Dec 19, 2008
Dear Madam/Sir
I am a Distinguished Professor at Oregon State University and have worked and published on genetically modified trees and their risk assessment for nearly two decades. You can see most of my publications, and my CV, at this web site:
http://www.cof.orst.edu/coops/tbgrc/Staff/strauss/publications.htm I wish to respond to some of the comments made by R. Steinbrecher in a previous posting (made at 13:14 today). She attempts to suggest that GE trees as a class are substantially different from annual crops in their characteristics with respect to risk assessment and consideration of receiving environments. This is simply wrong, as explained in response to her comments below.
MY SUMMARY
In short, Norman Ellstrand and others have shown clearly that ALL agricultural crops, GE and otherwise, can pass their genes over very large distances and either establish in wild or feral environments, or mate with wild relatives and produce progeny that can grow in wild/feral places, to one degree or another, and in one place or another, around the world (for example, see his excellent book entitled ‘Dangerous Liasons,’ Johns Hopkins University Press USA, 2003). This can occur via wind, insect, or animal mediated movement of pollen or seeds. In contrast to what R. Steinbrecher says, trees are not categorically different from annual crops in this respect.
The many cases of low levels of transgenes being found in wild or feral populations of annual crops, such as is very well known for creeping bentgrass in the USA, and more recently maize in Mexico, show that all GE crops will move to some degree, over quite long distances and establish in wild/feral populations. Trees therefore do not deserve special or higher stringency risk assessments due to their potential for gene flow in diverse, wild and feral receiving environments.
Instead, the questions that must be the focus of scientific risk assessments are:
1) whether the genes, given their imparted PHENOTYPES, are expected to have an effect of ecological significance ABOVE the already large impact of socially accepted agriculture and forestry practices (with their methods of intensive breeding, use of exotic species, gene flow, and agronomy/silviculture etc., and
2) if the answer to criterion 1) is yes, whether the ABUNDANCE of transgenes is likely to be high enough, in a large enough area over a long enough time, to produce a large impact compared to accepted practices and ecological fluxes in wild environments. Most of these cases of long distance gene movement produce transgenes at a very low statistical frequency (e.g., below 1%), greatly diluting any impact they would have at a distance from the source plantings. It is also unclear that any transgenes in use can provide a selective advantage of such longevity and significance in wild/feral environments, that they would continue to increase. Most transgenes are expected to only provide benefits under domesticated environments such as farms/plantations (e.g., lignin reduction or fast growth that depends on intensive management). Even pest tolerance genes are expected to mainly have benefits in domesticated environments that favor pest proliferation, and have a limited ecological and evolutionary time span due to pest counter-evolution.
REPLIES TO STEINBRECHER
Below I respond briefly to the major comments made by R. Steinbrecher (her comments are in quotes):
"It has been well documented, that trees differ significantly from anual agricultural crops…"
As discussed above, this is simply false
"Trees have a low level of domestication"
This is true for some trees but not others. Many hybrid trees are used that are effectively sterile, and thus almost fully domesticated. There are no agricultural crop species that are full domesticated in the sense that at least some varieties cannot pass genes to feral/wild relatives in some places and cases.
"Trees have a life cycle of decades or centuries"
Of course, but domesticated trees are very often used for short rotation cycles (2-15 years is common). This allows most aspects of risk asssessment to be carried out in a few years; rapid evaluation of tree varieties is common in breeding (e.g., breeding decisions are often successfully made after 2-6 years of assessment, even for trees grown for many decades in commercial plantings).
"Pollen, seed and other reproductive plant materials are dispersed over long distances"
Yes but this is also true for many annual crops, especially given the large scale of their plantings. The many cases of transgene movement from annual crops taking places over kilometers show this to be true. Also, the soil seed bank and persistence of feral relatives in annual species provide means for long term persistence of transgenes; its just a reality in trees. The question is do the phenotypic effects imparted by the genes matter ecologically or economically IN COMPARISON to accepted agricultural/forestry practices.
"Trees affect water and climate systems: forests play essential roles in managing water supply and rainfall, carbon sequestration and also climate regulation."
Yes, but it is essential to consider these effects in a broad context. Agricultural systems with annual crops, due to their large scale and annual planting and harvest cycles, are widely known to have much larger negative carbon and climate impacts than forest trees. GM trees that grow faster, are more stress tolerant, or provide economic benefits and thus favor wider planting, are likely to have far more environmental benefits than use of annual crops. Intensive risk assessment or regulatory requirements whose ultimate effect is to discourage (or preclude, as is now often the case) field research and well-developed commercial applications, are likely to do more environmental harm than good.
"Forests and woodlands, both managed and unmanaged, should thus be categorised as special receiving environment and taken into account for any release of GE trees."
As discussed above, annual crops also release genes that affect wild environments, some are woody communities and some are not. However, a major benefit with genetically modified trees (which for industrial purposes, will have transgenes of benefit under domesticated environments), is that wild forests tend to be robust, having many species and huge amounts of genetic diversity. It is thus very unclear that transgenes can have a significant effect on their adaptability or the ecological services they provide.
However, if genes are developed that really can produce some benefit to trees in the wild, if these act to increase the resilience of forest trees in the face of climate change, associated pest invasions, or other stresses that challenge their ability to survive, the net environmental benefits may very well be strongly positive, not negative. Genes for resistance to exotic pests, such as for the Chestnut Blight under development in the USA, are expected to do just this. That is, to help a species already devastated so it can recover and provide the multitude of ecological services it once did. We can expect many more exotic pests to harm forests in the future; transgenes, if tested and available in a timely manner, may provide a key tool for protection or mitigation—maybe without waiting for species devastation, as has occurred in the past. Special regulations and risk assessment requirements for trees that impede field research and commercial development is likely to do far more ecological harm than good.
