Over the past two years in my role as an editorial and journalistic reporter, I’ve become more and more interested in earth’s millennia long history. The theories of evolution, ice-ages, periods of warming and continental shift have all opened up to me as they never did in high school (probably because I went to a Christian school in the late 90’s).
Of all that I’ve learnt, I have found a particular attachment to the Northern Hemisphere. Its formational changes at the hands of glacial plates, sliding south then north again; the mass-extinction of the North American mega-fauna; and the ever shifting landscapes have compelled me to know more, as my own countries history never has.
So I find myself once again drawn to the news that a new study predicts an evolutionary relocation for 130 North American tree species.
The study has been conducted by Daniel W. McKenney along with his colleagues at the Canadian Forest Service. His study was based upon extensive data-gathering, and as a result was more comprehensive than previous studies. Data collection effort’s extended into Canada as well as focusing on the United States.
McKenney found that if the trees responded to climate change by dropping their seeds towards more favorable locations northward – away from warming areas closer to the equator – ranges of the tree species studied would move northward by some 700 kilometers. Sadly, they would also decrease by an average of 12%, with some species increasing and others decreasing.
Conversely, if the species were unable to disperse to areas healthier for them, the range shift was 320 kilometers, but the reduction was “drastic” at a 58% drop. The authors of the study though believe that most species will fall somewhere between these two extremes.
As part of the study the team used heat and moisture – two important gradients for plants – as climate measures. Two scenarios were modeled, one assuming that CO2 levels would decrease, and one predicting that they would increase. Both scenarios were investigated with three well-known models of Earth’s climate, and all produced broadly similar results.
The authors noted that their study focused only on a sample of the 700 tree-species in North America. They suggest that under a climate change, new species may sprout and colonize in the southern part of the continent, ranging from the tropical conditions.
So as Americans worry about the continued droughts being suffered down south, is anyone really looking at what is happening north?
American Institute of Biological Sciences via PhysOrg – Climate change predicted to drive trees northward