Arbor Day, April 27, is nearly upon us. Many of us are receiving solicitations in the mail about ordering trees through the National Arbor Day Foundation. But you should think carefully about what trees to order.
The Arbor Day Foundation remains behind the times when promoting tree-planting, because they barely mention problems with invasive trees on their site, and in none of the junk mail literature I have received. Although an entire page is devoted to invasive species that harm trees, the only reference to invasive trees is buried its FAQ:
10. Are the trees offered by the Foundation invasive?
The Foundation follows the guidelines of the National Invasive Species Information Center. Plants found to be invasive or problematic by this agency are removed from the lists of trees and shrubs offered by the Foundation. In addition, we take into consideration recommendations found in the publication entitled, Invasive Plants, Changing the Landscape of America, by the Federal Interagency Committee for the Management of Noxious and Exotic Weeds.
Naturally I’m not complaining about their policy, it shows they are at least paying some attention to the problem of invasives. What I object to is that the NADF, throughout the web site, promotes and sells trees purely by horticultural zone, as does every gardening catalog. The gardening catalogs, though, are about business, and up to this point, businesses spreading species around have not been held accountable for invasive outbreaks, so in their case this policy is understandable.
However, the NADF promotes itself as an organization that cares about ecology and the environment. Aside from fortunately not selling nasty invasive trees such as Russian olive and saltcedar, they do absolutely nothing to promote the idea that we should be cultivating local species, which is by now a standard ecological concept. Even if your exurbian front yard is hardly definable as a natural habitat, NADF should be attempting to instill in you the idea that what makes ecology important, and sustainability possible, is the recognition that certain species of trees belong in certain areas because they are used to interacting with the other species found in that area. Such a visible organization could be making great strides in promoting local habitat ecology, but they are making absolutely no effort to do so.
What difference does it make, if none of the trees they sell will become invasive? First of all, every time we move a species, or even an individual, around to where it doesn’t belong, we are conducting an biological experiment. Maybe there are no problems 9,999 times out of 10,000; but the more often we do this, the more often number 10,000 comes up.
In addition, the homogenization of the planet comes with several costs. One cost is giving up the buffer that having millions of species across hundreds of ecosystem provides against our own foolhardy exploitation of resources. The honeybee “crisis” everyone is clamoring about now is a perfect example of this. Bring an alien species to a large region to replace hundreds of native species that could do the job, albeit less efficiently from a human perspective, and one disease, one environmental problem, and you are in trouble.
Another cost is to our own human sense of place. When distinctive plants and animals disappear from places – a good example here is of pacific islands, whose endemic plants and animals have been decimated, and replaced with a few ubiquitous species now found on nearly all the islands – we lose some of the wonder we have for the natural world. In fact, each successive generation has less appreciation its own corner of the planet, because fewer species remain to distinguish it from anywhere else on earth.
Perhaps these issues are just too abstract for an organization that wants to promote one simple idea, that “trees are good” – not even always true, in an ecosystem that was historically treeless, another distinction NADF fails to make in its black-and-white view of ecology. Perhaps there’s no point in anything but pooh-poohing those of us who wish for a different ethic – many of these have been cultivated for generations, and some are human-created hybrids, so really what difference does it make where we plant them? I argue only that these are minor points in the greater struggle to convince humanity, especially that small portion of humanity that has the time and money to support any sort of environmental ethic that it chooses, that ecology and biodiversity are not actually words that can describe numbers of species over an entire planet. They much more aptly describe the mosaic of species assemblages that found a way to evolve in every possible environment that is found on earth. If we lose that idea, then biodiversity itself is a meaningless concept.