Abstract The highly biodiverse Atlantic Forest has been heavily exploited and its remnant areas, which are mostly composed of secondary forests, cover less than 20% of its original extension. This study analyzed the structure, aboveground biomass (AGB) and species diversity of a secondary evergreen rainforest in the state of Santa Catarina, southern Brazil. Individuals with diameter at breast height ≥ 5 cm on 22 sample plots were measured, totalizing 3.49 hectares of sampled area. A mean AGB of 201.6 Mg ha-1 (standard deviation = 35.5) was found; Hyeronima alchorneoides and Miconia cinnamomifolia represented 29.1% and 7.6% of the community AGB ha-1, respectively. A total of 153 species distributed in 107 genera and 55 families was observed; it was estimated that 121 species (95% confidence interval: [117, 125]) occurred in one hectare. These results highlight the importance of secondary forests for biodiversity restoration/conservation and carbon sequestration.

Abstract The majority of Atlantic Forest fragments in Southern Brazil are second-growth forests dominated by fast-growing species with considerable market-value timber. Nevertheless, volume prediction models are scarce, especially to estimate tree total volume (i.e., stem plus branches). This study approached the issue through the following aims: to fit and select stem and total volume models (generic and species-specific) using data from 288 harvested trees in a management operation, and to fit generic and species-specific bark factors. The power model embedding diameter at breast height (D) and tree stem or total height (H) presented the greatest prediction strength for both stem and total tree volume. Models including only D to predict total tree volume were similar to double-entry models regarding goodness-of-fit. Therefore, they may be useful in the context of subtropical closed-canopy forests, where the difficulty and uncertainty in H measurements are not trivial. Species-specific models fitted for Miconia cinnamomifolia (DC) Naudin. and Hyeronima alchorneoides Allemão surpassed generic models only for the former species. Nevertheless, the prediction improvement should offset the eventual extra efforts implied in the collection of reliable samples of these species. Finally, bark factors stood as a satisfactory tool for inside bark mean volume estimation.

RESUMO As florestas secundárias, predominantes em Santa Catarina, apresentam alto potencial para produção sustentável de madeira, entretanto faltam informações para estimar sua produtividade. Este estudo teve o objetivo de gerar equações de volumes de fuste e total (incluindo galhos), além dos fatores de forma e de casca, para florestas secundárias da Floresta Ombrófila Densa do Estado. Foram cubadas 187 árvores pelo método de Smalian e testados seis modelos volumétricos, utilizando-se análise de regressão, todos com resultados satisfatórios, destacando-se o de Schumacher-Hall (linearizado). As equações recomendadas para estimar o volume total com e sem casca são, respectivamente, ln(vt) = - 10,045586 + 2,349493*ln(dap) + 0,640598*ln(ht) e ln(vt) = - 10,206982 + 2,348857*ln(dap) + 0,634736*ln(ht), e para os volumes do fuste com e sem casca, respectivamente, ln(vf) = - 9,285656 + 2,100113*ln(dap) + 0,665269*ln(hf) e ln(vf) = - 9,504432+ 2,140098*ln(dap) + 0,637631*ln(hf). O fator de forma normal estimado é 0,8027, enquanto o fator de casca é 0,9301.

ABSTRACT Secondary forests prevalent is Santa Catarina State present high potential for sustainable production of timber. However, we lack information to estimate their productivity. This study aimed at generating equations to estimate the stem volume and total volume (including branches), in addition to the form and bark factors, for secondary forests of the Atlantic rainforest in the State. We scaled 187 trees by Smalian method and tested six volumetric models through regression analysis, all with satisfactory results, notably the Schumacher-hall (linearized). The recommended equations to estimate the total volume with and without bark are, respectively, ln(vt) = -10.045586 + 2.349493*ln(dap) + 0.640598*ln(ht) and ln(vt) = -10.206982 + 2.348857*ln(dap) + 0.634736*ln(ht), and to estimate the stem volume with and without bark, respectively, ln(vf) = -9.285656 + 2.100113*ln(dap) + 0.665269*ln(hf) and ln(vf) = -9,504432 + 2.140098*ln(dap) + 0.637631*ln(hf). The estimated form factor is 0.8027, while the bark factor is 0.9301.