I went to a super interesting talk this week by Jason Fridley, of Syracuse University. Dr. Fridley’s work revolves around invasion biology, a subdiscipline of ecology. I’ve written about invaders before here…they’re a ubiquitous component of our flora (and fauna to be honest), and thus impossible to ignore.
There were a lot of interesting aspects to Dr. Fridley’s talk (including the unequal exchange of woody invaders between east Asia and North America…east Asia has “donated” way more woody invaders to North America, while North America has donated invasive herbaceous things, mainly asters: this paper is very interesting Fridley and Sax 2014), but one thing that really caught my attention was his research on phenology (which I think is not published yet…when it comes out I will link to it).
His work is all phylogenetically controlled, meaning that he uses a congeneric native species to compare to the invasive species he studies in common garden experiments. This allows for him to determine whether plant traits are truly different because of origin, rather than phylogenetic distance. And in this common garden experiment, after recording phenology for something like nine years (!), he has some pretty interesting conclusions to draw.
One is that the invaders aren’t normally likely to leaf out way earlier than their native congeners…but they are likely to hold onto their leaves way longer into the fall after the natives have lost theirs. This means that they are getting a lot of extra carbon (sunlight) that helps them outcompete native species.
The other thing he mentioned was that invaders are more likely to leaf out early if the winter is mild. Our woody natives require a certain amount of cold weather before they will leaf out, thus they are less responsive to an early spring. This especially caught my attention given my observations on flowering phenology here last week when the weather suddenly got quite warm. Almost none of the natives were flowering, but there were several ornamental species that began to flower as soon as it was warm.
Obviously, my personal anecdotes are not significant data, but my observations are surprisingly consistent with the data Dr. Fridley presented…and he’s been studying this for nearly a decade!