Arbor Day in Georgia

Arbor Day is celebrated on different dates throughout the U.S. due to climate differences. For Georgia it is the third Friday in February – this will be February 17^th in 2012.  National Arbor Day gets a lot of attention in late April, but in Georgia it is better to plant trees much earlier when trees are dormant, temperatures are cool, and winter rains are possible.

With Arbor Day coming up this week, I’d like to talk about the following three points:

• Why it’s important to plant trees
• Why it’s important to plant native trees
• Why some native trees might be a better choice than others

Importance of planting trees

When my kids were in elementary school I would organize an Arbor Day event on behalf of the PTA.  Most years we gave out seedlings that we purchased from the Georgia Forestry Commission.  The kids loved the event, and the older ones could easily answer the question about what benefits do trees provide: Oxygen, shade, food for us and wildlife, shelter for wildlife, beauty, and protection against soil erosion.  They also provide wind breaks, and they can provide privacy.

Why native trees

So you might think that it doesn’t matter what kind of tree you plant, but it does matter.  Native trees support native insects and so they also support the creatures that rely on those insects – the whole local ecosystem has grown up around native trees and it depends on them.  There are insects whose larval form feed exclusively on a plant or group of plants – insects such as the eastern tiger swallowtail butterfly (Papilio glaucus).  Eggs are laid on the leaves of wild black cherry (Prunus serotina) and tuliptree (Liriodendron tulipifera); the caterpillars that hatch will consume a small amount of the overall foliage.  Choosing to plant a non-native tree instead reduces the biomass available for specialized insects, resulting in fewer insects overall.  There are studies that show that specialized native insects (most of what we have) cannot adapt to eat non-native plants. Fewer insects equals less food available for the birds that feed these caterpillars to their chicks.  

Why some native trees are better choices

In the paragraph above I talked about why choose a native tree over a non-native one.  Now I'll like to talk about why choose particular native trees rather than just "any" native tree. Think "native" on a smaller scale - the environments in which you live need the indigenous plants that support them.  For example, growing blue spruce (Picea pungens) in north Georgia adds nothing to the local environment - it is as alien to the insects that live here as a plant from Europe because it is native to the western United States.


Consider also diversity when choosing a tree.  If your area is full of oak trees, consider planting something else instead of another oak.  Doug Tallamy, entomologist and author of Bringing Nature Home, has created a top twenty list of woody plants (and perennials) for the mid-Atlantic region.  This list is based on the number of different species of Lepidoptera they support - those caterpillars that the birds love to eat!  While oaks are first on the list, adding a hickory (Carya sp.) or birch (Betula sp.) to your yard would allow you to support much more biodiversity.  

Take a survey of not only your yard but the areas around you to see what native trees are already there.  But don't that list stop you from indulging in something you love like the iconic flowering dogwood (Cornus florida) or the early flowering redbud (Cercis canadensis).  If you want to attract more birds to your yard with fruiting trees then consider serviceberry (Amelanchier sp.) and hawthorn (Crataegus sp.).

So when Arbor Day comes this Friday, consider planting a tree for all the right reasons.  And if you have kids or grandkids, be sure to involve them and talk about the reasons that we plant trees and conserve them.

Eastern tiger swallowtail butterfly (Papilio glaucus)