Author Archives: Tim Parsons

An Early Fall

It’s not your imagination, the leaves are turning early this year. The reason will seem a little odd, but an understanding of a tree’s relation to time helps.

I feel for scientists that have trouble explaining the concept of time. We are lineal creatures, stuck watching time pass from one year to the next. As a horticulturist, my year goes from spring to spring. But anthropologists measure civilizations in centuries, not our ordinary years. How about geologists, counting back years by the billions. Most impressive, let’s talk about Astronomy. A light year-the time and distance it takes for a photon of light to travel. It’s called the speed of light for a reason.

Tree time moves differently. Trees do everything slowly-germinate, grow, mature, reproduce, even die. Some varieties live well within one of our short lifetimes, while others will live for generations. Time moves in fits and starts for a tree, on yearly cycles familiar to those in Agriculture. But they aren’t exactly lineal.

Remember last year? It was a growing season in a bitter drought, with no rain for most of the spring, all of summer, not breaking until late in the fall. It was hot, dry, and overall not very pleasant. I use our annual flowers we plant as a barometer, and the ones we planted around campus languished in the heat, and with the exception of some petunias none ever really amounted to much.

Our tree canopy looked OK though, and we had a nice fall. But this year, not so much. Maples are turning early, losing their already smaller than normal leaves about 4 weeks too soon. Oaks have been thin all year, with many dead twigs and branches. But it was a great growing season this year, with all flowers blooming non-stop since commencement. But not in tree time.

Sugar Maple by Battel-
August 30

Trees are about a year off, marking time in their own way. They leaf out and grow all season, but reach back to the previous year’s sugars and energy stored from the prior growing season. Last year’s food is this years energy. So the drought last year certainly affected the growth of trees, but on tree time it doesn’t show up until this year. Weakened roots and inadequate resources in twigs and stems are stunting growth this year, and trees are wearing out and starting to turn early. Trees live a dual year, growing in the previous year while stockpiling for the next.

Same Maple as Above-
September 18

Ordinarily in the early fall there are always a couple of trees starting to turn, and the easy answer is that they are weakened, stressed trees, our canary in the coal mine showing us underlying problems we might not have seen. Usually the Black maples east of Old Chapel turn fall color early, a problem of not only age but poor soil and compaction from living in a college quad for 200 years. This year, though, it is many, many trees. Primarily sugar maples, and mostly middle-aged trees, I’d guess 40-75 years old. In tree time for a maple you can think of them as 30-year olds facing a mid-life crisis with all the associated baggage. Primarily we’ve seen trees turning this year as ones in poor soil, either on ledge, or heavy clay. Above my house on Snake Mountain I see the canopy turning color, the relatively young forest showing it’s stress.

Snake Mountain, first Week of September

Younger, less mature trees are probably more in balance, and also flaunt vigorous and resilient root systems, while old, mature veterans had the massive underground roots to weather the (lack of) storms. Neither are showing the stress or are turning early.

It’s too soon to say what the fall will bring for color, but I’d sure like to see a little more rain soon, and a break in this mini heat spell we’re having. I do predict an early season, though, maybe longer if the oaks in the lower elevations can hang in there.

Arbor Day 2016

I’m not much of a writer, so I won’t bury the lede here-our annual Arbor Day celebration will be happening tomorrow, October 7, starting at 4:00. I’ll be giving one of my walking tree tours through campus, followed by a tree and rain garden planting about 5:30 or so. Cider and donuts provided. Here’s the events listing for a sneak preview-

Meet on the front porch of the Franklin Environmental Center (FEC) for the very popular Campus Tree Tour led by passionate Middlebury horticulturalist and tree expert Tim Parsons. This year, FEC is focusing on the theme Urban Innovations, Sustainable Solutions, which will include exploring connections between urban and rural. As part of the tour, Tim will explain why he manages our rural Vermont campus as an urban forest. Stick around after the tour for a tree planting, complete with hot cider and fresh local donuts. Bring your willingness to learn about and to get a little dirty.

And this is a sneak preview-

Black Maple turning for fall by Old Chapel

Black Maple turning for fall by Old Chapel

Anyway, where have I been and what am I thinking?

Anyone blogging in an academic setting probably knows the difficulty. I liken it to a lead weight between my shoulders. I know I should be posting more, but being surrounded in an environment filled with people much smarter than I means a blog post needs to be weighty, relevant, and not a stream of consciousness this is turning into. In short, a blog post is something that takes considerable inertia to start.

But start I shall. And, naturally, I’m starting with the landscape. Come on my tree walk, I’m picturing it as an “Envisioning Middlebury-Landscape Edition”, to piggyback off the excellent work the community conversations around this topic that are happening. Un-facilitated though, unless you count the trees. (I’ll show you how they are talking back to us.) Landscape is not static, and as we discuss the future of Middlebury let’s not forget the outdoor physical environment as well.

The Trees are Alright

Abnormal weather always has people worrying about their trees and shrubs in the yard, and this winter is anything but normal. It’s the warm temperatures that are troubling, and many people have come up to me asking if the trees are going to be OK, or if the warm temperatures mean they are going to start growing.

Surprisingly, it’s the opposite, but this winter is a long ways from being worrying.

All temperate climate plants go through a period called dormancy, a mandated winter rest. This is triggered in the fall by not only temperatures, but by day-length. As the days get shorter the plants go through chemical and physiological changes to prepare for below normal temperatures. Once dormant, the plant needs sustained cold (500-2000 hours below about 40 degrees) to break dormancy and get ready to grow again in the spring. So, if this winter were to have stayed above about 50 all winter long the plants wouldn’t have started to grow, but the opposite, would just sitting there doing nothing.

And this makes sense. I’m always amazed at how smart and resilient plants are. While this winter is fairly unusual in the sustained warmth, we do see warm spells most winters, and plants that would start to grow at the first blush of spring wouldn’t be around very long. Breaking dormancy requires not only warm temperatures, but increasing day-lengths, longer spells of sunshine to break their winter gloom.

What can hurt a plant is freezing temperatures once dormancy is overcome. In trees, this is seen as frost cracking, long vertical fissures in the bark caused by water freezing in the xylem after warming up and moving around in the daytime. (Look at the trunk of the Sycamore in the triangle in Wilson Terrace outside McCullough)

This adaption to day-length also explains why plants with a local background (called provenance) is best. Day-length varies by latitude, with greater variation seen in northern latitudes. Take a tree from Vermont, move it down to Georgia (poor thing), and it will stop growing mid summer, as the days are a northern fall-like short. What I see quite a bit more, though, is the opposite. Plants grown in a nursery down south and moved up north don’t know when to shut down and start dormancy, and are often growing late into the fall, with their leaves and twigs freezing, unprepared for winter.

And while I’ve got your attention, let me take care of one final question I’ve been getting. No, your lilacs aren’t ‘budding’. Many people are looking at their giant buds on the ends of the lilac twigs, and think they are swelling about ready to pop and start growing. They were actually that large this fall, you just were too busy looking at fall foliage. Fear not.

New Vandalism

Middlebury is ending the semester awash not only with hard discussions on stress and appropriation, but with a new surge of tree vandalism.

Four trees have been vandalized in the last four days. Three this past weekend, 1 pulled up out of the ground by Battell, one by HMKL pulled up and dragged to the front door, and one snapped at the base, only 20’ from a dorm.

Dawn Redwood snapped at base

Trunk of the Dawn redwood

Then two nights ago a memorial tree was rocked back and forth, unsuccessfully broken off, so instead all the branches were snapped off, and the top severed and left on the lawn. This is a new on our campus, as we’ve never had a memorial tree killed before.

2015-12-09 13.08.06

Don’t think of it as vandalism, however, think of what is happening as aggression and violence. Vandalism is breaking off random branches here and there; violence is taking a well-established tree with a 3” trunk at rocking it back and forth for probably ten minutes until it snaps and breaks at the base. A former student wrote an entire term paper on tree vandalism, and told of the link of alcohol fueled aggression and violence against trees.

But, like many problems here on campus, who dares speak up? I’d certainly be nervous to confront someone in the act, and I carry chainsaws around for a living. I think back to my time on community council last year, with long discussions led by Ben Bogin on a Social Honor Code, not just an academic one. Read William and Mary’s code, or Haverford’s, with their ‘Confrontation’ philosophy, as difficult and engaging as President Patton’s wish for more and better arguments.

So maybe our department no longer plants smaller trees, as the smaller size seems to encourage vandalism.  The field house, for example, was planted in 3” trees, and they would be nearly impossible to pull out of the ground. The problem with that, like many problems we face this semester, is the concept of resiliency.

Like people, trees and forests do better in large, diverse groups. Diversity brings resiliency- look to the lessons of Dutch elm disease when many, many towns lost nearly all of their shade, or look to our future when Emerald Ash Borer moves into Vermont and destroys all our ash trees, almost 15% of all trees on campus. We are diverse in tree species, so 15% is a hit, albeit an unpleasant hit that we can suffer through.

But only if we keep planting our forest without ceasing, and keep the goal of diversity. The nursery industry in Vermont doesn’t have a big diverse selection in large trees, so we plant smaller unusual trees in addition to the larger ones. Smaller trees are also easier to plant, and cheaper, so we can plant more trees in a year, and come in many different species, much more than basic maple, oak, and honeylocust. It’s these small trees, however, that keep getting vandalized, snapped, and pulled up out of the ground.

Our campus forest is losing resiliency, and to be honest, so am I.

Tree Tour and Planting Wednesday

I’m hosting a tree tour and tree planting for our fall Arbor Day celebration this Wednesday at 4:30. It’s part of the 50 Years of Environmental Education & Leadership at Middlebury celebration (view the whole schedule here). We’ll be leaving from the front porch of Franklin Environmental Center (Hillcrest), wandering around wherever my feet and your questions take me, and ending up back at Hillcrest about 5:30 to plant 3 oak trees on the corner.

The oaks are coming from Miller Hill Farm in Sudbury, and are a mix of Red and Bur Oak. We’re replacing two blue spruce that died in that location, and these will be hardy long lived street trees. Another Sugar maple is dying nearby (not a great street tree, by the way), so the oaks are particularly fortuitous here.

And of course, doughnuts and hot cider. Come be as happy as these volunteers last year!

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Continued Drought, and some hope

The drought continues here on campus, and in the broader Champlain Valley. Our last rainfall was .4″, and after transplanting a tree afterword I saw the ground had only gotten moist about 1″ down-powder dry soil beneath.

I forget where I found them (probably Lifehacker), but some recent pictures of the US taken by the Gravity Recovery and Climate Experiment satellites show in stark maps the bubble of drought we seem to find ourselves in right now. The first map shows soil surface moisture, moisture in the first centimeter of soil. Look for the little dark red blob right on top of Middlebury. (click on maps for larger view)

soilmoisture_gra_2015257_sfsm_lrg

The next shows root zone soil moisture, the top meter (39″) of soil.

soilmoisture_gra_2015257_rtzsm_lrg

This final map shows ground water in shallow aquifers (like the well at my house!).

soilmoisture_gra_2015257_gws_lrg

I’ll include the overall map of all three maps, which give a legend to the colors. The explanation is as follows (and is quite scary!)-“The maps do not show an absolute measure of wetness, or water content. Instead they show how water content in mid-September 2015 compares to the average for the same time of year between 1948 and 2012. Dark red represents areas where dry conditions have reached levels that historically occur less than 2 percent of the time (once every 50 or more years).” Note how we are in the dark red in all three maps.
soilmoisture_gra_20150914

If you have a little bit of time, by all means read how gravity sensing satellites can figure out how much water is in the earth. In a nutshell, it’s two satellites seperated by 139 miles, and sensing how much they move towards or away from each other as they orbit minute changes in gravity from earth can be measured. The complete explaination is at http://earthobservatory.nasa.gov/Features/GRACE/ .

Hope is on the way, though. We’re looking at a pattern change, with a cold front moving into the area and drawing moisture into the region, possibly an inch of rain or more. That’s a good start. Here’s a good rundown from the Northeast River Forecast Center.

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Drought Stress

Our barely green lawns across campus belie a hard fact this summer-it’s been dry. Very, very dry.

Funny, considering how wet it was in late spring, when it was almost too wet to do anything outside. The High Plains Regional Climate Center (kick ass website for weather geeks!) maps show we have 25% of the normal precipitation in the last two months, that’s a 6″ deficit of rainfall.

60dPNormNRCC60dPDeptNRCC

A general rule of thumb I can’t find a reference for but I always tell anyone is that Vermont plants need a 1/2″ of rainfall per week for optimum growth. We’ve had only about 1″ in all of August, and only 1″ in July. Most of that falling in one day, leaving our clay soils to dry out and become nearly resistant to small rainfalls.

The early leaves you see falling are signs of that. Trees in temperature zones such as ours develop wide, spreading root systems, not going too deep in search of water or nutrients. In fact, much of our campus is on ledge, with very little topsoil available, meaning plants need to go shallow and wide to root into the ground.

(My unsubstantiated theory is that Middlebury was founded where it is because of the ledge-poor soils make poor farmland, and why waste valuable agricultural soils and farmland on something as unimportant as a college? Farmland in 1825 was precious, hard earned space, so let the geeks have the hill, we’ve got crops to harvest)

These wide spreading root systems enable fast, efficient uptake of water and nutrients in poor soils and a short growing season. In ordinary years, this is ideal, but in dry years, this strategy can be costly. As you can imagine, the shallow soils dry quickly, and the plants don’t have the deep extensive root systems to find moisture in the lower soil profiles. Trees are gamblers, and they’ve got a losing hand this year.

Older Black maple in the Library quad showing drought stess in the upper canopy.

Older Black maple in the Library quad showing drought stess in the upper canopy.

Flowers and other perennials show stress by wilting-the curling of the leaves cut down on the loss of water through the stomata (transpiration, if you want to flash back to high school biology). Trees react like that too, but also have the ability to shed leaves. We are seeing this now, and it may cause an early fall. The inner leaves on trees turn color and fall away, a survival mechanism. Inner leaves in the crown are not as efficient, they don’t photosynthesize as well, and therefore are not as “useful” to the tree as the outer, younger leaves. In desperation, the tree will shed the inefficient leaves ,brutally choosing the younger leaves to use the precious remaining water they have remaining.

Younger Red maple showing classic drought stress-note interior leaves browning with ends of branches still green

Younger Red maple showing classic drought stress-note interior leaves browning with ends of branches still green

Closeup of foliage

Closeup of foliage

We’ve had a little bit of rain this weekend, and more is coming, so luck it will come in time to prevent a wholesale dropping of leaves before your parents come up for fall family weekend. Snake Mountain above my house is starting to turn brown along the ledges, though, though, so lower expectations while you can.

Snake Mountain, early September. Note the brown stretches of foliage, probably on ledge.

Snake Mountain, early September. Note the brown stretches of foliage, probably on ledge.