Vagner Santiago do Vale

An Ecological Comparison of Floristic Composition in Seasonal Semideciduous Forest in Southeast Brazil: Implications for Conservation

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. Only Copaifera langsdorffii and Hymenaea courbaril occurred 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 which Siparuna guianensis was the indicator species. This analysis revealed that similarities between studied fragments were due mainly to the successional stage of the community.

Mortality, recruitment and growth of the tree communities in three forest formations at the Panga Ecological Station over ten years (1997-2007)

ABSTRACT The area evaluated in this study was a continuous stretch comprising three vegetation formations: gallery forest, semi-deciduous seasonal forest and cerradao (woodland savanna). The aim of this study was to examine the tree community dynamics in a forest gradient—from gallery forest to cerradao —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 cerradao , 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 in creased during the period of the study, especially at cerradao . The mean mortality rate in the studied area was 2.64%.yr

Estrutura fitossociológica e grupos ecológicos em fragmento de floresta estacional semidecidual, Uberaba, Minas Gerais, Brasil

RESUMO (Estrutura fitossociologica e grupos ecologicos em fragmento de floresta estacional semidecidual, Uberaba, Minas Gerais, Brasil) Estudos em florestas estacionais semideciduais (FES) sao necessarios para caracterizar a estrutura e verificar a formacao de padroes, possibilitando tambem comparacoes de composicao floristica entre fragmentos. Este estudo foi realizado em um fragmento de FES, em Uberaba, MG, na qual foram demarcadas 25 parcelas de 20 × 20 m, amostrando-se todos os individuos arboreos vivos com circunferencia do tronco a 1,30 m do solo > 15 cm. Foram analisados os parâmetros fitossociologicos usuais e, tambem, a similaridade floristica entre a area de estudo e outras areas de FES. Foram amostrados 805 individuos, representados por 90 especies, sendo Micrandra elata (Euphorbiaceae) a especie mais importante na comunidade, seguida de Galipea jasminiflora (Rutaceae). Especies pioneiras tiveram baixa representatividade na amostra. Alem disso, a presenca de individuos de grande porte, de especies pouco comuns, associada a area basal de 45,8 m 2 ha 1 , sao evidencias de se tratar de floresta madura, em bom estado de conservacao, representativa da condicao original. A analise de similaridade entre esta e outras areas florestais remanescentes demonstrou a formacao de quatro grupos distintos, associados a regioes geograficas, com indicios de que florestas em bom estado de conservacao sao mais semelhantes entre si. Palavras-chave: distribuicao espacial, floresta mesofila, similaridade floristica.

ESTRUTURA DO ESTRATO ARBÓREO E REGENERATIVO DE UM FRAGMENTO DE FLORESTA ESTACIONAL SEMIDECIDUAL EM ITUMBIARA, GO

Semideciduous forests occur in a few places in the Cerrado biome, but are being suppressed through by agriculture and livestock in central Brazil. The objective of this study was characterize the horizontal and vertical structures, the dispersal syndromes, successional groups and floristic similarity of the tree layer and regeneration in a semideciduous forest fragment in Itumbiara, Goias state. All trees alive with circumference at breast height (CAP) ≥ 15 were identified and measured for height and diameter in 25 plots of 20 x 20 m. To the regenerative stratum the criteria was the inclusion of individuals with height ≥ 1m until CAP = 14.9 cm in 25 plots of 10 × 10 m. In both layers were sampled 100 species. The species with the highest importance in the tree layer were Nectandra megapotamica (Spreng.) Mez, and in the regenerative stratum, Siparuna guianensis Aubl. Both layers had a higher proportion of early secondary species and the zoochory dispersion syndrome was more frequent. Several important species are not represented in other semideciduous forests, and then this forest is an important permanent conservation area.

Functional leaf traits of understory species: strategies to different disturbance severities

The specific leaf area (SLA) has been related to environmental disturbances, showing a positive correlation between the disturbances intensities and SLA in a plant community. These studies, however, assessed the responses of plant community as a whole, neglecting species attributes, such as the position in the vertical stratum of forests. Considering the importance of SLA to understand forest ecological processes, this study aimed to determine the influence of the disturbance regime on the SLA of understory species, considering that, unlike for communities as a whole, an increase in the disturbance intensity implies a decrease in SLA of understory species. This study was conducted in nine understories of seasonal forests in Brazil. The most abundant species were selected and their SLA were evaluated. The variability of SLA among populations in different forests was analyzed by Students t-tests. The SLA of the understories (SLAU) was also compared by an adaptation of the Community-weighted mean index. The comparison of species SLA showed significant differences among the populations of understories under different disturbance regime, showing a decrease in SLA with an increase in the disturbance intensity. Similar results were found for the SLA of understories communities (SLAU), corroborating our hypothesis. The correlation between a reduction in species SLA and in SLA of understory with an increase in disturbance intensity, contradicted the trend observed in the literature for the community as a whole. This study highlights the importance of the evaluation of SLA in understories, as an indicator of the successional stage of communities.

Persistence of Coffea arabica and its relationship with the structure, species diversity and composition of a secondary forest in Brazil

Understanding the relationships between Coffea arabica L. and the native tree community of secondary forests regrowing after the abandonment of coffee plantations is important because, as a non-native species in the Neotropics, coffee can outcompete native species, reducing diversity and forests ecosystem services. We aimed to answer three questions: 1) Does coffee regeneration in secondary forests differ between shaded and unshaded abandoned plantations?; 2) How is coffee basal area related to structural attributes, species diversity and composition of the native community?; and 3) Do the relationships between coffee and native community differ between tree and sapling components? We sampled the tree and sapling components in a seasonal tropical dry forest that were previously used as shaded and unshaded coffee plantations. Coffee was the most important species in the sapling component of shaded systems, but was almost absent in unshaded ones. Coffee basal area was negatively related with the native density and absolute species richness of the sapling component; and was negatively related with tree density, and positively related with the percentage of pioneer individuals of the native tree component. Our results indicate that coffee persists in secondary forest communities even after more than 70 years of shaded-coffee plantations were abandoned, potentially reducing density and diversity of native species. Despite limitations, which hinder more general conclusions on coffee invasiveness in Brazilian secondary tropical forests, our results indicate that coffee is a strong competitor in the studied secondary forests and provide important insights for future research on this topic.

Shifting species and functional diversity due to abrupt changes in water availability in tropical dry forests

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.

CONSEQUÊNCIAS DA CONSTRUÇÃO DE BARRAGENS NA FLORÍSTICA, ESTRUTURA E TRAÇOS FUNCIONAIS EM FITOFISIONOMIAS DE CLIMA SAZONAL

A construcao de barragens em regioes de vale provoca o aumento na disponibilidade hidrica do solo, afetando o estabelecimento e a sobrevivencia das especies de plantas especialistas de solos com baixa umidade. Foram pesquisados artigos cientificos, documentos tecnicos e livros sobre o tema “impactos ambientais causados por usinas hidreletricas e represamentos” existentes em bases indexadoras e orgaos publicos com objetivo de evidenciar os principais impactos causados por barragens acima da cota de inundacao para florestas que antes se situavam distantes de recursos hidricos e passam a se situar proximas das aguas do lago artificial criado. Dentre os principais impactos listados pelos estudos estao: a fragmentacao de habitats, dificultando ou as vezes impossibilitando o fluxo genico entre esses fragmentos (14 estudos), alteracoes na estrutura, biomassa e fluxo de carbono (28) e modificacoes da fitofisionomia das florestas (05 estudos), sobretudo quanto a dispersao de sementes. Apesar desses impactos ja serem conhecidos, ha poucos estudos que monitoram as mudancas das funcoes desempenhadas por essas florestas a longo prazo.

Functional traits shape size-dependent growth and mortality rates of dry forest tree species

Aims: Functional traits have emerged as an important tool to evaluate plant performance. However, the environmental conditions and ecological pressures that plants face change with their size, and the relationship between traits and plant performance should therefore be size-dependent, which has rarely been tested. Methods: Here, we evaluated over a broad range of tree sizes the interspecific relationship between tree growth and mortality and eight functional stem, leaf and seed traits. We did so across 59 tree species in Brazilian dry forests and evaluated whether the relationships found for wet forest types in the literature also hold for dry forests, where water rather than light might limit tree performance. Important Findings: We indeed found a strong size-dependent relationship between demographic rates and functional traits. At small sizes, when trees are in the shaded understory, species with functional trait values that enhance light capture or shade tolerance (i.e. higher maximum adult stature, taller heights, wider crowns, higher seed mass) have higher growth and/or lower mortality rates (MR). This relationship disappears at larger sizes when trees attain better light conditions in the canopy. Drought adaptations play only a role at larger tree sizes; once trees are in the dry and exposed canopy, species with higher wood density (an indicator of cavitation resistance) have lower MRs. Our study shows that both drought and shade adaptations are important in this dry forest, and that the relationships between functional traits and plant performance changes with plant size. Plant size should therefore explicitly be included as an axis of variation in functional analyses, to better understand the relationship between functional traits and demographic rates.

Impacts of artificial reservoirs on floristic diversity and plant functional traits in dry forests after 15 years

Dams are of paramount importance to a wide variety of human services and many of their environmental problems are known; however, there are few studies in the world addressing the impacts on the native vegetation previously distant from water bodies which became close to the lakeshore created by a dam. Thus, this paper aims to analyze the responses of a dry forest to a dam after 15 years. For this, 20 random samples of 40 trees were made, 10 close to the lakeshore and 10 distant from it, by applying the central square point method. Close to the dam, we found higher values regarding basal area, number of trees, number of evergreen trees, and zoochoric syndrome, but there were lower values of Shannons diversity index. Therefore, the impacts of the dam after 15 years caused several changes to the tree community. The greater basal area close to the dam suggests that water deficit during the dry season was decreased and plants have thicker trunks. On the other hand, this sector had much more zoochoric syndrome and a larger number of evergreen trees than plots which are distant from water, suggesting changes with regard to the communitys ecological functions. Furthermore, structural floristic data shows that the sector close to the dam is less similar to other deciduous forests within the same geographical region than the sector distant from water, thus providing evidence of the impacts of dams on the tree community.