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TT: Locusts, Diatribe 1
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I agree with Gary that we sometimes have to take what we can get in urban
areas. There is, however, a great danger in this, in my opinion. There are
a number of trends worldwide that favor pioneer, "weedy" trees:
urbanization, abandonment of agricultural land, forest clearing (especially
tropical), silviculture, poor forestry practices, etc. The weedy trees are
not only becoming dominants in and around urban areas, but in rural as well.
Thus we see Ailanthus and Robinia thriving, even as sugar maple and Northern
red oak decline in abundance and vigor. In Kuala Lumpur, Malaysia, I
observed that 80% of the street trees were non-native pioneer trees, even
while the surrounding forest contains about 6,000 native species.
It seems to me that one of the goals of community forestry should be to
create a mosaic, in which later-successional trees can thrive. These later
successional trees have many of the properties we desire in the urb: long
life, good crowns with dense shade, strong branch crotches so they don't
break up. These are precisely the traits missing in pioneer trees. The
establishment of a canopy of trees, especially with a good shrub layer, will
prevent pioneer weeds from becoming established.
Perhaps this is pie-in-the-sky, and we certainly will always have to live
with some of these pioneer trees (and some of them can be nice in the right
place). If we can solve the difficult problems of soil compaction in urban
areas, we can have a healthier mix of trees and a diverse urban forest.
Tom Kimmerer
Forest Biologist
University of Kentucky
Lexington KY 40546-0073
606-257-1824
Fax 606-323-1031
tkimmer@pop.uky.edu
Visit the TreeWeb at http://quercus.uky.edu
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