In this fascinating New York Times Magazine article, Tom Christopher goes behind the scenes at a lab doing research on the relationship between weeds and global warming. They found a vacant lot in Baltimore that already had the higher temperatures and higher CO2 levels that scientists are predicting for the future. This became a test plot for what weeds might do in those conditions. The results were pretty startling — giant weeds producing massive amounts of pollen.
But what really interested me was this bit near the end about exotic invasives:
Popular opinion has treated the invasive plants as botanical illegal aliens…Major resources have been devoted to the spraying and
rooting-out of invasive plants in the belief that their removal would
enable an ecological revival….
research, however, suggests that invasive species, at least in some
instances, aren’t so much the causes of environmental degradation as
eco-opportunists taking advantage of disturbed habitats. Or, as the
biologist Andrew MacDougall of the University of Guelph, Ontario, puts
it, the invasives may behave more as “passengers” than as “drivers.”
Field research, he went on to say, has demonstrated that when invasives are removed, the native plants don’t necessarily grow back. In some cases, their decline only accelerates. The researchers
concluded that rather than serving as drivers of change, the foreign
grasses were functioning more in the role of passengers, merely filling
in as the natives disappeared. In fact, the foreigners seemed to be
serving a stabilizing role.
Could it be that the spread of invasive weeds does not cause a decline in native plant populations, but merely happens after native plants have declined for other reasons, like climate change or habitat disruption?
And if so, does that change anything? Does it let invasive exotics off the hook?
Discuss amongst yourselves.