations may be regenerating from former disturbance.
"Sertaneja" depression; structure; woody plants
