Biodiversity, community composition, and temporal variability of native bee populations in human-dominated land uses within the seasonally dry tropics

Authors: GALBRAITH, SARA - Oregon State University; PRICE, WILLIAM - University Of Idaho; Griswold, Terry; BOSQUE-PEREZ, NILSA - University Of Idaho

Submitted to: Journal of Insect Conservation
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 9/7/2020
Publication Date: N/A
Citation: N/A

Interpretive Summary: Since land which humans have modified covers much of the world’s continents and continues to grow, it is important to know how well it supports native plants and animals. We studied how three human created landscapes, coffee and teak plantations and pastures. For two years we inventoried the bees on these lands. We found that they were home to 47 genera and 115 species of bees. Bees were more abundant in low elevation pastures than in teak plantations during both wet and dry seasons. High elevation pastures had higher abundance of bees than coffee plantations only in the wet season. Pastures had the greatest diversity of bees. Most of the bees in teak plantations were ones that nest in stems, while oil collecting bees were absent. The study shows how different kinds of human modified lands support different numbers and kinds of bees.

Technical Abstract: Human-dominated land uses make up a large and growing proportion of global land cover, so understanding the potential of these areas to support biodiversity is critical for effective conservation. In this study, we asked how bee diversity and community composition differ among coffee agroforestry, teak (Tectona grandis) plantations, and pastures during the wet and dry seasons in the Nicoya Peninsula of Costa Rica. We sampled over a two-year period using blue vane and pan traps, collecting 47 genera and 115 morphospecies of bees. We collected substantially more bees in low elevation pastures relative to teak plantations during both seasons, and greater bee abundance in high elevation pastures compared to coffee agroforestry during the wet season only. Shannon diversity was greatest in pastures, with an estimated 20 more common species in low elevation pastures relative to teak plantations and 13 more common species in high elevation pastures relative to coffee agroforestry. Teak plantations were dominated by distinct genera during the dry season, hosting stem-nesting genera such as Ceratina but lacking oil collecting groups like Centris and Epicharis. Our findings are likely due to the seasonal availability of floral resources: teak is managed as a monoculture and blooms during the wet season, when fewer bees are active. In contrast, the shade trees common in pastures likely provide nectar, pollen, and nesting substrates throughout the year. Our study provides baseline information on regional bee biodiversity, demonstrating the importance of land use and seasonality in driving bee populations in a seasonally dry tropical agroecosystem.