The Great BRF Tree Project: Shotgun Sampling

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Dr. Schuster taking aim

Today, I collected leaf samples from six maple trees using a shotgun.

Well, technically, I didn’t use the shotgun.  Dr. William Schuster, the director of Black Rock Forest and an experienced hunter with all of the appropriate certifications, used the shotgun.  But the trees he shot at were trees I had marked a couple of days earlier, and the branches he shot down were branches from which I clipped leaves to test as part of my project.

Let me back up a bit.  In the 1980s and 90s, ecologists started to take an interest in the canopies of tall trees.  They wanted to delve into the canopies of rainforests and examine the complex communities in the tops of redwoods. This interest would develop into the field of canopy research, a collaboration between biologists studying ecosystems and foresters with a deep working understanding of the trees under study.

How does one do research at the top of a tree hundreds of feet tall?  Early methods, which included towers built in the middle of the forest and adapted weather balloons, were expensive at best and hazardous at worst.  Eventually, scientists improved upon these methods; today, tools such as a lift truck more commonly seen at construction sites carry tree ecologists high into the air.  (Black Rock has a lift truck, which I got to ride when a graduate student was using it to track photosynthesis in the canopies of spruce trees last summer.  It was more exciting than most amusement park rides.)

But then, what if you want to study leaves, bark, flowers, fungi, or anything else that might be growing at the top of a tree, but don’t have the time and funds to build a tower or borrow a lift truck?  What if, just to pick a random example, you’re an undergrad student on a limited budget who needs to collect leaf samples from red maple trees in a specific part of Black Rock Forest, but all of the trees in that area are too tall to reach on your own (even with your trusty friend the pole saw)?

In that case, a shotgun – responsibly used – may be a valuable new friend.  One simply aims the gun a high branch and fires a bullet large enough to knock the branch down to the ground.  The technique is much easier explained than performed, though; it’s challenging to aim at thin branches over 30 feet in the air, and often takes several trials to not only hit the desired branch, but also hit it at an angle that will bring it down.  Dr. Schuster explained to me that the best shotguns for this method are those that shoot a case full of large BBs, metal ball projectiles, in a close pattern.  The close proximity of these bullets increases a shooter’s chance of actually knocking down a branch, because one of the BBs will still hit even if the shooter’s aim is slightly off.

Ecologists working at Black Rock Forest have used this method for years, even since before the Consortium was founded.  The forest actually owns its own shotgun and BBs; the gun is kept in a secure location and locked, so that only specific staffers who have received training can use it.  Researchers are also careful to consider their environment when shooting branches, by picking up shot casings rather than leaving them to litter the forest.  I have helped with this part of the process twice now (Dr. Schuster also shot a few branches for me a couple of weeks ago in a different part of the forest), and am becoming adept at spotting the bright red cases amid the forest debris.

Here’s what the process looks like in a short clip; Dr. Schuster demonstrates the trial and error of aiming for high branches (warning for a loud noise):

But sometimes, a researcher can shoot down a branch on their first try, as Dr. Schuster does here (again, warning for a loud noise):

Shotgun sampling is an exciting means of collecting leaf samples – it’s certainly much louder than my usual clippers and pole saw method.  Yet with great branch height comes great responsibility.  As Dr. Schuster and I returned to the Black Rock science center after shooting branches, he realized that his car was low on gas, so he instead drove to the edge of the forest and we waited for another staffer to help us out.  While we waited, he turned on the local radio station – which was playing live coverage of the shooting that occurred this afternoon at the office of a local newspaper in Annapolis, Maryland.  In Dr. Schuster’s hands, a shotgun is a tool for science, but in another person’s hands, this tool quickly becomes a deadly weapon.

We sat in silence for at least half an hour, listening to the broadcast.  I imagined myself in that Annapolis newsroom.  I imagined a shooter invading a Bwog pitch meeting.  I imagined a hundred other scenarios until the shotgun in the back of the car felt less like a fun toy and more like a heavy weight, pulling me down beneath the dirt.

Sometimes, just because something can be a useful tool for science doesn’t mean it should be.  If stricter firearm regulations were imposed, ecologists could always find other ways of collecting branches from tree canopies.  The Annapolis journalists can’t recover so easily.

Photo and videos via Betsy Ladyzhets

The Great BRF Tree Project: My Best Friend the Pole Saw

Picture this: you’re out in the woods.  You find a maple tree.  It’s a species you can confidently identify, it’s not too far from the path, and it has clean, healthy leaves.  Or in other words, it’s perfect for clipping off a branch for leaf samples.  There’s just one problem… all the branches are at least 10 feet off the ground.

This dilemma is pretty frequent in my line of field work.  Trees are tall.  No shit, Sherlock, you’re probably thinking.  And, like, I’m aware that, intellectually, we all know that trees are tall.  But this knowledge doesn’t really hit on a physical level until you’re standing at the base of a huge oak, staring up at branches that you’d never be able to reach even if you were a champion high jumper.  And that’s just the lowest branches!  The peaks of some older trees at Black Rock Forest are hundreds of feet in the air.  Walking on forest trails sometimes feels like walking through New York City, except much cleaner and quieter – I’m always looking up.

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My good good pole saw

There is an easy solution to this dilemma, however.  To collect leaves from above my arms’ length, Black Rock Forest has kindly allowed me to borrow a pole saw during my weeks here.  A pole saw, as I’ve described in previous posts, is basically a long saw on the end of a pole.  Gardeners use it for pruning trees and large shrubs, and plant biologists use it for collecting leaf samples from branches too high for them to reach on their own.

My best friend pole saw (as I’ve affectionately taken to calling her) is a fairly simple model.  She’s about six feet long in its usual state, and extends to twelve feet when I pull out the extendable piece.  When I lift the instrument into the air, my own height adds on a couple more feet; thus, with the saw, my range is a total of about fifteen feet.  That’s over double the height I could reach on my own.

To operate my pole saw, I stand directly beneath a branch I’d like to cut and position the pole perpendicular to that branch.  I adjust the pole until the saw part (mounted on top) is settled around the branch.  Then, I pull down on the rope attached to the saw, causing it to swing down and chop the branch off.  It’s basically thrusting a knife into the air, positioning it in a specific spot, and then pulling it down to cut.  The technique takes a good sense of balance (which I don’t have) and a whole lot of patience (which I definitely don’t have), but I’m getting better with practice!

It’s impossible to fully capture this technique with a written description, but I think this video might help you get a better idea:

(Big thanks to Ellery for taking this video!)

I’m also getting pretty attached to this pole saw, as you might be able to tell by the story I told at the beginning of the video.  Not only is she an invaluable tool in my field work, she’s also a companion on my long hikes through the forest.  The saw doubles as a walking stick, an instrument for testing whether the ground ahead of me is stable, and an imaginary conversation partner.  I’ve gotten into the habit of apologizing to her when I lose balance and let the pole swing out abruptly or let the blade hit the ground.

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My research mentor operating a 30 foot pole saw

My pole saw is a good friend.  She may not be as tall or as sturdy as other pole saws, and she may not be able to reach high branches like a lift truck or the shotgun method (topics for future posts.)  She may be difficult to balance, and she might get heavy on long walks, and she might sometimes get stuck in a spruce tree and give me ten minutes of extreme stress.  But she’s always ready for an adventure – and what more could you ask from a friend?

Photos and video via Betsy Ladyzhets

The Great BRF Tree Project: Tree Identification 101

Update, September 26, 2018: This post has been adapted into an article on BRF’s website, “The Forest in Fall: Tree Identification and Leaf Color.”

As I’ve said on this blog before, half of my work in gathering samples is finding the right trees.  Such a task may sound easy.  You just go into the woods, you pick out all the maples, and you’re out, right?  Wrong.  There are 455 species of tree native to eastern North America listed in my Peterson Field Guide, 65 of which have been documented at Black Rock.  For every tree on my list of species to collect, there are at least two or three other trees for which I could easily confuse it, on the basis of probability alone.  And that’s not even talking about the numerous shrubs (weedy and established) that I’ve added to my species list this year.

Finding my desired trees in this massive forest is like trying to find a green needle in a stack of other green needles.  The needle I’m looking for might be a slightly different shade than the other needles, or it might be slightly thinner, or slightly sharper.  But it also might be slightly wider, or slightly duller, if it’s younger or has lived in a different part of the forest.  Or it might be torn up by insects.  Or it might be just imperceptibly different from all the other needles, but is on a branch ten feet high where I can only get a closer look after wrangling my pole saw for several minutes.

All in all, tree identification takes a lot of practice and a lot of trial and error.  I’m far from an expert, but I’ve had enough concentrated practice that I trust my skills at least with common species.  During several weeks of working on this project last summer and two weeks of getting back into it this summer, I’ve used information from the Peterson field guide, online resources, and the experienced BRF staff to identify over 20 species on my own.  (Although I usually check with staff members when I’m unsure about something.)

Here are the primary markers I use for determining the identity of a tree or shrub.

Location:

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Bear oak and other high-elevation shrub species at the peak of Black Rock Mountain

A plant, like any organism, occupies a specific niche – an ecological term that describes a set of environmental conditions specific to that organism which give it a place in the larger ecosystem.  Niches can include what resources the organism uses, what it eats, when it reproduces, or where it lives.  That last category is often useful in identifying trees, as I can use my knowledge about which species live in which areas of the forest to figure out what I might be looking at.

For example: bear oak, a shrub in the oak (Fagaceae) family, is only found at high elevations, mostly on mountain tops.  Thus, even if I see a plant with similar leaves, if it’s not growing on a high point in rocky soil, I won’t expect it to be bear oak – it’s more likely a different kind of shrub.  Similarly, eastern cottonwood is an invasive species that only successfully grows at Black Rock Forest in highway regions where the native forest has been cut away.  Thus, even if I see a plant with similar leaves, if it’s not growing on the side of a large road, I won’t expect it to be eastern cottonwood.

Leaf shape:

Leaf shape is my go-to identifier for most trees.  The leaves of many species I look for have characteristic shapes: they’re rounded or pointed, simple or compound, smooth-edged or jagged.  This identifier is perhaps most useful for established species that I see often, such as the oak and maple families; trees in both families have leaf shapes that appear similar from a distance, but are distinctive up close.

 

Although red maple and sugar maple have similar leaf shapes, red maple (left; via Evelyn Fitzgerald // Flickr) has rounder, more jagged leaves while sugar maple (right; via Dcoetzee // Wikicommons) has more pointed leaves.

 

Red oak, chestnut oak, and black oak also have similar leaf shapes.  But red oak (top left; via Angela Huster // Wikicommons) has more divided leaves with sharp individual points, while chestnut oak (bottom left; via Bruce Kirchoff // Wikicommons) has leaves with rounded edges and black oak (right; via yours truly) has fewer and deeper divisions.  Black oak can also be identified by its darker-colored bark.

Leaf texture:

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Slippery elm leaf (via Kristine Paulus // Flickr)

When leaves of different species have similar shapes, another useful means of identification is their texture.  This can be a difficult quality to evaluate, as I have to grab onto a few leaves from a tree (sometimes clipping them from a high branch) to tell if they are leathery, smooth, or soft.

For example: black gum has a similar leaf shape (rounded with one point at the end, no jagged edges) to that of ash trees, but this species’ leaves have a distinctive, leathery texture.  Slippery elm also has a distinct texture: rubbing the leaves of this species between your fingers feels like rubbing sandpaper.  Even the texture isn’t enough to confidently identify slippery elm, though, as I discovered today while talking with Katie, BRF’s research manager.  Hop hornbeam and black birch, both native BRF tree species, have leaves that are practically identical to those of slippery elm – and hop hornbeam even has a very similar texture!  Even though the three trees aren’t even in the same family!

Bark:

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American beech – check out that smooth, dark gray bark

Bark can be a tricky identifier, because depictions in field guides and other resources usually describe the bark of older, mature trees while I often look at younger saplings in the field.  Still, by honing in on older sections of a tree (usually the trunk near its base), I can sometimes solve debates about its identity based on this outer casing.

The case of slippery elm v. hop hornbeam, for example, falls to bark: slippery elm has rough, intensely textured bark, while hop hornbeam has more regular, peeling bark.  (Black birch, another similar species, has smooth bark with horizontal stripes.)  After closely re-examining some trees from which I’d taken branches last week, believing they were slippery elm, I have now realized they’re actually hop hornbeam, based on this test.  Damn.

Another tree that can be easily identified by bark is American beech, another member of the Fagaceae family.  American beech has smooth, gray bark that can appear almost shiny compared to the other trunks in a forest of oaks and maples.

Flowers:

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Mountain laurel blooming at the peak of Honey Hill trail

Flowers are useful markers when I look at shrubs.  Although it’s still early in the season and many plants aren’t yet blooming, for those that are, I can spot a particular species from many feet away by looking for specific flower shapes and colors.

Today, for example, I looked for flowers while searching for six samples of mapleleaf viburnum, a shrub with leaves similar to those of maple and clusters of unique white flowers.  I found it along road sides and near one of Black Rock’s reservoirs.

Another distinct flower is that of mountain laurel, which has recently begun to bloom in sunnier spots – on mountain peaks and around bodies of water.  This shrub has gorgeous white and pink flowers that are unforgettable once you clip a few samples of the plant’s branches.  (The flowers got absolutely everywhere in the lab when I processed mountain laurel samples yesterday, though.)

Practice, practice, practice!

Identification is incredibly challenging, and I get it wrong a lot of the time.  But I’m practicing in every way I can.  I point out species to myself when I hike around Black Rock even when I’m not specifically out to look for samples.  I bring small branches of species that I don’t recognize back to the Science Center and ask staffers if anyone knows what they are.  I hold onto small samples and stick them in my pockets for reference when I go out collecting.  After a couple more weeks at Black Rock, I’m hopeful that I’ll be – well, still very far from expert status, but at least able to distinguish between all the different oaks and maples on my own.

All photos via Betsy Ladyzhets unless otherwise specified

The Great BRF Tree Project: What’s in my Backpack?

Did you know that there’s a shrub relative of roses that has thorns on the underside of its leaves?  I learned this today while cutting the leaves off of a couple of branches of that very species.  Or, I should say, attempting to cut the leaves off… because the leaves bit back.

There’s a lot of “biting back” in my field work, from thorny branches poking me as I collect leaves, to bushes tripping me up as I venture through off-trail parts of the woods, to clippers in the back pocket of my work jeans literally biting into my back.  But experience has taught me to prepare for it as much as I can, by bringing a full kit of science and non-science supplies when I go out looking for trees.  That brings me to this week’s research methods post: what’s in my backpack?

Here’s my backpack and all of its contents:

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Taken after I returned from collecting black gum this afternoon

  1. Peterson Field Guide to Eastern Trees.  A field guide is essentially a small, portable encyclopedia on a specific topic.  Field guides to plants (also called floras) tend to include two sections: plates, with drawings of different leaves side-to-side for species comparisons, and text descriptions, including details of each species’ general location, bark, flowers, and other identifying info.  I rely on this field guide religiously, especially if I’m looking for something I haven’t collected before (see: all the sticky notes on the side of the book marking off species I want to find).  But I use it in conjunction with other resources, such as photos from online encyclopedias, samples from Black Rock’s herbarium, and knowledge of the forest’s staff.
  2. Book of poetry by Allen Ginsberg.  There’s no scientific use to this one – I just carry it around in case I need a breather and want reading material.  I am an English nerd as well as a budding biologist, after all.  My all-time favorite poem, “Poem Rocket,” is in this book.
  3. My own notebook.  A good scientist would buy a new notebook to devote entirely to a project such as mine.  I am awful at compartmentalizing, however, so I just use the same notebook in which I write subway poems, fanfiction drafts, and other notes for recording tree data and observations.  Most of my sampling notes are taken on the Avenza app these days.  Still, I like to keep the paper notebook with me just in case (and it’s useful if I’m ever compelled to stop and write.)
  4. Water bottle.  This one is self-explanatory.  Gotta stay hydrated!
  5. Bug spray.  Ben, one of the forest maintenance staffers at Black Rock, always tells me that I shouldn’t wear bug spray.  “Just use unscented soap,” he says.  “You’ll earn the respect of the mosquitoes, and they’ll leave you alone.”  But I am a mere mortal, not a forest spirit like him.  And anyway, I seriously doubt I could find unscented conditioner that works for my hair type.
  6. Sunscreen and sunglasses.  I rarely use these because, between trails and going off-road, most of my work happens in the shade.  Plus, since I wear long pants and a hat when I’m searching for samples, the only body part vulnerable to sun is my shoulders and arms.  I keep them around nevertheless.  (Fun fact: my dad got these sunglasses at a conference; the orange parts read, “Big Data Finance.”)
  7. Black Rock Forest trail map.  Rarely used for actual navigation, now that I have the same map on my phone and can actively track my location on it using Avenza.  Rather, this map is very useful when I need a small, flat surface upon which to write a label.  And it would be very necessary if (god forbid) my phone ever died while I’m in the field.
  8. Trail snacks.  I usually venture out on sampling trips in late morning and plan to have lunch after I return to the Science Center.  But often, finding the trees I seek takes longer than I expect, and I need to refuel before starting to walk back.  My favorite trail snacks are apples, granola bars, and salted almonds (all of which keep well in the heat.)
  9. The backpack itself.  This drawstring bag doubles as a flat surface upon which I can place my phone while sampling – the phone needs to lie flat for a couple of minutes in order to get the most accurate GPS coordinates.  The bag is already showing some wear and tear, so I might have to switch it out in a couple of weeks.
  10. Backup clippers.  Mostly I use the larger clippers (#14) for clipping branches from smaller trees and shrubs that I can reach without the pole saw.  I like to have an extra pair on hand, though, in case I accidentally drop the main pair in a lake.
  11. Marking tape.  This tape is thin and adhesive – perfect for marking the branches I’ve collected, after I get them down from their source trees.  I write down a tree’s ID (something like “AR4” – “AR” for “Acer rubrum,” the species, and “4” for the sample number) on the tape, then tear it off and wrap it around the base of the branch.  This helps me keep track of all my samples on a given day, and match up my eventual envelopes full of leaves with my points on a map.
  12. Identification tape.  This tape, unlike the previous tape (#11), isn’t adhesive; rather, it’s a bright-colored, stretchy substance perfect for tying around the trunks of trees.  I label all of the trees from which I sample with their IDs, matching the IDs on the branch samples themselves.  This makes it possible for me to find the trees later, if I were to mess something up and need more leaves.  If a tree I’m sampling is thicker, I often need to stretch my arms all the way around it to tie the tape – a perfect excuse to hug the tree.
  13. Writing utensils.  It’s much easier to write on the tape in Sharpie, so the pen is more of a backup.  I keep the Sharpie in my front pocket when I’m collecting, which is convenient but incredibly uncomfortable when I need to take big steps to get around prickers or mud.
  14. Clippers.  These have the same purpose as my backup clippers (#10): snapping branches off of shrubs and smaller trees that I can reach with my own arm span.  These are my main pair, though, because they’re larger and sturdier.  They’re also the tool I can feel digging into my right back pocket whenever I take a step.  But it’s all for science, right?

And now, last but far from least, the tool that needs its own picture because it definitely doesn’t fit in my backpack…

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The pole saw!

The pole saw is my new best friend.  It helps me cut off high branches from tall trees, like oaks and maples, that I wouldn’t be able to reach on my own.  It’s several feet long when collapsed, and the saw can be extended to twice the length pictured here.  Using this thing is like getting a plate on a stick from a circus, adding five more feet to the stick, and then poking it up into a tree and trying to angle it so that I can cut off a branch.  I love the challenge, though.

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Backpack and pole saw out in the wild, next to one of the trees I sampled today

Together, all of these tools help me search out trees around Black Rock Forest, identify them as species that I want to collect, and cut off their branches to bring them back to my lab.  I need all of them to stay on track and keep organized, even if a couple of them do sometimes bite me in the butt.

All photos via Betsy (CC by-ND 4.0)