So much has been said and written about climate change and global warming that there’s not much I can add that hasn’t already been covered. However, personally, I’ve failed to see much attention given to the global impact of all the exotic and invasive species that have been relocated and introduced into ecosystems, thousands of miles from their home range.
This planet has experienced many climate changes over its lifetime, ranging from uninhabitable to tropical to ice ages. Species have appeared, prospered and then disappeared when climates adversely changed. So in many ways what we’re witnessing now isn’t all that new, albeit fodder for debate. What is new is the rapid global relocation of so many species, thanks to a globally mobile economy that results in a potential witches brew of assorted alien species to be leapfrogged all over the planet.
Last week this column covered the many new invasive insects that are threatening to decimate many of our indigenous tree species that comprise the majority of our nation’s forests. We already know the impact exotic species can have on their new ecosystems, thanks to what has occurred in the Great Lakes and the Mississippi River system where exotics have gained firm footholds and are negatively impacting indigenous species. But with the accelerated pace of alien introductions, what will be the long and short term impacts on our outdoor ecosystems? With few or no natural enemies present in their new environment, alien species normally thrive, at the expense of the indigenous ones.
And while we may be concerned over climate changes that could negatively impact us and our accustomed environment, few seem to also consider the potential damages that are resulting from literally tens of thousands of area-specific species being relocated all over the globe. The domino effect of this “alienation of environments” could be just as damaging as climate change, by affecting agriculture, public health and the abilities of the areas’ natural ecosystems to sustain themselves. Recent studies by the Environmental Protection Agency show that as the Earth's climate heats up, invasive species will hold the advantage over native plant species in spreading across the countryside.
A Princeton University study concluded that in many cases, a warming climate will provide more welcoming conditions for invasive plants to get a foothold, spread quickly and crowd out native species. Of course not all our alien species are recent arrivals. Many have been here since European settlers spread across the continent and nonnative weeds and plants followed them, sometimes literally. Even one of the West's most famous symbols, the tumbleweed (also known as Russian thistle) isn't a native plant. It was brought from Russia generations ago. In addition to the large variety of alien flora, many of our more common fauna came from other parts of the planet -- pigeons, English sparrows, startlings, black and Norway rats, feral hogs, burros and horses, gypsy moths, and several other long-term non-native species.
