Competition, environmental filtering and phylogenetic diversity in Atlantic Forests

Há ainda muitas indagações sobre os principais fatores que determinam a dinâmica e estrutura filogenética de comunidades florestais distribuídas por distintas tipologias de Floresta Atlântica, assim como também há uma escassez de estudos acerca de interações competitivas nessas florestas. Assim, este estudo foi calcado em três objetivos centrais, seguindo distintas abordagens metodológicas: a) investigar a influencia de eventos dinâmicos (mortalidade e recrutamento, ambos baseados em abundancia e biomassa) na estrutura filogenética de comunidades arbóreas da Floresta Atlântica, assim como investigar o grau de parentesco entre árvores mortas e recrutas com as sobreviventes de diferentes classes de tamanho (diâmetro); b) avaliar a distância filogenética entre três tipologias de Floresta Atlântica, distribuídas nos Estados de Minas Gerais e litoral da Bahia, e investigar a influência de fatores ambientais (clima, altitude e distância do oceano) nas suas diversidades e estruturas filogenéticas e riqueza de espécies e c) avaliar possíveis interações competitivas em diferentes tipologias de Florestas Atlânticas, relacionando densidade (medida como abundância por subparcela) e tamanho (altura e diâmetro máximos por subparcela) e medindo o grau de parentesco entre árvores mais vigorosas (maior altura e diâmetro) e as demais (sobreviventes, mortas e recrutas). Para atender aos objetivos propostos, nós amostramos por meio de subparcelas de 10 x 10 m nove florestas distribuídas pelos Estados da Bahia e Minas Gerais (sete florestas de 0.5 hectares cada uma, uma de 0.49 hectares de uma de 0.70 hectares), sendo provenientes de: Floresta de Galeria, Floresta Ombrófila e Floresta Semidecídua. Relativo ao primeiro objetivo, nossos resultados evidenciaram concomitante atuação de filtros ambientais ou eventos aleatórios e interações negativas como a competição, visto o aumento do agrupamento filogenético com a taxa de recrutamento e aumento da sobredispersão filogenética com a taxa de mortalidade, respectivamente, na montagem das comunidades florestais estudadas. Contudo, uma maior importância foi sugerida para a competição como principal interação negativa atuante, principalmente devido ao parentesco próximo entre as árvores mortas e as sobreviventes maiores que 30 cm e o maior percentual de árvores mortas observado dentre as menores que 10 cm. O segundo objetivo nos levou a resultados que indicaram um distinto gradiente ambiental (clima, altitude e distância do oceano) compreendido entre a Floresta de Galeria e Floresta Ombrófila, tendo a Floresta Semidecídua como intermediária. Estes três gradientes ambientais distintos possivelmente influenciam no parentesco distante (alto turnover filogenético) entre essas tipologias. As características ambientais particulares de cada tipologia certamente influenciaram os padrões encontrados para o conjunto total, dentre eles: a sobredispersão filogenética nos clados mais basais (MPD) com aumento da temperatura do mês mais quente e do agrupamento filogenético nesses clados com aumento da altitude e aumento da sobredispersão nos clados mais recentes (NTI) com a distância do oceano. Por fim, embasado no terceiro objetivo, nossos resultados evidenciaram fortes relações negativas entre a densidade e recrutamento em todas as tipologias, indicadas por mais altas taxas de recrutamento em parcelas com densidade mais baixa. Os traços altura máxima e diâmetro máximo apresentaram sinal filogenético, indicando seus conservantismos em linhagens evolutivas e houve baixo turnover filogenético entre as árvores mais vigorosas e as mortas.There are still many questions about the main factors ruling the dynamics and phylogenetic structure of forest communities distributed along distinct vegetation types of Atlantic Forests, as well as a scarcity of studies investigating negative interaction among plant in these forests. Thus, this study was based on three central aims following different methodological approaches: a) to investigate the influence of dynamic events (mortality and recruitment, both show in terms of abundance and biomass) on the phylogenetic structure of tree communities in the Atlantic Forest and also to figure out the relatedness among dead trees to the surviving ones from different size classes (diameter); b) to evaluate the phylogenetic distance among three vegetation types of Atlantic Forest distributed through Bahia and Minas Gerais States and to investigate the influence of environmental factors (climate, altitude and ocean distance) in their phylogenetic diversity and structure and species richness; c) to evaluate possible competitive interactions in different types of Atlantic Forests relating density (measured as abundance per subplot) and size (maximum diameter and height per subplot) and measuring the relatedness degree among the larger trees (bigger diameter and height) and the other ones (survival, dead and recruits). To achieve these aims, we sampled subplots of 10 per 10 meters in nine forests distributed along Bahia and Minas Gerais States (seven forests of 0.5 hectares each one, one of 0.49 hectares and one of 0.70 hectares) which are from: Gallery Forest, Rain Forest and Semideciduous Forest. In relation to the first aim our findings indicated simultaneous acting of environmental filters or random events and negative interactions such as competition on the assembly of the studied communities, once it was observed phylogenetic clustering increasing with recruitment rate and phylogenetic overdispersion increase with mortality rate, respectively. Nevertheless, it was suggested a higher importance to competition as main negative interaction acting as a ruler, mainly due to the close relatedness between dead trees and the survivors larger than 30 cm in diameter and the highest percentage of dead trees observed among those trees larger than 10 cm. The second aim conducted to results that indicated a distinct environmental gradient (climate, altitude and ocean distance) between Gallery and Rain Forests with the Semidecidous Forest in between representing an intermediate. These three distinct environmental gradients possibly influence in the distant relatedness (low phylogenetic turnover) among the vegetation types. The specific environmental conditions of each vegetation type certainly influenced in the patterns found for the whole subset, among them: increasing phylogenetic overdispersion in the basal clades (MPD) with temperature of the warmest month and increasing of phylogenetic clustering in these clades as the altitude was higher and overdispersion increase in the more recent clades (NTI) with increase of ocean distance. Finally, based on the third aim our findings suggested a strong negative relationship among density and recruitment in all of the three vegetation types, which were indicated by higher recruitment rates in subplots with lower density. The traits maximum diameter and maximum height showed phylogenetic signal indicating their conservatism in evolutionary lineages and there was a lower phylogenetic turnover among the larger trees and the dead ones.Fundação de Amparo à Pesquisa do Estado de Minas Gerai

Composition and phylogenetic structure of Pampean grasslands under distinct land use and presence of alien species

Alien species can modify ecosystem functions and ecological processes in natural communities and potentially become inva- sive. In the Brazilian Pampean grasslands, reports of changes in land use and invasions of alien plant species are becoming more frequent. This study aimed to investigate species composition and phylogenetic relationships between native and alien plants across four sites of Brazilian Pampean grasslands under distinct land uses (NOM: no agricultural management; GRZ: grazed pastures; AGR: agrarian crops; ROAD: roadside). The phylogenetic relationship between native and alien species was analyzed at two scales: inter-site and intra-site. We found phylogenetic diversity dissimilarity across all sites consider- ing all species. Overall, across all sites, we found random phylogenetic relationships among alien and native species. We found significant phylogenetic clustering in the most disturbed site (ROAD) for the two sets of species: all (alien and natives) and only native species. We conclude that clustering of phylogenetic relationships among alien and native species is only evident at small (intra-site) sampling scales in environments subject to high levels of disturbance (i.e., roadsides) in the studied Pampean Grasslands, suggesting that environmental filtering plays an important role in local community assembly

Species composition, community and population dynamics of two gallery forests from the Brazilian Cerrado domain

Figure 1 - Localization of study site

Improved retrieval of phylogenetic signals from normalized foliar reflectance spectra in Neotropical forest gaps

Distinct data pre-processing techniques affect features derived from spectral data, such as the occurrence of phylogenetic signals in the foliar spectra. This study investigates how untransformed and transformed foliar spectral data affect the phylogenetic signal of 53 woody plant species located in regenerating forest gaps. The spectral signature for each species was considered under untransformed (raw reflectance spectra) and transformed (normalization by first derivative) aver- age of reflected wavelengths from four spectral regions: VIS (visible region: 400–700 nm), NIR (near-infrared region: 701–1349 nm), SWIR-1 (short-wave infrared region part one: 1350–1850 nm), and SWIR-2 (short-wave infrared region part two: 1851–2450). We evaluated the evolutionary conservation (phylogenetic signal) through Blomberg (K) and Pagel (λ) metrics for all 2051 averaged (untransformed and transformed) reflected wavelengths of the species. We found a predomi- nant evolutionary convergence of wavelengths in both transformed and untransformed foliar spectra. Specifically, we found significant phylogenetic signal for transformed spectra in NIR and SWIR-1 regions and reduced portions in SWIR-2. For the untransformed spectra, the significant phylogenetic signals in SWIR-2 stand out. In conclusion, such main results indicate that normalization by first derivative performs better in disentangling overlapping wavelengths. Thus, we recommend to perform phylogenetic analysis on the transformed spectra since it can highlight the phylogenetic signal of plant features that otherwise are underemphasized in untransformed foliar spectra

Long-term monitoring of diversity and structure of two stands of an Atlantic Tropical Forest

This study aimed to report the long-term monitoring of diversity and structure of the tree community in a protected semideciduous Atlantic Forest in the South of Minas Gerais State, Southeast Brazil. The study was conducted in two stands (B and C), each with 26 and 38 10 m x 30 m plots. Censuses of stand B were conducted in 2000, 2005 and 2011, and stand C in 2001, 2006 and 2011. In both stands, the most abundant and important species for biomass accumulation over the inventories were trees larger than 20 cm of diameter, which characterize advanced successional stage within the forest. The two surveyed stands within the studied forest presented differences in structure, diversity and species richness over the time