Trees for bees
In recent years there has been an increasing awareness of ways that people can support pollinators by better managing their lawns and gardens. Unfortunately, it seems like much of the attention and debate has had a well-meaning but often misguided focus on turfgrass lawns and their associated weeds.
As a bee scientist, I feel like the whole debate about non-native lawn weeds like dandelions actually distracts from much more effective strategies to help pollinators, such as trees for bees. I agree everyone should absolutely stop dumping pesticides and fertilizers on their lawns (and think about ditching their lawn altogether), but when it comes to the sheer amount of resources provided to pollinators in the spring, flowering trees will win out every single time.
When deciding on the best ways to help pollinators, we need strategies that match with our ecology and climate. As has been discussed elsewhere, one of the issues with strategies to help pollinators such as “No Mow May” is that they were originally developed in Europe, so simply adopting them in the United States may not be a perfect fit.
In one informative study, scientists compared the floral ecology of bees in Michigan and England, and they found that there are big differences in the seasonality and ecology of many species. For example, the United States hosts many more species that depend on spring-flowering plants including spring ephemerals and different trees and shrubs. In contrast, they found the English bees they studied were much more generalized and were active the whole season rather than just in spring.
Based on that research, it’s clear that trees for bees can be an effective and ecologically-relevant strategy to help many of our spring-flying bees. With that in mind, I wanted to offer a (non-exhaustive) list that highlights some of my favorite flowering trees for bees, listed in roughly the order that they bloom in spring. These are all trees I observed this spring and it reflects my location in Minnesota, but is applicable for many areas of the northern US that have distinct seasons. It’s also particularly relevant given that a lot of new trees are being planted to replace the ash trees killed by the emerald ash borer.