Resumo A matéria orgânica morta representa uma reserva essencial de carbono, especialmente aquela alocada na necromassa arbórea (árvores mortas em pé, serapilheira grossa e serapilheira fina), desempenhando um papel fundamental na ciclagem de nutrientes e na provisão de habitat. Entretanto, a necromassa é frequentemente desconsiderada em inventários florestais. Aqui, objetivamos realizar o primeiro levantamento de vários componentes da necromassa na Floresta Atlântica do Nordeste do Brasil, fornecendo uma base para futuros estudos integrativos relacionados à necromassa nessa região. Registramos 17 árvores mortas em pé em 0,5 hectare e 239 tocos de serapilheira grossa. As estimativas de necromassa foram 3,9 Mg.ha-1 para árvores mortas em pé, 54,24 Mg.ha-1 para serapilheira grossa e 7,2 Mg.ha-1 para serapilheira fina. Indicamos que a maior parte das árvores mortas em pé e serapilheira grossa estavam em estágios intermediários e finais de decomposição. A fração folhas foi o componente dominante da serapilheira fina e meses secos tiveram maior queda deste componente. Finalmente, destacamos que inventariar árvores mortas em pé e serapilheira grossa representa um incremento de 25,6% na biomassa arbórea acima do solo, aprimorando as informações sobre estoques de matéria orgânica em florestas úmidas. Destacamos que o compartimento de necromassa deve ser considerado em inventários florestais, também incluindo pedaços pequenos de serapilheira grossa, o que pode informar melhores práticas de manejo florestal.

Abstract Dead organic matter represents an essential reservoir of carbon, especially that allocated in standing dead trees, coarse woody debris, and fine litter, playing a pivotal role in nutrient cycling and habitat provisioning. However, necromass is frequently disregarded in forest assessments. Here, we aimed to perform the first assessment of multiple necromass compartments in the Atlantic Forest of Northeast Brazil, providing a basis for future integrative studies related to necromass in this region. We registered 17 standing dead trees in 0.5 hectare and 239 logs of coarse woody debris. Necromass had 3.9 Mg.ha-1 of standing dead trees, 54.24 Mg.ha-1 of coarse woody debris and 7.2 Mg.ha-1 of litter. We indicate that standing dead trees and coarse debris were mostly in the intermediate and final stages of decomposition. Leaves were the dominant component of litter, and drier months had more litterfall. Finally, we highlight that assessing standing dead trees and coarse woody debris adds 25.6% on top of aboveground tree mass, improving information about organic matter storage in rainforest ecosystems. Our findings emphasize that the necromass compartment must be considered in forest assessments, also including small pieces of coarse woody debris, which could inform better practices of forest management.

RESUMO As plantas lenhosas foram examinadas em uma borda formada há aproximadamente 35 anos em um fragmento de Floresta Atlântica. Foram examinados três ambientes: borda, intermediário e interior. A densidade e a área basal de árvores foram semelhantes entre os três ambientes e também próximas à de outros estudos publicados com dados da mesma região. A riqueza de espécies foi maior na borda. Sub-bosque mostrou grande riqueza de espécies no interior da floresta, mas grande diversidade e equitabilidade no ambiente intermediário. Os sub-bosques dos ambientes próximos à borda da floresta possuem mais indivíduos com diâmetros maiores que no interior, embora com densidade e área basal menores. Os resultados indicam a existência de padrões distintos para o dossel e para o sub-bosque, que provavelmente resultaram dos diferentes tempos de resposta desses dois estratos da vegetação, com o sub-bosque mostrando-se mais sensível a alterações na estrutura ambiental.

ABSTRACT The woody plants in an edge area formed approximately 35 years ago in an Atlantic Forest fragment in northeastern Brazil were examined, and three environments defined: edge, intermediate, and interior. Canopy tree densities and basal areas were found to be similar in all three environments, and also similar to previous published studies in the same region; species richness was greatest at the forest edge. The understory showed greater species richness in the forest interior, but greater diversity and equitability in the intermediate environment. Understory environments close to the forest edge demonstrated larger stem diameters than in the forest interior, although at lesser densities and with smaller total basal areas. Our results indicated the existence of distinct patterns in canopy and understory that most likely reflect differences in the response times of these two vegetation layers, with the understory being more sensitive to alterations in environmental structure.

To test the hypothesis that the physiognomy, structure and dynamics of woody species are influenced by the spatial gradient edge-interior, data were collected from these parameters in 2004, 2007 and 2010 in an Atlantic forest fragment. Species were sampled for the Canopy (DS), with circumference > 15 cm to 1.3 m soil and understory (SB) in circumference between ground level> 3 cm and CAP <15 cm on edge-gradient formed within 35 years. In 2004, we assessed three positions in the fragment: edge, intermediate and inner (> 150 m from the forest boundary), and analyzed 1,000 m² per site, divided into plots of 10 m², to measure individuals of higher class. In each plot a sub-plot of 5 m² for sampling understory was installed. Branches were collected from three adult individuals from the species to obtain the density of the wood. The number of individuals (NI), basal area (BA), mortality (TM), recruitment rate (TR), periodic annual diameter increment (IPA), loss rate (P) and gain rate (G) Area and basal turnover rates in number of individuals (TN) and basal area (TA) class tree component in the three locations showed no significant edge effect. At the edge, the understory had lower values of NI and AB and higher TM than in the forest interior. Differences between the strata occur regardless of edge sealing, since young plants present in most individuals in the sample class SB, which are more sensitive than adult trees to changes caused by the creation of the edge. Rates of loss and gain of AB and AB turnover in NI and in SB presented higher values than on the DS, which points to a stratum with larger changes. In DS there were no differences in species richness among environments differs from that observed in SB. The floristic composition of the DS in environments closer to the forest limit was quite distinct from that of the interior, indicating that there has been no recovery of floristic composition. All environments SB had low similarity. The edges of the DS and SB had a higher concentration of individuals in class intervals smaller density values timber. The DS has already recovered biomass, although the edge and intermediate environments have not recovered species composition late. The SB still suffers the edge effect. Possibly, the highest concentration of individuals is in class with lower density wood result on edge.

Com objetivo de detectar mudanças florísticas ao longo da sucessão secundária e subsidiar futuros projetos de recuperação florestal foi realizado levantamento florístico de seis áreas de floresta secundária (capoeira) de 12 e 20 anos em Pernambuco. Foram registradas 206 espécies, sendo 136 nas capoeiras de 12 anos e 161 nas de 20 anos. Fabaceae e Myrtaceae foram as famílias mais importantes, aumentando no número de espécies com a idade de regeneração. Do total de espécies, 115 foram árvores, 48 arbustos, 16 herbáceas e 24 trepadeiras, sem diferença significativa por idade de regeneração. Análise de NMDS indicou a separação dos grupos florísticos das florestas maduras e das capoeiras, assim como a formação de subgrupos de capoeiras (SF1-2-3 e SF4-5-6) com idade de regeneração distinta. A análise de similaridade ANOSIM mostrou que os grupos formados apresentaram composição florística significativamente distintas (R = 0.96) e 63% de dissimilaridade (SIMPER). Entretanto, a presença nas capoeiras de 67 espécies em comum com as florestas maduras indicam uma tendência de convergência florística. A análise de DCA do componente arbóreo e dos outros hábitos sugere que a separação dos subgrupos por idade estaria correlacionada com variáveis edáficas físicas e químicas. Todos esses resultados indicam que, numa análise de cronossequência, não apenas o tempo de abandono, mas todas as variáveis ambientais influenciam a velocidade e direção de formação da composição florística durante a sucessão secundária.

Surveys were undertaken to examine the floristic changes during secondary succession in three areas of 12 and three of 20-year-old secondary forests in Pernambuco State, Brazil. Two hundred and six species were identified, with 136 being found in the 12-year-old secondary forest and 161 species in the 20-year-old forest. Fabaceae and Myrtaceae were the most important families, increasing in species numbers with regeneration age. Of the 216 species, 115 were trees, 48 shrubs, 16 herbaceous plants, and 24 woody lianas, without significant differences between the two regeneration site ages. NMDS analysis revealed a formation of two floristic groups, distinguishing secondary and mature forests, with a further division within secondary forests in accordance with the time since abandonment. Similarity analysis ANOSIM confirmed the significance of the groups, which had floristic composition significant distinct (R=0.96) and 63% of dissimilarity (SIMPER). However, the sharing of 68 arboreal species between the secondary and mature forests suggests a floristic convergence. DCA analysis of the arboreal component as well as the other plant habits suggested that the separation of the subgroups is correlated with physical and chemical variables of the soils. All of these results indicate that, within the chronosequence analyzed, the velocity and direction of the floristic composition during secondary succession was influenced not only by the time of their abandonment, but also by a wide range of environmental variables.