CO-Horts Blog

Thursday, September 13, 2018

Best plants to create habitat

One of the best reasons to grow native plants is that they do more to provide ecosystem services than non-native plants.  With pollinators and birds in decline, it’s a great way to help. While everyone remembers from basic science classes that plants are at the bottom of the food chain, it is important to realize that some plants pull more weight than others.   For starters, many non-native plants don’t support any insects at all. This is because about 90% of herbivorous insects are specialists to one degree or another.  The insects simply don’t recognize the alien plant as food.

Here is where a functional definition of a native plant can be useful. Entomologist Doug Tallamy (author of Bringing Nature Home) uses this one: is a plant or animal that has evolved in a particular place long enough to be able to establish the specialized relationships that are nature.   Alien plants just have not been around long enough to develop these relationships with the local fauna.
Further research by Tallamy’s lab bear this out; they have found that some oaks have up to 557 species of moths and butterflies, Prunus like wild cherry and plum can yield up to 456 species; and maples support up to 297 species. Introduced species such as Bradford pears have almost no species on them. When it takes over 6,000 caterpillars to raise one brood of chickadees, it is clear which species will help birds  and other insect-eaters the most.

Clearly, the moral of the story is that to support pollinators and birds, plant native plants.  But even within native plants, some species are more helpful than others.  Tallamy’s research has found that just five percent of the local plant genera produces about seventy five percent of the insect food that drives food webs. Including these powerhouse in your garden (even if you otherwise have lilacs and petunias) will do much to support bird species.  And the birds will keep the caterpillars from overrunning your plants. If you have breeding birds in your yard, you won’t see many caterpillars because the birds will have eaten them.

So, how to figure out which species are the powerhouses in our area? A really cool site where you can find native plants for your zip code – ranked by how many caterpillar and moth species they host- can be found at (based on collaborative work with Dr. Tallamy).
Typing in the zip code for Boulder as representative of the Front Range, I get results for both herbaceous plants and trees in order of how many insects they support.  Granted, this website is still in Beta format, and is not perfect, but it is nonetheless a terrific start.

So, the winners of the best habitat plants in the herbaceous category for butterflies and moths for the Front Range are….. drum roll….

Goldenrod (Solidago spp.)
Sunflower (Helianthus spp.)
Strawberry (Fragaria spp.)
Lupine (Lupinus spp.)
Sagebrush (Artemisia spp.)
Violets (Viola spp.)  (We do have native violets, although they are hard to find in nurseries).
Rabbitbrush (Chrysothamnus spp).
Goldenrod lights up the late summer garden and is fantastic for habitat

And in the woody category they are….

Willow (Salix spp.)
Poplars – aspen, cottonwoods (Populus spp).
Prunus (chokecherry, plum) (Prunus spp)
Oak (Quercus spp – esp. Quercus gambelli here)
Pines (Pinus spp)

Chokecherries have fragrant spring flowers and edible fall berries 

You may even have some of them in your yard now, but it couldn't hurt to plant more.

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