Federal University of Pernambuco

About: Federal University of Pernambuco is a education organization based out in Recife, Brazil. It is known for research contribution in the topics: Population & Context (language use). The organization has 22973 authors who have published 35124 publications receiving 426579 citations.

Phenology of caatinga species at Serra Talhada, PE, Northeastern Brazil.

Abstract: The phenology of 19 species of plants was followed for two years at Serra Talhada, Pernambuco State, Northeastern Brazil. Ten plants of each species were monitored biweekly. All plants had a complete canopy cover from February (well established rainy season) until May-June (just after rains ceased), and all but a few individuals, belonging to six species, were leafless in October-November (peak of the dry season). Leaf fall and flush, flowering, and fruiting were almost continuous in the community throughout both the years, but they peaked at different periods. The peak of leaf flush preceded the rainy season, spurred by occasional rains, followed by flowering early in the rainy season, and then fruiting. Leaf fall became more pronounced after the rainy season. The species covered a whole range of deciduousness, from those which retained their leaves throughout both years to those which were leafless during 6–7 months each year. This was mostly due to the capacity of leaf retention after the onset of the dry season. Autochoric and zoochoric species produced fruits mostly during the rainy season and anemochoric species during the dry period. The patterns of flowering and fruiting were complex. One species did not produce flowers or fruits in either year; five produced flowers and fruits in one year only and two others produced flowers in both years but fruits in only one. Most of the other species had high intraspecific synchrony and produced flowers for a shorter period than fruits. RESUMEN A fenologia de 19 especies de plantas foi acompanhada por dois anos, em Serra Talhada, PE. Dez plantas de cada especie foram observadas a intervalos de duas semanas. Todas as plantas tinham a copa completa de fevereiro (estacao chuvosa bem estabelecida) a maio—junho (logo apos o termino das chuvas) e todas, com excecao de poucos individuos pertencentes a seis especies, estavam sem foihas em outubro–novembro (auge da estacao seca). Queda e formacao de folhas novas, floracao e frutificacao foram quase continuas na comunidade, durante 0s dois anos, mas com picos em periodos diferentes. 0 pic0 de formacao de folhas precedeu a estacao chuvosa, impulsionado por chuvas esporadicas, seguido do de floracao, no inicio da estacao de chuvas, e depois pelo de frutificacao. Queda de folhas foi mais pronunciada depois do periodo chuvoso. As especies cobriram toda ma gama de caducifolia, desde as que mantiveram as folhas durante 0s dois anos as que ficaram defoliadas durante 6–7 meses cada ano. Isto deveuse, principalmente, as suas capacidades de reter folhas ao longo da estacao sea. Especies autooricas e zoocoricas produziram frutos principalmente no periodo chuvoso e as especies anemocoricas no periodo seco. Os padroes de floracao e frutificacao foram complexos. Uma especie nao produziu flores ou frutos nos dois anos, cinco produziram flores e frutos apenas em um dos anos e duas outras, em urn dos anos, produziram flores que nao se desenvolveram em frutos. A maioria das outras especies teve alta sincronia intra-especifica e produziu flores por urn periodo mais curto que frutos.

Plant β-diversity in fragmented rain forests: testing floristic homogenization and differentiation hypotheses

Abstract: Summary Land-use change is the main driver of global biodiversity loss, but its relative impact on species turnover (β-diversity) across multiple spatial scales remains unclear. Plant communities in fragmented rain forests can undergo declines (floristic homogenization) or increases (floristic differentiation) in β-diversity. We tested these alternative hypotheses analysing a large vegetation data base from a hierarchically nested sampling design (450 plots in 45 forest patches in 3 landscapes with different deforestation levels) at Los Tuxtlas rain forest, Mexico. Differences in β-diversity across spatial scales (i.e. among plots, among patches, and among landscapes) were analysed using multiplicative diversity decompositions of Hill numbers. Plant β-diversity among plots within forest patches decreased in landscapes with higher deforestation levels, leading to floristic homogenization within patches. This homogenization process can be explained by the loss of rare and shade-tolerant plant species, and the recruitment and dominance of disturbance-adapted species, and can limit the accumulation of species (γ-diversity) in landscapes with higher deforestation. Nevertheless, the landscape with the highest deforestation level showed the highest floristic differentiation among patches. This landscape showed the greatest isolation distances between patches; a landscape spatial pattern that can limit the interchange of seeds (and species) between patches. Because the study patches are undergoing secondary succession following disturbances (e.g. logging, edge effects), different disturbance regimes and increased distance among patches could lead to higher β-diversity. Synthesis. These findings indicate that patterns of floristic homogenization and differentiation depend on the landscape configuration and on the spatial scale of analysis. At the landscape scale, our results suggest that, in accordance with non-equilibrium dynamics and the landscape-divergence hypothesis, patches located in landscapes with different forest cover and different connectivity can experience contrasting successional pathways due to increasing levels of compositional differentiation between patches. These novel findings add further uncertainties to the maintenance of biodiversity in severely deforested tropical landscapes and have key ecological implications for biodiversity conservation planning.