ABSTRACT Dry tropical forests are a key component in the global carbon cycle and their biomass estimates depend almost exclusively of fitted equations for multi-species or individual species data. Therefore, a systematic evaluation of statistical models through validation of estimates of aboveground biomass stocks is justifiable. In this study was analyzed the capacity of generic and specific equations obtained from different locations in Mexico and Brazil, to estimate aboveground biomass at multi-species levels and for four different species. Generic equations developed in Mexico and Brazil performed better in estimating tree biomass for multi-species data. For Poincianella bracteosa and Mimosa ophthalmocentra, only the Sampaio and Silva (2005) generic equation was the most recommended. These equations indicate lower tendency and lower bias, and biomass estimates for these equations are similar. For the species Mimosa tenuiflora, Aspidosperma pyrifolium and for the genus Croton the specific regional equations are more recommended, although the generic equation of Sampaio and Silva (2005) is not discarded for biomass estimates. Models considering gender, families, successional groups, climatic variables and wood specific gravity should be adjusted, tested and the resulting equations should be validated at both local and regional levels as well as on the scales of tropics with dry forest dominance.

Avaliou-se, neste trabalho, a estrutura de um fragmento florestal antropizado denominado Mata das Galinhas, Engenho Humaitá, Catende, Pernambuco, e se utilizaram, para avaliar a composição florística e a estrutura fitossociológica, 14 parcelas de 10 x 25 m a fim de amostrar os indivíduos arbóreos com circunferência a 1,30 m do solo (CAP) ≥ 10 cm. Foram estimados, então, densidade, frequência e dominância e valor de importância (VI) e o índice de Shannon, além de registrados 438 indivíduos pertencentes a 63 espécies, 45 gêneros e 29 famílias. As famílias de maior importância foram Mimosaceae, Moraceae, Anacardiaceae e Lecythidaceae e as espécies com maiores valores de VI, foram Brosimum discolor, Parkia pendula, Eschweilera ovata, Thyrsodium spruceanum, Tapirira guianensis, Protium heptaphyllum, Casearia arborea, Helicostylis tomentosa, Dialium guianense, Schefflera morototoni, Himatanthus phagedaenicus e Cupania racemosa. Quando observado isoladamente, conclui-se que o fragmento estudado possui pouca relevância; entretanto, se considerado conjuntamente com outros fragmentos da área, sua diversidade é significativa o que justificaria esforços para sua conservação e manejo.

The structure of a forest fragment, known as "Mata das Galinhas" at Humaitá sugar mill, Catende, Pernambuco, Brazil was evaluated. To evaluate the floristic composition and the phytosociological structure under anthropic action 14 plots of 10 x 25 m were used to sample the arboreal individuals with circumference at breast height (CBH) ≥ 10 cm. The density, frequency, and dominance, the importance value (IV) and the Shannon's index were calculated. A total of 438 individuals distributed into 63 species, 45 genera and 29 families were recorded. The families of larger importance in the study were Mimosaceae, Moraceae, Anacardiaceae and Lecythidaceae. The species with larger values of IV were Brosimum discolor, Parkia pendula, Eschweilera ovata, Thyrsodium spruceanum, Tapirira guianensis, Protium heptaphyllum, Casearia arborea, Helicostylis tomentosa, Dialium guianense, Schefflera morototoni, Himatanthus phagedaenicus and Cupania racemosa. When observed separately, the studied fragment possesses low relevance; however, when considered jointly with other fragments of the area, its diversity is significant, justifying efforts for conservation and management.