Boreal pollinators in a changing climate : the effects of forest composition, structure, and microclimate

Abstract

The boreal biome, the world's largest contiguous forested region, is undergoing significant changes due to rising global temperatures. This warming is impacting the interactions between trees, understory plants, and pollinators, which determine the species composition of understory plants and their pollinators, as well as essential ecosystem services such as berry production and pollination. However, our current knowledge is insufficient to predict how changes in climate and land use, the main drivers of global change, will affect this system. The objective of this thesis was to enhance our understanding of the interplay between forest structure, microclimate, and pollinators. My studies highlighted the limited understanding of climate change effects on boreal pollinators (I), emphasized the crucial roles of forest density and overstory species composition in regulating understory microclimates (II), which in turn impacted pollinator foraging behaviour (III) and their species diversity (IV). When assessing the effects of climate change on boreal plant-pollinator interactions, most studies use proxies to measure pollinators, omitting their taxonomic identities and limiting our ability to evaluate the resilience of specific interactions (I). Forests buffer extreme temperatures, providing refugia for species affected by warming, with higher forest density offering the best temperature regulation relative to macroclimate. Both broadleaf and conifer trees provided these benefits, though most broadleaf trees allow more light (II). Since most boreal pollinators are ectothermic insects, ambient temperature was the most important factor driving their foraging rates, while microclimate affected their foraging duration (III). However, the richness of flower-visiting arthropods was positively influenced by low forest density and broadleaf dominance, whereas microclimate may play a smaller role (IV). Collectively, these findings suggest that forest management could enhance pollinator habitats and resilience against climate change, but further research is needed to refine these strategies and understand species-specific responses.

Keywords

forest management, Diptera, Syrphidae, understory, temperature buffering, climatic refugia, phenological mismatch

Published in

Acta Universitatis Agriculturae Sueciae
2024, number: 2024:65ISBN: 978-91-8046-356-0, eISBN: 978-91-8046-392-8Publisher: Swedish University of Agricultural Sciences

SLU Authors

• Diaz Calafat, Joan

  • Southern Swedish Forest Research Centre, Swedish University of Agricultural Sciences
    

UKÄ Subject classification

Climate Research
Ecology
Forest Science


Publication identifier

DOI: https://doi.org/10.54612/a.18rsgbp5pk

Permanent link to this page (URI)

https://res.slu.se/id/publ/130460