Management and Resilience

The White Mountains of New Hampshire is the place that inspired me to study ecology. So when I was coming up with my PhD project I wanted at least some of my field work to be in this region.  (As an aside, one of the bonuses of the PhD program at Stony Brook is that you can develop a project independent of your adviser's research program, so to some extent, you can choose where you want to work.) In fact, while I was developing my project, I contacted the Botanist for the White Mountain National Forest and asked him if there were any non-native plant species he thought were particularly concerning.   Glossy buckthorn - that was his first answer.  So as I've described a bit here, in 2009 I set up my first transect about a 1/2 mile or so from the trailhead of the Winniweta Falls Trail.

I'll leave a discussion of the physical characteristics of this site for another post. Today I want to share some of my observations from here, which I think demonstrate the tenacity of Glossy Buckthorn. In September of 2010, I marked 147 individual plants along three 30m transects in a field heavily infested with Glossy Buckthorn.  This field was just one of several open fields in the area (along the Jackson Ski Touring trails, for those of you who are curious) that had a high density of buckthorn.  I believe these areas are maintained as open fields to provide wildlife habitat for organisms such as moose.

Dense Glossy Buckthorn cover in an open field near Winniweta Falls Trailhead

A little out of the field of view of the picture above, I set down one of my three 30m x 1m belt transects, which  contained 115 buckthorn plants.  As you can see below, many of these plants are taller than my 2m measuring pole.

Transect 3 - Many buckthorn platns taller than my measuring pole!

I received permission from the Forest Service to sample at this location, I even have a letter on official USFS letter head, so I was pretty confident that my site would go undisturbed after setting up my transects and tagging the plants.  Plus, this isn't a high traffic area for hikers.  But between my 2010 visit and my 2011 visit there were to major storms, including Hurricane Irene, that flooded the area, so I was expecting some impacts.  But I was pretty shocked when I showed up the Fall of 2011 to this!

Winn Falls site after mowing

And here's that transect that had all of those greater than 2m tall plants.

Transect 3 - after mowing

As it turns out, there was some miscommunication and this locale was approved for a mowing.  It would be foolish to harbor any bitterness about a destroyed site. After all, the forest service is just trying to manage this invasive plant and keep this wildlife opening, well, open.  But I do have to wonder if the mower thought twice about running over orange flags, plants marked in a line with flagging tape, or plants clearly marked with shining little metal tags.

So, seeing this for what it was, I collected the tags I could find, measured the basal diameter of the plants who still had tags attached to them (hey, after all, that's a years worth of growth in basal diameter I could measure there, even if I couldn't say much about height), and left with the plan to come back in 2012 and see what happens.  You see, buckthorn is notoriously tenacious - it re-sprouts quite readily.  The most affective way to manage buckthorn is to cut it and immediately apply a weed killer (this is based on research reported in several papers, many from the Natural Areas Journal).  I had a suspicion I would come back in a year and see plenty of re-growth. Of the 147 plants originally tagged, I was able to leave 44 and recover 45.  That left 58 unaccounted for.  Given how high the flood waters came from the two large storms that hit this area in 2011, I suspect that many of them are in the Ellis River or along its banks. This season I returned to Winn Falls and was tacken aback by the amount of re-growth.

Transect 3 - one year post mowing

I haven't completely entered and analyzed these data, but taking a quick peak, about 5 of the 44 left were dead. Three more were missing. And it looks like on average there was about 40cm of re-growth. Also, many of them had multiple basal stems. I suspect returning next year I will find many of these with fruit on them. Ultimately, these data may not make into my population model.  My sample size is very small (38 plants - lost 8 and gained 2 this year). But I think these data are still interesting. They make me wonder how affective a management strategy that involves cutting every couple of years can really be. Also, before the mowing, this field was a giant reservoir of Glossy Buckthorn seeds.  I can't help but think about the role this reservoir might play in the spread of buckthorn into nearby logging sites or down river.