This is a copy of one of our Facebook posts.
If you’ve been following us for a while, you might already know that our focus is on local efforts to improve
biodiversity. That can be broken down into two steps:
1) Remove invasive plants
2) Add native plants
I enjoy hearing park visitors expressing pleasure at the prospect of seeing beds of flowers instead of just
patches of weeds, but I’d like to dig deeper into this topic… WHY the choice of plants matters and HOW
these plantings can support local biodiversity. This is a big, complicated topic so, for this post, I will just focus
on bees.
* Minnesota is home to 500+ species of native bees. Most of these are solitary bees (a single female who
prepares a nest, collects pollen, lays eggs, and then dies before they hatch). Some nest in old plant stems
or beetle-tunnels in rotting wood, but most nest underground. These native bees have developed close
relationships with our native flowering plants over millenia; about a third of them are what we call “pollen specialists,” meaning that they only collect pollen from certain plant genera or species. If those plants are
not in the environment, then neither are the bees.
* Because of changes in land use over the past century or two, most native plant species have been replaced
with turf grass and non-native flowering plants (intentionally) and invasive species/noxious weeds
(unintentionally). And that is one of the reasons that many native bees are struggling.
* That’s where we come in… working hard to remove invasive plant species and replace them with a diverse
mix of native vegetation. Generally speaking, the more diverse the mix of (site-appropriate) native plants, the
more diversity of insect life they can support. WITHIN that mix, we try to include a large number of flowering
plants that support the pollen specialist bees. This first image is some of the keystone plant species and the
local pollen specialists that they support. It also lists where they’ve been documented on iNaturalist.
* If you’ve not already overwhelmed by all this information, there’s another layer of complexity I can throw in.
There’s the question “which pollen specialists are most in need of help?” and there’s also the question “which
pollen specialists are most likely for us to help?” It’s that second one that I’m currently focusing on. I’ve
found at least 29 species of pollen specialist bees that have been documented in the Twin Cities Metro area.
Does that mean that all of those bees will come to our parks if we plant the flowers they need? No. We don’t
know how far they will travel when searching for new nesting sites… maybe a mile or more. And that’s one of
the reasons why the creation of pollinator corridors is so important… to create spaces where these tiny
creatures can live and move through the area and hopefully support genetic flow (rather than inbreeding).
* So… there are currently FOUR pollen specialist bees that we can support in Arden Hills NOW. They
are listed in bold in the first image and there’s more info about them in this second image (below). What they
need are: Golden Alexanders (Zizia), coneflowers (Rudbeckia & Ratibida), asters (Symphyotrichum &
Eurybia), goldenrod (Solidago), early sunflower (Heliopsis), and coreopsis. We’re working to incorporate as
many of these into park plantings as we can. (And you can support these bees at home by including these
plants in your landscaping, as well as un-mulched soil where they can dig their nests.)
* And a final note for today: Whenever possible, we can include the other keystone species and hope that,
someday, enough homeowners and business owners include native vegetation in their landscaping so that
those other populations of pollen specialists (such as the Agile Longhorn Bee spotted at the Bell Museum)
can make their way to Arden Hills.