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The Botany of Syrup

Categories: Trees

Any kid will tell you maple syrup is special, but how special? Is tapping a maple tree like putting a spigot in the trunk? And why maple?

In a wonderful book I’ve written about before by Nalini M. Nadkarni called “Between Earth and Sky-Our Intimate Connection to Trees” she writes of how botanists and tree physiologists have been looking at how sap is produced within maple in the last couple of decades. Like many things, the wild world of maple syrup seems like a freak chance, a perfect random combination of physiology.

A tree’s goal, aside from reproduction, is to feed itself-it’s tough being an autotroph, and a whole lot of work. Photosynthesis takes place all summer long, making sugars for respiration, growth, reproduction, and a little extra. This extra, in a sugar maple, gets stored as starches within the sapwood of the tree. The sapwood, as the name sounds, is the area of the trunk and branches where water and sugars move around, located within the first couple rings of the wood.

As my winter term class hopefully remembers, Sugar maple is one of our “live slow, die old” species of trees. These trees are more shade tolerant, in life for the long haul, and have the foresight to save extra sugar for lean times, such as the introduction of shade or competition. Other tree species, such as Poplar, live fast and die young, and burn through all their sugar like a hyper 3 old, just as prone to growth spurts as an Aspen in the spring.

Early spring brings sun, a little higher in the sky, and better able to warm. Cats in our house know this, moving away from the woodstove and into little patches of sunlight on soft surfaces. Trees know this too, as the sun warms the bark and the wood. The air may be below freezing, but tree surfaces and interiors could be well above freezing. Once the wood gets to be above 40 degrees, enzymes turn these stored starches into sugars, mostly sucrose, and the sugar is now within the sap. This explains the magical sugaring temperature of 40, any warmer and this process stops.

The other freak chance miracle of maple is getting the sap flowing out of the tree. Not all trees can do this. Water is moved throughout the xylem of the tree by capillary action and transpiration, meaning the leaves need to be on the tree for water to move very effectively. That  would ordinarily make for tough sugaring in March and April, except in Maple.

In maple trees the space around the wood fibers is filled with gas, not water like most plants. When the temperature drops, this gas contracts, making space for the sap laden with sugar in between the cells. So water can move upwards from the roots by capillary action without the benefit of transpiration from leaves. This water freezes at night between the cells.

The day brings warm temperatures, melting this ice and expanding the gas, forcing water down the branches into the stems and trunks of the tree. The taps put into tree trunks to collect sap pierce the xylem all this sap is moving through, and water flows down the tap into the bucket or plastic line.

Interested biology students should read another blog, The Botanist in the Kitchen, http://botanistinthekitchen.wordpress.com/2013/03/18/maple-syrup-mechanics/ , and a cool roadtrip would be the Proctor Maple Research Facility of my old school UVM.

 

Middlebury’s Elm Collection

Categories: Landscape, Trees

Among various tree geeks in New England Middlebury is well known for our Heritage Elm Collection. Elms, of course, naturally succomb to Dutch Elm Disease if we humans aren’t very proactive. We treat 28 old Elm trees, some of which are over 150 years old. I’ve written a couple new pages on them, one a general overview of all of the elms, one a brief primer on Dutch Elm disease and how we maintain the trees, and a final page on the history of the elm tree at Middlebury.

12-Elms

Elms have that classic umbrella shape, but can vary from specimen to specimen. We are fortunate to have trees in a wide variety of sizes and shapes, from the low spreading type like the Dog Elm behind Munroe (yes, we’ve named some of them), to the spectacular high and arching Field House elm. We also have been planting disease resistant varieties, such as Accolade Elm.

I remember a conversation with one of our seasonal employees several years ago, and we were discussing the difference between botany and horticulture. He cited the elm as a good example. Botanically, we will always have elm trees. They don’t die from Dutch elm disease until past their reproductive years, so they will always set seed and produce more young. And looking at them from a geological time perspective, eventually they will develop resistance, although that may be many millennia. Horticulture, though, is as much art as science, and as horticulturists we preserve some of the grandeur of an old elm, and we remember the dignity of the old shade tree as it was, even as we work towards bringing them back.

Tree Map Updated

Categories: Landscape

Having run inside, fleeing from the sub zero temperatures outside today, I spent the day updating our ArcGIS tree map with all the newly planted trees this year, as well as our removals. Seems like a good time to point towards the Campus Tree Map page, or go/treemap. The latest map contains all the trees we individually manage on campus, nearly 2500. Maybe if the cold spell lasts we’ll come up with a smartphone compatible tour…

Arbor Day, the film

Categories: Random Thoughts

When some friends from the Vermont Department of Forest, Parks and Recreation and the University of Vermont came to my winter term class to see our group project on Emerald Ash Borer, one of the things that impressed them the most was the diversity of experience in the classroom. We take it for granted at a liberal arts school, but to them it was quite novel to have Studio Art and Religion majors in the same classroom with Biology and Environmental Studies.

I’ve also discovered another delightful fact about teaching here at Middlebury-the sometimes painful truth that all of the students are more intelligent and creative than I could ever hope to be. It’s a great feeling to have your simple little course on trees extended into other work across campus, in liberal art ways you would have never thought.

So in that spirit, I want you all to watch Arbor Day, the movie. Created by the incredibly talented Joanie Thompson for Sight and Sound I in the Department of Film and Media Culture, it made my whole day. As I’m sure happens often at Middlebury, the teacher becomes the student.

Arbor Day from Joanie Thompson on Vimeo.

 

Arbor Day 2013

Categories: Landscape, Trees

It’s been a gorgeous spring, and we’re celebrating with a huge Arbor Day celebration. Plan on joining us May 14th, details below. But in the meantime…

love a tree? share the love. send us photos, poems, and other art about your favorite campus tree. Submit a photo, or post on twitter with #middarborday. submit by may 10 to have your tree featured in the arbor day tree-k race! Either go twitter (@middland) or send to tparsons (at) middlebury.edu to submit. Prizes, fame, fortune, and good tree karma await. And the winning trees will become the basis of the second annual Tree-K race around campus (run 5-K,, and learn the names of 5 of the trees along the route to win) A kid’s race will be held as well. Winners receive gift certificates to the Grille.

The days events will be as follows:

Campus Tree Tour-join us for a walk around campus and learn about some of our woody friends. The tour starts at the McCullough Plaza at 2 PM, and wends its way through campus until about 3:30, when we will end up north of Battell Hall, where we-

Plant a Tree- a whole bunch of trees will be awaiting your tender loving care to be planted north of Battell Hall and in between Allen and Wright Theater. If you’ve never planted a tree this is something you should do-it will still be here for all of your reunions, like the rest of your old friends you’re eagerly awaiting to see. Afterwords, you can run or watch the-

Tree K Race-run about a 5-K loop around campus to all the various favorite trees nominated by the Middlebury campus community. Winners will receive prizes, and all kids will as well. Not too strenuous, as you’ll need to save strength for-

Food, music, and ice cream-We’ll be on the Atwater plaza, with a cookout by Grille Catering using local foods, ice cream, and listen to music by Will Cuneo and Rita Pfeiffer. Enjoy the sunshine for an hour or two before heading back inside to study for finals. A huge thank you to the Environmental Council for funding us!

So spread the word, let your neighbors know, and come celebrate our campus forest.

My Latest Heartbreak

Categories: Landscape

No, not the song by the 22-20′s.

The plant vandalism on campus continues. We’re on year four, and I’ve been trying to document all the cases. The tally stands at 62 incidents in the last four years, 10 in 2009-2010, 25 in 2010-2011, 9 in 2011-2012, and 18 so far this school year.

Will Henriques wrote an excellent article for The Middlebury Campus on our spate of tree and  plant vandalism, after interviewing both myself and Brian Marland, a student in my winter term course who wrote a term paper on tree vandalism.  The thrust of Brian’s paper was how plant vandalism is an inherently violent act, and how this is more than likely related to alcohol consumption. Not even consumption by the vandals. Studies he found show an increase in violent tendencies by people not even drinking, but merely in the presence of alcohol or alcohol advertising. Brian writes, “aggression is no longer viewed as an unwanted result of drinking, but instead is seen as an expected condition.  Therefore, students may be committing vandalism in order to meet these expectations and produce a reputation among their peers.  When surrounded by a drinking culture, these expectations of aggression may fuel behavior that would not occur otherwise among these college students…While living in an environment where alcohol consumption on the weekends is common such as a dorm, a college student does not even need to consume alcohol to be subject to the aggressive thoughts and behaviors that may follow alcohol cues such as a beer bottle.  This revelation is instrumental in understanding the acts of tree vandalism that plague the Middlebury College campus.  After drinking, many students travel in groups to parties in other locations, and even if a person in this group had not been drinking, their behavior will still be subject to aggressiveness from exposure to alcohol cues.  They will be much less likely to interfere with or report senseless acts of vandalism in this heightened state of aggression.  Therefore, in an environment of alcohol consumption on a college campus, all students exposed to the environment may be suspect to increased aggression.”

I’ve written about the violence against the trees in the past, and we continue to see the same acts again this school year. The classic example would be an elm tree planted 2 years ago for the Atwater landscape project, rocked back and forth, and the 300 lb. root ball pulled up out of the ground and left on top for an entire weekend.

Elm Tree at Atwater

Elm Tree at Atwater

Sadly, this wasn’t the only tree torn from the ground this year-two more that were planted last spring were pulled during winter term.

As Will’s article alluded to, and Brian summarized well in his paper, the damage seems to be focused not necessarily around party locations (little damage is seen in Ridgeline, for example), but seems to be on pathways to and from these locations. I recently mapped the locations of the incidents for the last four years, and have included it below.

Tree Vandalism 2009-2013 Click for larger size

Tree Vandalism 2009-2013
Click for larger size

I continue to struggle with solutions. Some communities post signs next to the damage. I hestitate, thinking about how within the next year I’ll be going on school tours as a parent. Surely the article in the Campus is a great start, as will be our annual tree planting for Arbor Day (May 14, mark your calendars now). We’re a small community, we have to take care of each other, and that would include our campus forest as well.

Pruning 101

Categories: Trees

Students that have taken my class will probably remember how disdainful I was about (well, lots of things, but in this case) books on pruning. They probably still line bookstore walls, but I avert my eyes fastidiously, so don’t quote me. Large tomes on pruning trees and shrubs, each plant type seeming its own chapter. How do I prune a lilac? A maple? A ninebark?
The books are worthless. A little plant biology under your belt, some tools, and we’ll have you all set to go in no time at all.

Timing

George Aiken famously said the best time to prune was “whenever the saw is sharp”. He’s close to correct. There is no bad time to prune, only better times. Most orchards are pruned in the winter. Why? Long winter, nice to get outside. We prune our shade trees on campus during the winter as well, and for the same reason. The only time I would not recommend pruning is early spring, as the buds are swelling and starting to pop open. Trees and shrubs are working so hard this time of year, pushing new growth without their leaves ready to replenish themselves by photosynthesis, so they are using all their stored energy, and could possibly be weaker and less able to recover from pruning. That being said, if that’s the time you’ve got, then so be it.The evil pruning books will also go on about timing, giving large charts about when to prune various flowering trees and shrubs. One rule of thumb will cover all that, though. Prune immediately after flowering. Spring flowering things, like lilacs and crabapples, have set their flower buds last year, so a winter pruning will cut them off before they had a chance to flower. Summer and fall shrubs will probably flower on new wood, so pruning them with the lilacs in June will probably cut those buds off as well. After flowering covers just about everything.

Tools

Anything you got that’s sharp will be just fine. I prefer Felco pruners (http://www.amazon.com/s/ref=nb_sb_noss_1?url=search-alias%3Daps&field-keywords=felco+pruner) and Silky handsaws (http://www.sherrilltree.com/Professional-Gear/Silky-Saws) but this is what I do, so I’ll spend a little more on something that cuts well and will last. Try and avoid what are called Anvil pruners, the kind with the blade that stops on a flat piece of metal, as opposed to moving past the bottom piece (bypass pruners). The flat piece of metal crushes the live wood around the cut, possibly injuring the branch protection zone.
If you feel like you need rope to climb a tree, or a chainsaw to prune, back away slowly. You’re reading the wrong post. By all means don’t use a chainsaw on a ladder or in a tree. Spend some time on You Tube if you don’t believe me.

Technique

The hardest thing to explain is the necessity of a plan. Why are you pruning this plant? Is it in the way? Funny looking? Too tall? Most plants really don’t need to be pruned, we just think they do. Probably because we planted them in the wrong place, or they have a hazardous condition we would like to remedy. But before hacking away on the poor thing, you owe the plant a couple seconds of your time to stand back and make a plan. And step back often while pruning, checking yourself.
Starting in, remember the 3 D’s, Dead, Diseased, and Dumb. Start by pruning out all the dead wood from the plant. It’s dead, the plant doesn’t need it. (Maybe the ecosystem does, but that’s another blog post.) Also, this prevents you from making a bad mistake a little later on. I’ve pruned much live wood out of a tree to free up a beautiful branch in a direction and location I liked, to later find that branch was actually dead. Once you’ve gotten everything dead, start looking for diseased wood. Little white fishscale fungus, bark peeling away, there are all sorts of little clues that tells you that branch is probably on the way out and will join the ranks of deadwood shortly. Like truly dead wood, no sense to save it, or to count on it when pruning for structure.
2 D’s down, now the fun one. It won’t take a PhD in plant biology to recognize that plants aren’t the most intelligent creatures out there. Sometimes a branch will grow straight down. Cut it. Sometimes a branch will grow right into its neighbor. Cut it. Look for branches that are crossing, rubbing, growing in the wrong direction, growing parallel to one another, or anything else that just plain looks dumb, and get rid of it.
Now that you’ve gotten everything that shouldn’t be there, you can start to prune for structure. That’s a little more than an intro blog post will cover, but here’s a good start. For trees, read http://na.fs.fed.us/spfo/pubs/howtos/ht_prune/htprune-rev-2012-screen.pdf . Pay particular attention to the section on where to make a proper pruning cut. For shrubs, a good basic rule would be to remove any large woody stems-plants bloom and look better with young, vigorous wood. Like lilacs-every year I like to take out a stem or two that are larger than 2”, leaving the younger thinner ones. This has the advantage of keeping the plant a little smaller (so you can reach the blooms to cut them for a vase), a little less gangly, and a little more manageable.
Our department will be pruning trees in the library quad for the next month. Feel free to stop and ask questions.

Cultivating Hope, Wisdom, Compassion, and a Tree

Categories: Trees

Nature can teach us many things. Life, death, love. And Hope, Wisdom, and Compassion. How appropriate the 14th Dalai Lama uses ‘cultivating’, the act of promoting growth, to describe his wish for the dissemination of his main tenants for the human race to strive for.

Sogyal Rinpoche, the Buddist author of the Tibetan Book of Living and Dying, writes of trees:

Think of a tree. When you think of a tree, you tend to think of a distinctly defined object. But when you look at it more closely, you will see that it has no independent existence. When you contemplate it, you will find that it dissolves into an extremely subtle net of relationships that stretch across the universe. The rain that falls on its leaves, the wind that sways it, the soil that nourishes and sustains it all the seasons form part of the tree. As you think about the tree more and more you will discover that everything in the universe helps make the tree what it is; that it cannot be isolated from anything else and at every moment its nature is subtly changing.

A Bur Oak is planted next to the Garden of the Seasons just south of the main library, waiting to be blessed by His Holiness the Dalai Lama. Think about this tree, as it grows tall and wide, its roots spreading far across the quad joining its companions, and be reminded that like a tree, we all depend upon each other as well: we all share a subtle net of relationships. Let the small oak show our hope, our faith in growth and long life, as our grandchildren will see the large tree. And let it teach us wisdom, like the timeless ‘wise old oak’ of our childhood stories, and learn from it compassion, as no tree stands alone.

Bur Oak by the Garden of the Seasons

Watering

Categories: Landscape

Pick up any plant biology book, and they consistently list the three macro nutrients all plants need as N, P, and K, the chemical symbols for Nitrogen, Potassium, and Phosphorus. But really, what we share with plants is a need for ‘macro’ macro nutrients, something so profoundly necessary that the books don’t even feel the need to list them, and they form the backbone of all life. We’re talking about C, H, and O, or Carbon, Hydrogen, and Oxygen.

The carbon and the oxygen are easy, the plants are getting that in the air we breathe. It’s the Hydrogen that’s been stressing me out lately. Plants obtain it solely from water, through photosynthesis. I always remember my snide remarks in the retail garden center world, when a customer would ask me what kind of fertilizer to buy with their new purchases. For the most part, I’d tell them the single greatest thing they could do would be to water.

How much? It’s a good question with no real definitive answer. I remember from who knows where that gardens in the northeast need about 1/2″ of rain a week in the growing season, and an article on strawberry production I found says about the same (actually .63″). Trees need quite a bit more, though, as they have much more extensive roots throughout the soil horizon. Plan on 2″ of rain a week. I found a handy online calculator to do the math, but here’s a quick answer. A newly planted tree with about a 2″ trunk, should have a 5′ x 5′ zone watered around it, so that’s about 30 gallons, pretending to be a 2″ rain.

Sounds a little high, but the wild and woolly world of plants is never easy.  Last year we were averaging 4″ of rain a month, and we didn’t have to do any supplemental watering. On cloudy days plants don’t transpire, or lose water, at as great a clip, so maybe last year it was fine.

Or not. We’re running around like chickens with our heads cut off right now, watering every tree we’ve planted for the last 3 years. (that’s a lot) All of our recently planted trees are showing drought stress, and I’m wondering if I hadn’t watered enough in the last 2 wet years to well establish the trees. When watering, it is best to water a lot all at once, so that the roots have ample moisture and can grow long and deep. Too little water, and the tree keeps its roots near the surface, where the water is, and this makes it less drought resistant in the long run.

Gator Bags for Watering

We water all trees with 40-50 gallons of water about every 2 weeks. We use two gator bags zipped together, and they drain over the course of about a day. We hand water any tree we missed, and then gator bag it. In this heat and drought, I’d like to water weekly, but I’ve been checking the ground around the trees, and I think we’re keeping up.

Another good trick I learned once when hand watering is to watch the ground as it absorbs water from the hose. I think this is the one of the Eliot Coleman gardening books, but I loaned my copy out and now it’s gone. Once the ground starts to get saturated, the top gets glossy. Take the hose off that spot, and the glossiness will disappear. If you can count to 3 before the glossiness is gone, the ground is moist enough.

Drought stress symptoms in Birch

identifying drought stress in plants can be tricky, especially in herbaceous plants like annuals and perennials. Woody plants are easier. The inner leaves of the tree turn yellow and fall off. I find this remarkable. It isn’t like trees have brains, but here they are smart enough to drop the inner, less efficient leaves, to conserve its precious water for the maximally producing outer leaves. By the time your plants are showing symptoms of drought, obviously much damage is done. Plants are pretty hardy, so even with serious problems the tree will probably be fine.

2011′s Tree Karma Score

Categories: Trees

Applying for certification for Tree Campus involves a very enjoyable day of taking stock of the previous year. They ask about tree plantings, removals, dollars spent, volunteer hours, and community service projects. During a terribly boring snowless winter, it was nice to sit down and revel in our accomplishments during the previous growing season.

2011 was a banner year for tree planting. With the Forest renovation, the CFA renovation, our normal tree planting program, and the Atwater Turf Battle construction, Middlebury planted nearly 100 trees on campus this year.

We’ve had to remove some too. Storms and hazard tree removals are the most common culprits, although occasionally construction takes it’s toll as well. (It’s this reason I get lots of input from many people before planting, including managers in Facilities and the Master Plan Implementation Committee.) This year 22 trees have been removed.

So our Tree Karma score for 2011 is a very healthy 4 1/2 trees planted for every one removed.

Informally we try to plant 2 trees for every one removed. Our six year karma average is 3.8 trees planted for each removed. I got asked the other day what my favorite trees planted this year were, and thought it was either the Arbor Day planting, the large trees planted around Ross Commons, or maybe the rare trees planted to the west of Munroe, including a Stewartia, a variegated Tulip tree, and a rare yellow Magnolia. Or maybe the disease resistant elm in Adirondack Circle. But how can I single out one child over another?

We’re planting this spring too, mostly locally grown trees, in various locations all over campus. There is a method to our madness, we don’t just randomly plunk trees down all willy-nilly. One example is this year’s Arbor Day planting, just north of Battell. That awkward little triangle of grass lets Battell Beach lose it’s structure on that corner, and the space of the beach bleeds into the quad in front of La Chateau. The trees planted there will form a wall of sorts, segregating two spaces, and probably extending the usable lounging space of the edge of the beach.

(Not making any sense, am I? The next good beach day, go look at where people are laying out on Battell Beach. The southeast corner, down by Forest hall, along the southern edge, near the Forest hall sidewalk and some pretty spectacular ash and beech trees, or along the base of the slope that heads up to Pearson hall. Think about all those spaces. Psycologically, they are all protected–your back is up against a building, or a line of trees, or a slope. The northeast corner, near Chateau? No wall, no back, just open space across the sidewalk. Almost no one sits there, preferring instead to be near the line of spruces on the north end of the beach.)

Other places trees get planted are near trees that are dying, albiet slowly. I don’t like removing trees, and it makes me feel better to know when I do remove a tree I’ve already got it’s replacement planted and well established nearby. Look for some new trees near the Davis Family Library for this reason.

And by all means, join us today at 1 to plant some more-north of Battell Hall. We’ll allow you to get dirty.