1. Forests account for a substantial part of the terrestrial biomass storage and productivity. To better understand forest productivity, we need to disentangle the processes underlying net biomass change. 2. We tested how above-ground net biomass change and its underlying biomass dynamics (biomass recruitment, growth and mortality) can be explained by four alternative and contested hypotheses; the soil fertility, biomass ratio, niche complementarity and vegetation quantity hypotheses. 3. Above-ground biomass dynamics were evaluated over a 5-year period in 200 permanent sample plots in 8 tropical dry forests in Brazil, and related to soil fertility, community-weighted mean (CWM) traits that are important for carbon storage and sequestration (wood density, specific leaf area, maximum stem diameter and deciduousness), species richness, functional diversity and initial stand biomass. 4. Initial stand biomass was the best predictor of all three processes of biomass dynamics, providing strong support for the vegetation quantity hypothesis. In these dry forests, the dominance of conservative species, rather than of acquisitive species, is associated with high biomass growth and storage, probably because their low specific leaf area and high wood density allow them to keep on functioning during drought stress. 5. Paradoxically, high soil fertility (Ca) led to low biomass productivity, probably because of nutrient imbalance. 6. In contrast to what is shown for controlled experiments, we found no support for niche complementarity (in terms of functional diversity or species richness) for forest productivity. Biomass storage was favoured by low-rather than high trait diversity, as most of the biomass is concentrated in species with large stem diameter and high wood density. 7. Synthesis. Biomass dynamics are mainly shaped by vegetation quantity, and then by vegetation quality, in line with the mass ratio hypothesis. Dry forests show different trait-productivity relationships than wet forests, as stands with 'slow' trait values are 'fast' in terms of productivity. Diversity matters, but in a different way than expected; high trait diversity does not enhance productivity, but instead, does low trait diversity enhance carbon storage.

We examined floristic patterns of ten seasonal semideciduous forest sites in southeastern Brazil and conducted a central sampling of one hectare for each site, where we took samples and identified all individual living trees with DBH (diameter at breast height, 1.30 m) ≥4.8 cm. Arboreal flora totaled 242 species, 163 genera, and 58 families. Fabaceae (38 species) and Myrtaceae (20 species) were families with the largest number of species. OnlyCopaifera langsdorffiiandHymenaea courbariloccurred at all sites. Multivariate analysis (detrended correspondence analysis and cluster analysis) using two-way indicator species analysis (TWINSPAN) indicated the formation of a group containing seven fragments in whichSiparuna guianensiswas the indicator species. This analysis revealed that similarities between studied fragments were due mainly to the successional stage of the community.

Considerando que o regime de queima é um dos principais fatores que alteram a estrutura e composição de espécies de uma comunidade vegetal, este trabalho teve como objetivo analisar o efeito do fogo na composição florística e estrutura da vegetação lenhosa de Cerrado sentido restrito no Parque Estadual da Serra de Caldas Novas (PESCAN), Goiás, submetida a diferentes regimes de queima. Foram utilizadas duas áreas de Cerrado sentido restrito: uma delas submetida ao fogo em 2002 e 2006 e outra sem a passagem do fogo nessas duas épocas. Em cada área foram estabelecidas 25 parcelas de 20 x 20 m, sendo incluídas no estudo todas as árvores (C30>15 cm). As duas áreas estudadas apresentaram composição florística similar, evidenciada pelo Coeficiente de Sorensen, o qual encontrou 84% de similaridade na composição florística entre as áreas. Entretanto, a estrutura da vegetação apresentou diferenças relevantes, evidenciada pelo Indice de Similaridade de Bray Curtis, o qual obteve valor de 0,67, que foi refletido por mudanças na estrutura das comunidades estudadas. A área queimada apresentou menor número de indivíduos, de espécies, menor valor de área basal e, por conseguinte, do Índice de Diversidade de Shannon (H') e Equabilidade (J'). Nesse sentido, provavelmente a frequência das queimadas ocorridas na área não foram suficientes para evidenciar o efeito do fogo no processo de alteração na composição das espécies lenhosas. Entretanto, o fogo exerceu papel relevante na modificação da estrutura da vegetação.

Resumo Estudos fenológicos auxiliam na compreensão do comportamento das espécies em resposta a alterações no ambiente e são também importantes para a conservação e manejo das mesmas. A fenologia de Paratecoma peroba (Record & Mell) Kuhlm. foi estudada no período de outubro/2005 a dezembro/2007 na Mata do Carvão (Estação Ecológica Estadual de Guaxindiba), São Francisco do Itabapoana, RJ. As observações foram realizadas mensalmente, exceto durante a fase de floração que ocorreram em intervalos quinzenais. Acompanharam-se 42 indivíduos que apresentaram comportamento fenológico sazonal, com a senescência foliar ocorrendo no início da estação seca e a queda foliar entre meados e final desta mesma estação. O brotamento de novas folhas ocorreu no início da estação chuvosa. As percentagens de Fournier encontradas para as fenofases reprodutivas foram baixas e somente indivíduos com DAP > 16 cm apresentaram botões florais. No final da estação seca de 2005, os indivíduos apresentaram fenofases reprodutivas, com a floração ocorrendo na transição da estação seca para chuvosa e a frutificação foi longa (cerca de um ano) tendo início na estação chuvosa (novembro), com os frutos dispersando as sementes aladas no início da estação chuvosa seguinte. Nos anos seguintes, 2006 a 2008, não foi observado evento de floração. A espécie foi caracterizada como decídua, apresentando periodicidade de floração supra-anual. Palavras chave: brotamento, botões florais, fenologia, Mata atlântica, senescência. Abstract Phenological studies help the understanding of species behavior as a result to environmental changes and are also important for species conservation and management. The phenology of Paratecoma peroba (Record & Mell) Kuhlm. was studied from October/2005 to December/2007 in Mata do Carvão (Guaxindiba Ecological Station), São Francisco do Itabapoana, RJ. The observations were done in one-month intervals, except the flowering that was done at two week intervals. Forty two individuals were systematically observed. They showed phenological pattern characterized by the seasonal occurrence of the phenophases, with leaf senescence occurring at the beginning of the dry season and the leaf fall between the middle and the end of this season. New leaves were flushed at the beginning of the wet season. Fournier intensity values were low for reproductive phenophases and only trees with diameter at breast height (dbh) > 16 cm sprouted flowers. Reproductive phenophases started at the end of dry season of 2005, with flowering occurring in the transition of the dry to the wet season. Fruiting was long (one year), starting at the beginning of the wet season (November) with dispersion of the anemocoric seeds occurring at the beginning of the following wet season. However, in the following years (2006-2008), flowering did not occur. This species was classified as deciduous, with a supra-annual flowering period.

No abstract

Recent insights show that tropical forests are shifting in species composition, possibly due to changing environmental conditions. However, we still poorly understand the forest response to different environmental change drivers, which limits our ability to predict the future of tropical forests. Although some studies have evaluated drought effects on tree communities, we know little about the influence of increased water availability. Here, we evaluated how an increase in water availability caused by an artificial reservoir affected temporal changes in forest structure, species and functional diversity, and community‐weighted mean traits. Furthermore, we evaluated how demographical groups (recruits, survivors and trees that died) contributed to these temporal changes in tropical dry forests. We present data for the dynamics of forest change over a 10‐year period for 120 permanent plots that were far from the water’s edge before reservoir construction and are now close to the water’s edge (0–60 m). Plots close to the water’s edge had an abrupt increase in water availability, while distant plots did not. Plots close to the water’s edge showed an increase in species and functional diversity, and in the abundance of species with traits associated with low drought resistance (i.e., evergreen species with simple leaves and low wood density), whereas plots far from the water’s edge did not change. Changes in overall community metrics were mainly due to recruits rather than to survivors or dead trees. Overall stand basal area did not change because growth and recruitment were balanced by mortality. Synthesis. Our results showed that tropical dry forests can respond quickly to abrupt changes in environmental conditions. Temporal changes in vegetation metrics due to increased water availability were mainly attributed to recruits, suggesting that these effects are lasting and may become stronger over time. The lack of increase in basal area towards the water’s edge, and the shift towards higher abundance of soft‐wooded species, could reduce the carbon stored and increase the forest’s vulnerability to extreme weather events. Further “accidental” large‐scale field experiments like ours could provide more insights into forest responses and resilience to global change.

The area evaluated in this study was a continuous stretch comprising three vegetation formations: gallery forest, semideciduous seasonal forest and cerradão (woodland savanna). The aim of this study was to examine the tree community dynamics in a forest gradient-from gallery forest to cerradão-at Panga Ecological Station, in the city of Uberlandia, located in the state of Minas Gerais, Brazil. The study was based on data from a previous inventory of the continuous forest conducted in 211 permanent 10 × 10 m sample plots in eight parallel transect running perpendicular to Panga Creek. Trees with a diameter at breast height ≥ 4.77 cm were sampled in 1997, 2002 and 2007. With the exception of the cerradão, there was a net reduction in tree density over the studied period of ten years, because mortality rates were higher than the recruitment rates. The basal area increased during the period of the study, especially at cerradão. The mean mortality rate in the studied area was 2.64%.yr , respectively. In general, mortality rates and recruitment rates have increased during the two successive periods of measurement and showed an imbalance in favor of mortality for the semideciduous seasonal forest and the gallery forest. This fact, added to the low density and high basal area, suggest that there was a process of thinning in the tree community. However, at cerradão, there was an imbalance in favor of recruitment, with a consequent increase in density and basal area, indicating that the cerradão is in a construction phase, which was further favored by a decrease in the occurrence of fire and other anthropogenic disturbances. When the turnover rates are taken into consideration, the global dynamics of the study area over the ten years evaluated can be expressed as cerradão > semideciduous seasonal forest > gallery forest.

As Florestas Estacionais Semideciduais ocorrem em alguns locais no Bioma Cerrado, mas estão sendo suprimidas em meio à ampla matriz agropecuária no Brasil Central. O objetivo do trabalho foi caracterizar a estrutura horizontal e vertical, as síndromes de dispersão, os grupos sucessionais e a similaridade florística do estrato arbóreo e regenerativo de um trecho de fragmento de Floresta Estacional Semidecidual no município de Itumbiara, GO. Todos os indivíduos arbóreos vivos com circunferência do tronco a altura do peito (CAP) ≥15 foram identificados e medidos quanto à altura e circunferência do tronco em 25 parcelas de 20 x 20 m. A amostragem do estrato regenerativo foi realizada em 25 subparcelas de 10 m x 10 m, totalizando 0,25 ha, alocadas no vértice inferior direito das parcelas utilizadas para a amostragem do estrato arbóreo. Nestas subparcelas foram identificados e contados todos os indivíduos regenerantes de espécies arbóreas com altura maior ou igual a 1 m até aqueles com CAP < 15 cm. Para o estrato arbóreo foi calculados: a densidade, frequência, dominância, valor de importância e a estratificação vertical. Nos dois estratos foram amostradas 100 espécies. A espécie com maior valor de importância no estrato arbóreo foi Nectandra megapotamica (Spreng) Mez, e no estrato regenerativo Siparuna guianensis Aubl teve maior número de indivíduos. Ambos os estratos apresentaram maior proporção de espécies secundárias iniciais e a zoocoria foi a síndrome de dispersão mais frequente. A estrutura fitossociológica atual mostra que o fragmento contém diversas espécies pouco representadas em outras Florestas Semideciduais, o que mostra a sua importância como área de preservação permanente. Palavras-chave: estratificação; grupos ecológicos; síndrome de dispersão.