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.

After the storm

I'm lacking time to do a fuller post these days, which is sad because I have several ideas bouncing around my head. I'll try to make some time later this week. In the mean time, this is just a quick note to say that I'm very curious what, if any, the affect of Hurricane Sandy will be on my Long Island field plots. I finished this season's work in the UNH area about a week and a half ago, and was planning to visit Caleb Smith last week, but obviously that plan was changed. For now, Caleb Smith is closed to the public, so it may be some time before I can finish this year's work. I'll do a post once I collect this data. Everyone stay safe for now.

In the field with my wife

My wife is so awesome that she insisted on using two of her floating holidays to help me out in the field in my southern New Hampshire sites this past September. It was great to have Gina in the field for multiple reasons. First, not to get too cheesy, but I really enjoy hanging out with her.  Second, field work goes so much faster with another person. Third, it was interesting to get some new ideas about doing field work from someone who isn't as tied up in the project as myself.

Gina, ready to measure some plants!

One of the best ideas Gina had for me was to draw a rough map for each of my quadrats, showing the general position of each tagged plant in the plot.  At first, this seemed like an awful lot of work, but thinking about it a bit further, and failing to find a few of last seasons marked plants, made me reconsider.  If you have ever tried to find tagged plants you know that sometimes it's very hard.  A year's worth of debris has accumulated, often times hiding tags under a layer of compost.  Some researchers employ tricks and tools such as using a metal detector.  I have not gotten to this point - partly because I cant afford a metal detector.  So, lacking a metal detector, I'll dig around in the duff for upwards of 30 minutes looking for a single tag.  Here's what I imagine a quadrat map might look like.

An example of a 'quadrat map'

The numbers indicate the tag number for each plant.  Clumps of plants with sequential tags might be listed together with a general shape of the clump.  Distinguishing characteristics, such as the presence of a particularly large tree would be noted.  Etcetera.  I really like this idea, and I don't think it will take much time to sketch out such maps in the field when tagging plants.  Next season, as I prepare to make some of my sites longer term monitoring plots (i.e. places to go back to after I finish my PhD) I think I'll start making these quadrat maps.

Happy field workers at the end of the day!

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!

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.

On how I chose my samples - Part 2

So last I left off on the topic of choosing samples I was discussing how I realized that I really needed to have a good look around me and think about what I was trying to accomplish in order to help me come up with a sampling scheme.  And for the most part, that's just what I did.  During my field visits in the Summer and Fall of 2009, and even somewhat during field visits in 2010, I spent several hours standing in patches of Glossy Buckthorn thinking about how best to select plants to tag and follow.  Sometimes I would call my friend Adam (also studying plant ecology at the time) and bounce ideas off of him (or ask him to generate random numbers for me).  Sometimes I would call my wife and complain about the dense blackberry bushes, multi-flora rose, ticks, etc - ya know, sometimes you just need to whine a bit.

Here are a few of the standout observations that helped me develop my sampling scheme:

• Glossy buckthorn patches vary in density and I wanted to avoid over-representing plants in areas of high density or under-representing plants in areas of low density
• For the purposes of my study I want to follow individuals, therefore areas that are bare of Glossy buckthorn are not good places to look for plants to follow (yeah - this one is obvious)
• Glossy buckthorn grows in varying ecological conditions (under story, gaps, riparian zones, uplands, etc.) and my samples should come from as many of these conditions as is feasible
• The ecological conditions mentioned above are generally clumped. That is, the ecological conditions I'm interested in usually make up their own patch (e.g. a large patch of understory or wetland)

With these observations and thoughts in mind, I decide that the most important aspect of my sampling scheme should be that I select individual plants to follow across different plant densities and in different ecological conditions.  So here's the final sampling scheme I chose:

• Ecological conditions - I selected a specific combination of ecological conditions (e.g. upland-understory forest) and using a GPS outlined the borders of a Glossy buckthorn infestation within the bounds of the borders of the ecological condition.
• Individual plants - Once I had the border of an infestation, I selected 15 to 20 random points within these bounds where I set up 2x2m plots, or quadrats.  Within these plots, I tagged and measured all Glossy buckthorn plants that were taller than 10cm. Plants smaller than 10cm were considered saplings, which were sampled differently.

This type of sample scheme is essentially a stratified-random design, stratified across ecological condition and random within that condition.  So far I think it has worked out pretty well.

Random 2x2m plot in a large forest gap. Orange flags mark the corners of the quadrat.

Fieldwork, ESA, and Moving

The last few weeks have been filled with fieldwork in New Hampshire, travel to Portland, OR for the annual Ecological Society of America (ESA) meeting, and moving from our home out near Stony Brook to a new place in Nassau County (closer to NYC and to my wife's new job) - hence the lack of posts.  Here's a brief post concerning my experiences at the recent ESA meeting.

While in Portland I participated in some audiocasts with a group of friends and colleagues, during which we discussed some conference highlights.  At the end of each day (the meeting was four full days) we gathered and talked about one standout presentation we saw that day.  Give a listen to these audiocasts if you're curious a) what ecologists think and say about each others presentations, b) if you're curious what I thought were a few standout talks, and c) if you want a bit more than an hours worth of entertainment.  The audiocasts can be downloaded from my friend Gabe Yospin's website for our Monday, Wednesday, and (coming soon) Thursday sessions.  Gabe also did solo sessions on Sunday and Tuesday that are worth listening to.

This was my first ESA meeting and I must say, I was impressed.  ESA is a (relatively) large meeting, approximately 4,500 people this year.  There are more than twenty concurrent sessions at a time! Which means during any session there was usually more than one talk I wanted to see.  Also, the conference center was so large that if back-to-back sessions were on opposite ends of the center, it was almost impossible to see both talks in their entirety (had to leave one early and still showed up at the other late).    But these problems aside, I was definitely impressed and inspired by the science reported at this meeting.