We hear a great deal about programs to encourage us to plant a tree. It always sounds good, because most of us love trees, appreciate their value to us emotionally and ecologically, and understand the importance of wood and paper products that come from trees. But when I scratch the surface of the suggestion to plant more trees for the environment, I find it is more confusing than amusing.
The supposition in these tree-planting programs seems to be that by planting a tree seedling or tree seed that we are rebuilding our forests. But for this to be correct, it matters where you plop the baby tree, and what species it is that you are plopping. Most ecologists are completely convinced that we should encourage vegetation native to a particular region to grow in that region. I have often lamented in this blog the invasion of our local habitats by non-native plants. So when someone gives you a tree seed and tells you to plant it, you need to know what species it is and if that species is indigenous to your area.
This week on Treehugger I read about a new "invention" where tree seeds are embedded in cardboard boxes. When you are finished with the box, you bury the cardboard and a tree grows in that location. Apparently, the company, which is called Life Box, has chosen tree seeds that are native to every major region of the country. They think this has covered any criticisms about non-native species or invasive plants getting where they should not be (see comment by MycoKat here). But it is not as simple as that. For example, white birch is native and common in forests about 150 miles east of Ithaca, NY, where I live, but it is not found in the forest around Ithaca. If those seeds were used in their boxes, would those boxes only be used for shipping to eastern NY and not central NY? I doubt it. Humans have this tendency to superimpose their mental image of a map on the landscape, and it rarely matches the ecological reality that has been in place for centuries.
Let's assume you now have the seed of a tree species that is truly native to the exact location where you live. But then, where do you put the darn thing? You can always plant a tree in your front yard. Nothing wrong with that. That tree can be appreciated for its beauty for decades, and it produces oxygen and sequesters carbon dioxide during its life just like the next tree. But this has nothing to do with regenerating a forest. If you were interested in helping out our forests, I guess you might plant the thing next to or inside an existing forest. But that is really unnecessary. Forests produce plenty of seeds from the trees that are already there and don't benefit from our putting one more seed in the ground. Evidence of the abundance of forest tree seeds can be found in your gutter every year, when you clean out the maple, ash, and elm seeds that have blown in there. Squirrels and blue jays are moving nut seeds around the forest and planting them all the time. Let nature do its thing. It knows more than we do anyway about where to put these propagules.
So where should you put tree seeds if you have them? I suggest putting them where they are really needed; put them where there is absolutely no forest at present, but in a location where there WAS once a forest that contained the species of trees you are about to plant. An abandoned lot in a city would be a great place to undertake such a project, assuming there is still viable soil there. That is, create a forest, however small, where there was not one before (or, at least, not in a very long time). Or what about an area that was once mined for some commodity, where the vegetation was skimmed off the surface of the earth for miles around? That area needs help. These examples would be true efforts at restoration. Abandoned hayfields or meadows rarely need this kind of help; seeds from trees in nearby forests will find their way there.
My point is that planting a tree sounds as American as apple pie. What could be wrong with a wholesome activity like that? But this "movement" has all the characteristics of a program that makes us feel good without accomplishing anything substantive for the environment. As a conservation biologist, we don't need more trees, we need more habitat. And habitat, whether it is forest, or prairie, or marshland, mostly needs protection to develop on its own. Only then will it contribute to viable populations of biodiversity, as well as provide all those "ecosystem services" like carbon sequestration that are so important.