Pollen on stigmas of herbarium specimens: A window into the impacts of a century of environmental disturbance on pollen transfer

Abstract

Pollination is necessary for plant reproduction but often highly susceptible to disruption, for example, by habitat fragmentation and climate change. Here, we indirectly evaluated on a century timescale pollination interactions for species in one of the historically most disturbed habitats on earth—tropical dry forests of Hawaiʻi. We employed a novel method for acquiring a historical perspective on temporal change in pollination by characterizing pollen on stigmas of herbarium specimens from six remnant native species collected from 1909–2002. We determine whether temporal shifts occurred in (1) pollination quantity and quality or (2) the composition of species interacting via pollen transfer. While pollen quantity remained constant, these remnant species interact with different species in modern times via pollen transfer than they did nearly 100 years ago. Species that are resilient to long-term environmental change may also be the ones subject to changes in pollination interactions.