Context Land-cover and climate change are predicted to affect pollination and plant reproduction but few studies have tested how these stressors interact to drive pollination success.
Objectives Using a 9-year dataset we tested whether climate interacts synergistically with forest loss and fragmentation to affect pollination of a tropical understory herb, Heliconia tortuosa. We hypothesized that hot and/or dry conditions might amplify effects of habitat loss and fragmentation, leading to declines in plant reproduction.
Methods We collected data on pollen tubes, fruits and seeds of H. tortuosa in a mensurative experiment representing gradients in forest amount and patch size (N=40 focal-patch landscapes). We modeled these reproductive metrics as a function of landscape composition, configuration, precipitation, temperature, and statistical interactions among these variables.
Results We found little support for synergistic landscape and climate effects. However, probability of fruit production decreased in wet years, and increased in large patches embedded in more contiguous forest landscapes. Counterintuitively, small patches in heavily deforested landscapes also exhibited a high probability of fruit – perhaps due to constraints on hummingbird movement. Amount of H. tortuosa fruit decreased in wet years and in deforested landscapes.
Conclusion Although we did not detect synergistic effects, climate and landscape structure do have independent impacts on plant reproduction. Unfortunately, the regional climate is predicted to become wetter and the forest remains fragmented, with potential negative consequences for Heliconia reproduction. Decline in this common species is likely to have cascading consequences for hummingbird pollinators, and subsequently other hummingbird dependent plant species.