Pollinators

Pollinators are essential to the function of terrestrial ecosystems and provide us with valuable pollination services. Studying pollinators therefore allows me to learn about basic ecology (e.g., what limits the abundance and distribution of species?) and conservation (e.g., how do we effectively protect pollinators?). These questions often go hand in hand.

Habitat loss and degradation are leading threats to pollinators. For instance, converting native grassland or forest habitat to intensively managed agriculture can reduce the abundance and diversity of floral resources in the landscape that are required by pollinators. Exacerbating the impact to pollination services, habitat loss can affect bees – the most effective pollinators – more strongly than other insect pollinators like flies and beetles (Spiesman & Inouye 2013).

Local disturbances, such as crop harvesting, can also have variable effects on pollinators. Harvesting bioenergy grassland fields, for example, can enhance floral abundance and diversity by knocking back competitive dominants and opening space for new plants to grow. But only bee species that nest safely below ground see the benefit of greater resource availability. Harvesting can negatively affect species that nest above ground in vegetation because their nests are more likely to be destroyed in a harvest (Spiesman et al. 2018). These types of taxon-specific effects should be considered in conservation and mitigation strategies.

Bee conservation often focus on increasing the abundance and diversity of flowers. But it can be difficult to tell whether bees are merely aggregating in high-flower areas or if flower additions help increase population growth. This distinction is vital for effective conservation. Using experimental bumble bee colonies, we found that increasing the abundance of a few dominant floral species – rather than abundance of many floral species – increased bumble bee reproduction (Spiesman et al. 2017). Thus, our study supports the idea that increasing floral resources is effective for bee conservation but that fine tuning may be required for particular bee species.