Peter Rauch wrote:

"But, even more, was the great pleasure of seeing the leaves of those
[eucalyptus] trees with abundant insects on them and insect feeding
holes/scrapes all over the leaves. Everything seemed as one with itself."

Many will know what he meant here, but for those who aren't steeped in
plant-herbivore lore.....

Insects eat plants, and plant-eating insects are eaten in turn by birds.
That's one reason there are a lot of birds in the woods.

When trees such as Eucalyptus are introduced away from their native land,
they don't bring any of their leaf-eating insects with them (they're not on
the seeds, which are fumigated even if they were). And a tree as different
from other trees as Eucalyptus (from its long isolation in Australia) is
not palatable to insects of other parts of the world. Therefore groves of
them are almost insect-free, and thus bird-free. That's why Peter was glad
to see insect damage on those native eucalyptus. The eucalyptus
plantations that have sprung up all over the world are virtual biological
deserts; check it out next time you're in one (there are a few California
birds that seem to like them, for example, goldfinches). The same, of
course, is true when you introduce Douglas-fir into New Zealand, Monterey
pine into Australia, Casuarina (also from Australia, also, interestingly,
attractive to goldfinches) into Florida, etc.--no birds, not much of
anything living in them. This is not the case with all trees; some
introduced legumes, for example, are quite attractive to insects. That's
why, as was written here earlier, you have to pick and choose among nursery
trees if you want to plant non-native species and still attract birds to
your yard.

Many of these quick-growing plantation trees are planted for both timber
and cover and can be quite useful to humans, but there's no way they
replace the native species that were cut down to make way for them.
They're not as valuable as *whatever* habitat they replaced, in fact. I
suppose one could say they're more valuable as habitat than a shopping
mall, but hopefully we won't be faced with those two as the only
alternatives everywhere in the world.

In the PNW, we're worried about saving trees, but trees aren't always the
good guys. To deal with the introduced trees that have wrought such havoc
with southern Florida ecosystems, for example, one might coin the slogan:
"save a habitat; cut down a tree."

Dennis Paulson phone: (206) 756-3798
Slater Museum of Natural History fax: (206) 756-3352
University of Puget Sound e-mail: dpaulson at ups.edu
Tacoma, WA 98416