Direct and cascading effects of landscape structure on tropical forest and non-forest frugivorous birds.

Global biodiversity is increasingly threatened by land-use change, but the direct and indirect drivers of species diversity in human-modified tropical landscapes are poorly known. Forest-dependent species are expected to be particularly sensitive to changes in landscape composition (e.g., forest loss) and configuration (e.g., increase of forest edges), both directly and indirectly through cascading landscape effects on local patterns of forest structure and resource availability. In contrast, non-forest-dependent species are probably more strongly related to landscape changes than to local forest patterns, as these species are able to use resources not only from the forest, but also from other landscape elements over larger spatial scales. We tested these hypotheses using structural equation modeling. In particular, we sampled 20 landscapes (115 ha each) from the Brazilian Atlantic rainforest to assess the effect of landscape-scale forest cover and amount of forest edges on the diversity of frugivorous birds, both directly and indirectly through the effect that these landscape variables may have on vegetation complexity and fruit biomass. We separately assessed the response of forest-dependent and non-forest-dependent frugivores to infer potential mechanisms underlying bird assemblages in fragmented landscapes. The diversity of forest-dependent birds mainly decreased with the simplification of vegetation complexity in more deforested landscapes, but increased with increasing fruit biomass in more forested landscapes (indirect effects). Both patterns were significant, thus supporting a strong bottom-up control, i.e., local habitat simplification and resource scarcity in highly deforested landscapes limits the maintenance of forest-dependent birds. Conversely, but as expected, non-forest-dependent birds were more strongly and directly related to landscape-scale patterns. In particular, landscapes with higher forest edge amount showed higher bird species diversity, probably because the increasing length of ecotones and interspersion/juxtaposition of different habitat types in landscapes with more forest edges can increase resource availability and foraging efficiency of non-forest-dependent birds. As the seed dispersal services offered by forest-dependent species cannot be ecologically compensated for by the proliferation of non-forest-dependent species, preventing forest loss is imperative to maintain forest-dependent birds and forest regeneration in this vanishing biodiversity hotspot.

Reproductive phenology of Miconia mirabilis (Melastomataceae) within three distinct physiognomies of Atlantic Forest, Bahia, Brazil / Fenologia reprodutiva de Miconia mirabilis (Melastomataceae) em três fisionomias distintas na Floresta Atlântica, Bahia, Brasil

Although Miconia mirabilis is a very common species in disturbed forest areas and is known for providing food resources for the local fauna, little is known about its reproductive phenology and other ecological aspects. The present study compares intra- and inter-annual patterns in the reproductive phenophases of that species in three distinct physiognomies of Atlantic Forest in Southeastern Bahia based on semi-quantitative observations conducted over a period of three years. We searched for possiblerelationships with climatic variables, differences among sites and synchrony. Both the flowering and fruiting strategies of M. mirabilis were classified as annual extended in all three study sites. We found no significant differences among years. Despite low seasonality of the regional climate, intensities of the different phenophases were negatively correlated with day length and temperature. In general, inter- and intra-population synchrony for flowering and fruiting was high (between 0.65 and 0.78), except for inundated forest, probably due to the stress caused by flooding. Given that Miconia mirabilis has the potential to be an important food resource for the local fauna due to the large quantities of flowers and fruits produced and their almost year-round availability, and its capacity for occupying impoverished areas, the species may be considered in restoration programs as a potentially interesting species capable of attracting frugivores to disturbed areas.

Apesar de Miconia mirabilis ser uma espécie comum em áreas de floresta perturbada e conhecida por fornecer recursos alimentares para a fauna local, pouco se sabe sobre sua fenologia reprodutiva e outros aspectos ecológicos. O presente estudo teve como objetivo comparar os padrões intra e interanual das fenofases reprodutivas da espécie em três fisionomias distintas de Floresta Atlântica no sudeste da Bahia com base em observações semi-quantitativas, realizadas num período de três anos. Também procurou por possíveis relações com as variáveis climáticas, diferenças entre os locais e sincronia. Ambas as estratégias, floração e frutificação, de M. mirabilis foram classificadas como anuais estendidas em todos os três locais de estudo. Não houve diferenças significativas entre os anos. Apesar do clima regional apresentar baixa sazonalidade, as intensidades das diferentes fenofases foram negativamente correlacionadas com o comprimento do dia e temperatura. Em geral, a sincronia inter e intra populacional para a floração e frutificação foi alta (entre 0,65 e 0,78), exceto para a floresta inundada, provavelmente devido ao estresse causado pelo solo alagado. Assim, Miconia mirabilis tem potencial de ser um importante recurso alimentar para a fauna local, devido a grande quantidade de flores e frutos produzidos, sua disponibilidade quase o ano todo, e por ocupar áreas empobrecidas, a espécie pode ser considerada potencialmente interessante em programas de restauração e capaz de atrair animais frugívoros em áreas perturbadas.