From: Jim Diamond <[log in to unmask]>
Date: Wed, 4 Apr 2001
To: [log in to unmask]
Subject: good article on GE'd trees
There is a very full "briefing" titled "The Biological Politics of
Genetically Modified Trees" available at
http://www.wrm.org.uy/subjects/trees.html -written by Viola Sampson and
Larry Lohman. It's one of a series of "Cornerhouse Briefings."
It's much too extensive to reproduce here, but covers the many issues
involved very well. I'll excerpt a couple of paragraphs below, but there's
much more good stuff to be found in the article (especially after you get
past a pretty slow-moving introduction):
The need to prevent GM trees and their genes from invading native ecosystems
is clear. Low-lignin trees have the potential to disrupt the forest
composting cycle responsible for unique soil structures and nutrient cycling
systems. An influx of low-lignin trees vulnerable to damage from insects and
other herbivores, moreover, could result in pest population explosions.
Insect-resistant GM trees have the potential to disrupt insect population
dynamics and also are likely to enjoy an invasive advantage over forest tree
species. More generally, invasions of GM trees could threaten the diversity
of the forest gene pool from which trees are selected for conventional
breeding -- a reservoir already reduced by selective logging practices.
Because trees are even more genetically compatible with their wild relatives
than highly-bred agricultural crops, GM "escapes" are especially worrisome
in forestry.
Although the need to keep GM and non-GM trees separate meshes neatly with
industrial incentives for simplifying land use to a single species or
variety of tree, the problem is that isolation is virtually impossible in
practice. For one thing, plantations often border wild forest systems, and
indeed are often set up on land cleared of old-growth forest. For another,
tree pollen can travel vast distances. On the treeless Shetland Islands,
pollen was found from forests more than 250 km away across the sea. In
Northwest India, windborne pine pollen was found 600 km from the nearest
pine trees.
Crucial forest pollinators including flies, butterflies, ants, beetles,
aphids, bumblebees and honeybees are also notably indifferent to posted
boundaries between GM and non-GM domains. Seeds are equally difficult to
limit to a single geographical area, some being carried around by
fruit-eaters while others are wind-borne or water-borne. In fact, it is seed
or vegetative fragments which feature in the best-documented cases of
long-distance gene flow, for example the establishment of plants on new
continents. Many trees can also spread through the distribution of broken
twigs, while others send suckers up from their root systems. A single aspen
in Utah, for example, boasts 47,000 trunks springing from its root system,
and covers 42 hectares. Trees can also grow from stumps left after felling.
In sum, trees may be even more adept at spreading their progeny than crops,
and once in the wild, a single GM tree could survive for hundreds (perhaps
thousands) of years.
COMMENT: Highly recommended reading. Once again, it's available at
http://www.wrm.org.uy/subjects/trees.html
Jim Diamond
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