Temporal variation of pollination classes in a tropical Venezuelan plain: the importance of habitats and life forms

Abstract

Pollination of a total of 155 plant species was evaluated monthly in relation to flowering phenology, habitats, and life forms in the Venezuelan Central Plain. The relationships between flowering phenology and pollinating agent classes and their abundance were evaluated. The total number of pollinating agent classes was significantly correlated with the number of plant species for habitats and life forms, and at the community level. The number of pollinating agent classes did not change statistically with respect to flowering phenology for life form, habitats, and overall community, but the number of pollinting agent classes increased from the dry season to the rainy season for overall community and habitats, except for forest. The abundance of pollinating agents was significantly affected by flowering time. A cluster analysis revealed that the abundance of pollinating agent classes differed throughout the year, separating the dry and rainy seasons. Two trends were found in the temporal pattern of the nine pollinating agents: (1) nonseasonal, in which flowering of bat- and bird-pollinated species did not change drastically throughout the year; and (2) seasonal, in which the number of bee-, butterfly-, fly-, wasp-, moth-, beetle-, and wind-pollinated species changed throughout the year, increasing from the dry to the rainy season at the community level. The number of pollinating bees, butterflies, flies, and wasps peaked during the dry season for trees and shrubs, and therefore for forest. The number of moth-pollinated species increased from the mid-dry season to the rainy season, with a peak during the dry–rainy transition period. Beetle- and wind-pollinated species are phenologically concentrated in the rainy season: beetle-pollinated species were mainly in the forest and forest–savanna transition, and wind-pollinated species were associated with herbaceous species in savanna and disturbed areas. The distribution of pollinating agents was affected by seasonality in habitats and life forms. Therefore, life form may be considered a proximate element, reducing interference in the pollination process at the community level.