If you don't believe me (and why should you) just look at the work of any noted plantsman and you'll see that most of them have jumped aboard the climate change boat a while ago. Case and point: William Cullina. In my humble opinion, one of the most knowledgeable plantsman on native fauna of the northeast and mid-atlantic states, his books should be on every gardener/designer's bookshelf.... or kindle....or nook, or whatever the hell people store books on these days. In Wildflowers: A Guide to Growing and Propagating Native Flowers of North Americas, published in 2000, long before Al Gore thought global warming was cool, Cullina addresses how our steadily increasing temperatures will impact our native flora, but more importantly what horticulturalists and landscape professionals can do to help our green friends cope. But, the most interesting and scariest part of this portion of the book is a map showing future projected USDA zones in the year 2075. If you live in Boston and are lucky enough (or not so lucky) to be around in the year 2075, hope you like the weather in Atlanta, GA, cause (at least according to the his extrapolated map) were gonna be solid zone 8 (we're currently zone 6). I've included the current USDA plant hardiness zone map for comparison.
While these extrapolations may seem extreme, and granted they were done over a decade ago, they simply illustrate the point that whatever changes happen over the next century, they’re going to be extreme. Aside from the fact that I hate hot weather, a big downside to this is that the New England I grew up in will no longer exist in as little as 2 generations. And with the emergence of a New New England a lot of our native plants that I have come to know and love, the plants that make home feel like home, will simply not be able survive (or at least persist sustainably) in zone 8 heat. And for those that don't succumb to the heat directly, will probably end up victims of pests that would otherwise be kept at bay by the cold. A perfect example of such a plant, that unfortunately will no longer be a part of our natural heritage by the middle of the century is the Eastern or Canadian Hemlock (Tsuga canadensis). Ubiquitous in central and nothern New England, it’s hard to walk through a hemlock forest and not fall in love with these graceful conifers. But unfortunately, while these plants are fairly indifferent to the cold, they languish in the heat and drought, and will simply not tolerate summers where days above 90 degrees F are common-place. And for those few genetic anomalies that somehow mange to survive the heat, they will most likely fall victim to the (fairly) new exotic pest (Wooly Adelgid) that feeds exclusively on hemlocks, slowly killing all trees it infests (see below).
Wooly Adelgid on Tsuga canadensis (Eastern Hemlock) in my backyard
The one thing preventing the Adelgids from wiping out all hemlocks across their entire range is the cold, (-10 degrees F usually kills off most of the bastards), but unfortunately winters where we reach -10, at least in the Boston area, will become increasingly rare. Ultimately, there are a large group of plants across a large portion of New England that are exclusively adapted to our cold winters, and thrive much further north, but generally can not be found south of zone 7 (rarely zone 8), simply because they can not tolerate the heat. These include plants like Cornus Canadensis (Bunchberry), Gaultheria procumbens (Wintergreen), Cyperpedium acaule (Pink Lady Slipper), Linnaeus borealis (Twinflower), and the list goes on.
For those of you who haven't been following the news (and to be honest it wasn't really covered as much as it should have been) we have recently passed a global milestone (as of May 10, 2013), where CO2 concentration has reached levels it hasn't been at in around 3 MILLION years. Obviously that's way before modern day humans were in the picture, so we really have no idea what were in for. What this means practically is that even if we stop all CO2 production tomorrow, there still will be a marked increase in earths global temperature that is now, for all intensive purposes, set in stone (see article). So….. while we should still do all we can to prevent further global CO2 rise, at this point we must prepare for the inevitable. Both designers and plantsman should work together to begin to ferry native plants northward (and perhaps eastward as well), pulling from ecotypes that are better able to withstand heat and temperature extremes. While some may argue that this may jeopardize the genetic integrity of local populations, the reality is that many of these populations may simply not have the genetic diversity or necessary mutation rate to adapt quickly enough to withstand the unprecedented change that lies ahead of us.
No comments:
Post a Comment