Phenological patterns and pollination network structure in a Venezuelan paramo: a community-scale perspective on plant-animal interactions

摘要

Background: Little information is available about life history of paramo plants such as phenology and plant-animal interactions. Aims: We analysed phenological patterns of flowering and characterised the structure of a plant-pollinator network in a Venezuelan paramo in order to identify key species in this ecosystem. Methods: We counted the number of individuals with flowers of 76 native plant species and recorded their pollinators in 16 permanent plots between 3000 and 4200 m monthly for three years. We used this dataset to develop a plant-pollinator network, on which nine different metrics related to structural properties were calculated. Results: The flowering of most species concentrated during the rainy season (between May and November), however some species have continuous flowering. The guild of floral visitors included hummingbirds, flower piercers, bumblebees, Diptera and Lepidoptera. The plant - flower visitor interaction network did not exhibit nestedness, but showed a significant specialization index (H2) and high values of functional complementarity. Conclusions: Paramo plants have the capacity of maintaining a resident nectarivorus fauna (bumblebees and hummingbirds) because of continuous flower offer during the year. However, the plant - pollinator network identified could be very sensitive to the loss component species, owing to high levels of specialisation and functional complementarity.