Janet Marinelli recently wrote an opinion piece entitled “As World Warms, How Do We Decide When a Plant is Native?” She asks what role gardeners should play in helping plant species migrate as temperatures rise and change botanical zones. She concludes that Emily Dickinson‘s movement of magnolias (Magnolia tripetala) to her homestead in Amherst, Massachusetts may be more appropriate than Thoreau‘s and Muir‘s desire to leave the wilderness alone.
Here are my thoughts:
The question is though-provoking. There have been a number of articles written by the naysayers that focus on a similar premise. This Yale article, like most of the others, does not address the problem of lost biodiversity created by the horticultural or the personal movement of the native plants. Biodiversity is maintained when the native plants are allowed to migrate on their own (adaptive evolution). Horticulturally or personally assisted movement of native plants, just like creating cultivars, limits the biodiversity continuum. These plants are no longer native; they are naturalized.
One other important fact not addressed in this article is the use of the ecoreogions map instead of the hardiness zone map to document the shifting of plants. The hardiness zone map only takes into account sunlight; hardly relevant to a native plant in its place. Native plants out of place are not native plants.
Just an added note: mastodons, giant ground-sloths and other megafauna are part of the biodiversity continuum.
I’d be interested in reading your thoughts on this question. Please leave a comment.