ABSTRACT Most angiosperms rely on animals for pollination, and insects, especially bees, are being the most frequent pollinators. Many native Neotropical plants are frequently visited by the invasive honeybee (Apis mellifera), but its role in the pollination of these plants has been little investigated. We assessed the contribution of various floral visitors, including native bees and the honeybee, on the pollination of a generalist rupestrian grassland daisy, Aspilia jolyana (Asteraceae), in Serra do Cipó, Espinhaço Mountain Range, Brazil. We recorded floral visitors and measured the seed set resulting from one single visitation. We observed a total of 442 visits, mostly by bees, with Bombus pauloensis and Apis mellifera being the most common floral visitors. Other visitors included many other species of bees, flies, hummingbirds, wasps and butterflies. Pollinators significantly increased seed set in comparison to non-visited (bagged) capitula. Moreover, there was no difference among bee species/groups in their contribution to seed set. Thus, A. jolyana benefits from its generalized pollination strategy, and frequent bee visitors, including several native species and the invasive honeybee, are equally effective pollinators for this generalist daisy of rupestrian grasslands.

Bordas são áreas de transição entre dois ecossistemas e podem ter origem natural ou antrópica. A influência de borda inclui tanto os efeitos diretos, relacionados às alterações microambientais, como os efeitos indiretos que afetam as interações entre espécies. Adicionalmente, estudos sugerem que a orientação cardinal pode modificar os efeitos microambientais da borda. O objetivo deste estudo foi avaliar a influência de borda sobre os fatores microambientais, as condições edáficas locais, a densidade e a riqueza de espécies em um Cerrado sensu stricto em Itirapina, SP, Brasil. Especificamente, nós investigamos se as características microambientais (umidade relativa do ar (%), radiação fotossinteticamente ativa (PAR), temperatura e porcentagem de abertura de dossel), as condições edáficas e a composição da vegetação diferem entre parcelas (36 parcelas de 25 × 2 m distanciadas 50 m entre si) distribuídas na borda e no interior, orientadas a leste e a sul do Cerrado estudado. Todos os indivíduos lenhosos com circunferência a 30 cm da base do caule ≥ 3 cm foram amostrados e marcados. As variáveis microambientais e as amostras de solo para análises químicas e granulométricas (0-20 cm de profundidade) foram coletadas em três pontos de cada parcela. Foi registrado um total de 120 espécies distribuídas em 40 famílias. Dentre os parâmetros estruturais da vegetação, somente a densidade absoluta foi significativamente maior no interior sul do fragmento. As variáveis microambientais diferiram significativamente entre as faces leste e sul, mas não entre borda e interior. Os parâmetros microambientais e estruturais não caracterizaram uma influência da borda. Entretanto, a orientação cardinal leste e sul e fatores microambientais associados, e a presença de determinados nutrientes no solo como o Mn, influenciaram a estrutura da vegetação de Cerrado e a sua composição em espécies. Nossos resultados ressaltam a importância de considerar a orientação cardinal, além da composição de nutrientes no solo, e dos fatores microambientais, para compreender as variações da vegetação em escala local.

Edges are transition areas between two adjacent ecosystems that can be originated by natural or anthropogenic events. The edge influence includes both direct effects, related to changes on microenvironmental factors, as well as indirect effects, related to changes in species interactions. Additionally, some studies suggest that microenvironmental factors are altered by the cardinal orientation of the edge. The present study aimed to evaluate the influence of edge on microenvironmental factors, local soil conditions, woody vegetation structure, and species richness in a Cerrado sensu stricto at Itirapina, São Paulo State, Brazil. Specifically, we investigated whether microenvironmental factors (relative humidity (%), photosynthetic active radiation (PAR), temperature and percentage of canopy cover), soil conditions and vegetation composition differ among plots (36 plots of 25 × 2 m spaced 50 m apart) distributed on the edge and in the interior, facing east and south sides of the Cerrado. We sampled all woody trees and treelets with circumference ≥ 3 cm at 30 cm from its ground base within each plot. The microenvironmental variables relative humidity, PAR (photosynthetic active radiation), temperature and percent of canopy openness, and the soil samples (0-20 cm deep) for nutrients and texture analyses, were all collected at three points within each plot. We recorded a total of 120 woody species distributed among 40 plant families. Among the structural parameters of vegetation, only the absolute density was significantly higher in the interior south of the Cerrado. The microenvironmental factors were significantly different between the east and south sides, but did not differ between edge and interior. Therefore, based on the environmental and structural parameters we evaluated, there was no evidence of edge influence in the Cerrado studied. However, the east and south faces and associated microenvironmental factors, and the presence of some nutrients in the soil, such as Mn, affected the Cerrado vegetation structure and species composition. Our results highlight the importance of taking into account the cardinal orientation in addition to the soil nutrient and microenvironment parameters to better understand the factors influencing the vegetation at a local scale.