Thursday, September 13, 2012

Field Site or Classroom?

The answer to this post's title is - both!

This past week I lead a lab exercise I developed for the course I'm TAing this semester, Ecology Lab, out in one of my Glossy buckthorn field sites.  The primary instructor, Professor Catherine Graham, was away on a conference, and rather than teach one of the old lab activities, I decided to get out into the field with my class of 19 students.  I knew I wanted to do a lab that covered some general information on non-native species and going into this TA from the beginning, I thought it would be fun to incorporate my nearby field sites into the course somehow.  So here was a great opportunity!

I wasn't interested in having my class 'do' my field work for me, so I had to come up with something that made sense to carryout in these plots.  I realized that I could plan an activity that answered some question, or curiosity, of mine about these sites, but that I just haven't had the time to delve into myself. For example, looking around my field sites, I'm often curios about what species are in these plots, beyond simply characterizing them as oak-birch-beech upland forests.  So this last Friday I had the students run belt transects in one of my plots and in a near-by section of woods that has only a small number of buckthorn plants present.

I haven't done to many analyses on the data yet, but looking at overall number of plants counted and relative frequencies and densities of individual plant species, a few things definitely stand out.  The most obvious is that maple leaf viburnum is a very common species in the woods around Stony Brook University.  Low-bush blueberry also seems to be pretty common, though more variable than the viburnum.  Another is that there were fewer plants counted in the buckthorn plot.  There are hundreds of explanations for this and almost no way our data will address which explanations are plausible, but as an observation, I thought it was interesting.  As an assignment, I have my students doing a few analyses and making some interpretations and speculations about our observations - I'm really excited to see what they come up with!

Thursday, September 6, 2012

Niche models, the (sub)urban environment, and my uncle's backyard

I use ecological niche models and species distribution models fairly extensively in my research - both my thesis work and side projects.  For some time now my advisor has been involved in projects that link these types of models with population projection models, so when I was thinking about researching the patterns and processes of the invasion of Glossy buckthorn, it made sense to me that I would employ similar techniques.  Additionally, I have only found a dozen or so unique presence records for Glossy buckthorn here on Long Island, so I thought it may be good do a SDM focused just on the island here.  I haven't completed this part of my project, so don't get excited, I don't have any results to share with you yet.  Anyhow, I've spent a fair bit of time gathering more occurrence locations from numerous public lands (parks and what not) in Nassau and Suffolk County, and had been thinking that carrying out an SDM would be pretty straight forward.

SIDE BAR: Looking for invasive species is a bit funny for me.  When I go to a new location that I think is likely to have buckthorn, I'm giddy with anticipation.  I'm excited when I find it and disappointed when I don't.  Now, objectively speaking, if buckthorn is in fact having a strong negative effect on native ecosystems (most likely the case in my New Hampshire populations), then shouldn't I be happy when I don't find it? Yeah, it's complicated I guess...

Ok, back to modeling, and how spending time in the field has affected my thinking.  One thing I tend to think about often when in the field is how Glossy buckthorn got to that particular spot?  Where is the nearest, next-oldest, population?  Glossy buckthorn seeds can be dispersed by any one of the many bird species that eat its fruit, but not too far.  The fruit has a laxative effect (on humans too), so birds don't hold it, or the seeds, for long.  Because nearly all of my field sites are embedded in suburban areas, they all have at least some length of border shared with someones backyard.  At my Long Island sites, I can see backyards from many of my plots.  Initially I hadn't thought much of this, but while visiting my uncle and his family in New Jersey a while I back, I noticed that there in the unmaintained garden next to the patio there was a Glossy buckthorn tree.  Me - "Uncle Joe, did you plant that tree?" Uncle Joe - "Oh no, that came with the house." So there you have it, people in the suburbs may be inclined to plant this tree in there backyard.

What are the implications of this on my models and how I use them?  I'm not sure yet.  On the one hand, it makes me think of possible uses of high-res remote sensing and how it may be used to determine what types of plants are growing in urban and suburban yards.  This technology and its applications are improving rapidly, and we are getting to the point that identification of individual species from satellite imagery may be possible.  (Yeah, that's crazy!) On the other hand, can I use the results of my distribution models to identify distances between populations if plants in your neighbors backyard are actually the source for my populations?  I'm not sure, and will definitely be giving this more thought as the project progresses in the near future.