Woodlands: The unsung hero of Iowa’s pollinators

April 27, 2023 11:41 AM

“Drab” displays of early spring hold great value

It’s spring, which means I’m keeping close tabs on tree flowering activity. The show can be challenging to spot at first, as many of the early bloomers do not provide the “glam” flowering displays our prairie species are famous for (e.g., prairie blazing star, which I love by the way). Because of this somewhat drab kickoff to spring, tree species and woodlands tend to get minimal respect as far as value to pollinators. This is, in fact, far from the case, as our woodlands provide critical pollinator fuel (i.e., nectar and pollen), larval support, and nesting sites (e.g., hollow twigs, ground cavities).

Woodlands: top contributions to pollinators

As with prairie species, the range of native Iowa trees undertake flowering throughout most of the growing season – creating a continuous show (and value) as the months progress. However, it’s the early bloomers that I want to focus on here. Blooms of species such as willow (Salix spp.), black maple (Acer nigrum), boxelder (Acer negundo), and hackberry (Celtis occidentalis) may often be seen as early as mid-April – representing critical early fuel for recently-emerged (and hungry, I imagine) pollinator species. Again, you need to look close, as their reproductive structures exhibit subdued coloration.

We simply can’t say enough about our 12 native oak species (Quercus spp.) – the backbone of our forest products industry also has critical (and disproportionately large) pollinator benefits. Notably, oaks offer larval support to hundreds of Lepidoptera species (i.e., butterflies, moths) – which in turn support countless songbirds and other wildlife. Foresters often state “if you want to see birds – you need to encourage oaks”.

As we know, trees represent a small proportion of the overall woodland ecosystem. The structure that trees provide (including the forest floor and underground) also benefit a range of pollinators. Ground-nesting and tunnel-nesting bees, bumble bees (including rusty patched), flies, wasps, and beetles utilize soil cavities, dead standing trees, downed woody material, abandoned woodland animal nests, root cavities, leaf litter, and other structure for shelter and overwintering.

Some of the unsung heroes (not showing off too much, just working hard!)

Photo 1 (from left to right): silver maple (Acer saccharinum), willow (Salix spp.), and boxelder (Acer negundo).

What you can do, and resources to assist

Planting and managing for a diverse range of native woodland tree, shrub, and understory species will maximize benefits to pollinators – for nectar/pollen and habitat function. Bonus – species and structural diversity are keys to creating resilient woodlands in general! A tangible example of this would be efforts to control invasive woodlands species, such as non-native honeysuckle and non-native bittersweet. This all starts with walking your woodlands with a professional forester (find yours here) and creating a woodland stewardship plan based on your goals (which may include pollinators!). In addition to the myriad of financial cost-share programs available to woodlands owners (ask your forester), tax programs, such the Iowa Forest Reserve Law, represent critical protection for Iowa’s invaluable woodland resource. For a deep dive into woodland stewardship, consider enrolling in the Iowa Master Woodland Steward Program. For more information on managing woodlands for pollinators, see this Iowa DNR publication.