Weather Variables Affecting the Behaviour of Insect Flower Visitors and Main Pollinators of Erythroxylum myrsinites Martius (Erythroxylaceae)

Basic research assessing environmental effects on entire pollinator communities are still uncommon, particularly for rare and commercially unattractive plant-pollinator partners. We investigated the community of flower visitors of Erythroxylum myrsinites to check for potential pollinators and to check the extent of weather influence of visitor behaviour, registered as the number of visitors attending flowers of E. myrsinites. We then calculated species’ dominance and constancy and assessed location of pollen attachment in each visitor’s body. We correlated weather variables with the composition and abundance of visits carried out by the entire community and by most constant and dominant species. The wasps Polybia sericea, P. ignobilis and P. fastidiosuscula showed the highest values of constancy, dominance and attached pollen. There was a community-level effect of atmospheric pressure, solar radiation and wind speed on the number of visits. Atmospheric pressure affected the number of visits of eudominant species P. fastidiosuscula and P. sericea, while solar radiation affected the number of visits of P. ignobilis. Our results demonstrate the influence of weather variables on flower visiting insects and suggest the importance of native wasps in pollen transport and pollination, a relationship that should be further studied under the worldwide bee pollination decline

The influence of fire and cattle grazing on Araucaria population structure in forest-grasslands mosaics

Artigo mostrando a importância do manejo com fogo e gado para a expansão das áreas com araucarias na Serra de Santa Catarina. Pesquisa realizada no âmbito do projeto PELD-BISC.Disturbances caused by land management via fire and cattle grazing can alter the population structure of keystone species that change the output of vegetation dynamics. Adult araucaria trees (Araucaria angustifolia) can facilitate the establishment of other woody plants and, thus, influence the expansion of forests over grasslands in the highlands of southern Brazil. Here we aimed to check araucaria population structure under two types of management – with or without fire and grazing– and in three habitat types: forests, shrublands and grasslands. We sampled araucaria populations in 40 transects (100×4 m), half of each located in the forest, and the other half, in variable extensions of shrublands or grasslands. Of the 40 transects, 18 were under management with fire and grazing and 22 in a protected area where the two disturbances are prevented (S ̃ ao Joaquim National Park). Overall, we sampled 339 araucaria seedlings, 59 saplings, 44 juveniles and 128 adults. Population structure differed both among habitats, between types of management, and between the same habitats but under distinct types of management. Population density was 1.4 times higher in areas with fire and grazing than without such disturbances, which was caused mostly by a larger number of seedlings. Under fire and grazing, we found 1.4 times more adults in forests, 5.7 times more seedlings in shrublands and 5.3 times more seedlings in the grassland than in the same habitat but without disturbances. Our results indicate that araucarias reach and germinate under all conditions but rarely surpass the seedling stage in grasslands and shrublands where fire and grazing is used. Consequently, fire and grazing disturbances should slow down forest expansion over shrublands and grasslands. In contrast, when disturbances are barred, araucarias can grow large enough to trigger their facili- tative effect and then gear up the pace of forest expansion.CNPq/Capes/FAPs/BC-Fundo Newton/PELD no 15/2016 and FAPESC/2018TR0928

Fenologia de espécies arbóreas em uma floresta ribeirinha em Santa Maria, sul do Brasil

Os eventos fenológicos estão geralmente sujeitos a variações ocorrentes no ambiente, especialmente relacionados ao clima. O objetivo do presente estudo é descrever a atividade fenológica do componente arbóreo em uma floresta ribeirinha subtropical, relacionando os padrões vegetativos e reprodutivos com variáveis climáticas. Vinte e três espécies pertencentes a 15 famílias botânicas foram observadas quanto à floração, frutificação, presença de folhas jovens, folhas maduras, queda foliar e brotamento. Todas as espécies apresentaram fenofases sazonais e mostraram associação com a variação do fotoperíodo e temperatura. O pico de floração transcorreu durante o mês de novembro, sendo a frutificação, mais intensa no decorrer dos meses seguintes, embora frutos maduros zoocóricos estivessem disponíveis durante todo o ano. A queda foliar correlacionou-se com a diminuição do fotoperíodo e temperatura, atingindo maior intensidade durante agosto e setembro. As espécies de comportamento decíduo ocorreram predominantemente como espécies emergentes, enquanto que as demais ocuparam as demais posições verticais. O desencadeamento das fenofases esteve diretamente relacionado às variações sazonais de fotoperíodo e temperatura, enquanto que a ausência de períodos sistematicamente secos demonstra que as espécies não apresentam restrição hídrica regular

Interaction of land management and araucaria trees in the maintenance of landscape diversity in the highlands of southern Brazil.

In the southern Brazilian highlands, pre-Columbian societies created domesticated landscapes through the use and management of forests, including nurse Araucaria angustifolia trees, a common conifer in these regions. Nowadays, local smallholders still use traditional practices, such as burning, to promote vegetation for cattle grazing in highland grasslands. Even though burning is normally of small extent and low frequency, such management can slow down natural forest expansion and contribute to the maintenance of grasslands, by opposing the facilitative effect of nurse araucaria trees. To comprehend the interplay between human cultural management, species interactions and the environment, it is important to better understand how these relations affect diversity and composition. Our goal was to investigate how land management, biotic interactions and abiotic factors affect saplings species richness, abundance and composition. We hypothesized that (1) land management would decrease sapling richness and abundance and change sapling composition, (2) nurse araucaria trees would increase species richness and abundance and change sapling composition, and (3) the interactive effect between land management and nurse araucaria trees would shape sapling richness, abundance and composition. Data were collected in unmanaged and managed conditions, both beneath araucaria crowns and in nearby treeless areas. Our results indicate that abundance and species composition are affected by land management and araucaria crown influence. The highest values of sapling abundance were found beneath crowns in unmanaged areas. Species composition changed between all assessed combinations of land management and crown influence. Our study demonstrates the major roles of land management and facilitation in structuring communities, despite the effects of rock and grass cover. Moreover, our results clarify patterns and processes that may emerge in natural highland grasslands, such as the conversion of grasslands into forests and the loss of cultural landscapes when the main local management actions are excluded