Norway Maple

I’ve been thinking a lot lately about one of the more contentious trees in our urban forest, the Norway maple. Late this fall, while the leaves were still turning, I recently closely inspected over ⅔ of our campus trees, looking for problems, and Norway Maple kept appearing in the problem lists, with similar patterns of failure.

Norway Maple-healthy young tree

Some would say this is to be expected. Norway maple has been an extremely overused plant in the North American landscape, a victim of its own success. 100’s of cultivars have appeared over the years, including one of the most popular shade trees, Crimson King Maple-what most former customers of mine would simply call “Red Maple”, for its dark red leaves all summer long.
John Bartram, one of the fathers of early American botany, introduced the Norway maple in 1756, after receiving seedlings from Philip Miller in England, and started selling them in 1762. The trees remarkable adaptability to varying site conditions, including a broad tolerance of soil texture and pH, made it a popular tree among early arborists and gardeners. And a knack for sending out sports made it one of the first trees to get cultivars selected from it.

Norway Maple,  Acer platinoides,  flowers attractively in the early spring, late April here, with clusters of yellowish green flowers appearing before the leaves, each flower about ⅓” in size, but held in large clusters called corymbs, completely covering the tree. Norways are actually one of the most attractive early flowering trees. Bright yellow fall color can frequently be seen, in years when Tar spot doesn’t decimate the crown foliage.

The flowers turn into large seed pods called samaras, with a pair of seeds held in the center, and large flat wings spreading to each side. Split in half, and each side will helicopter towards the ground slowly, or alight in a breeze and fly for some distance. The wings of the helicopter extend around the seed, and can be opened like a book, where the milky white sap inside can act like a glue, allowing the samara to be attached to one’s nose, where it can stay stuck until nap time.

This milky white sap is a great way for the confused to identify Norway maples, as the similar sized Sugar and Red (Swamp) maples have a clear sap when broken. Spend some time with them, though, and identification becomes easier. The bark is a dark gray, and is ridged and furrowed, unlike any native maple. The leaves are large and dark green, larger than any other maple around, and while similar to Sugar maple, are flatter at the base.

It’s the leaves that cause many of the problems of the species, a victim of their own success. The size of the leaves create a super dense shade, making growth for grass underneath nearly impossible, but also for any interior growth on the tree itself. All the leaves on a Norway maple, and therefore all the growth, is on the outside of the tree. This is a red flag in the tree structure world, where all the end weight of the tree, and all of the wind load, is not shared throughout the tree, but, being held at the ends of the branches, and can be prone to breakage. Fortunately, the wood is fairly strong, and failure is more often seen in bad branch angles. The bare interior of a Norway, though, to me, is as distinctive an identifying characteristic as anything else.

Trunk Failure from Bad Branch Attachments

The dark dense canopy from the leaves also aid in the invasiveness of the species. Norway maple has been outlawed for sale in southern New England, and will become so in Vermont in a couple of years. The shade tolerance, in addition to its own dense shade, and its shallow root system makes the tree a fierce invader in the forest ecosystem, out-competing native maples in the understory, and inhibiting native seedlings (Galbraith-Kent, S. L. and Handel, S. N. (2008), Invasive Acer platanoides inhibits native sapling growth in forest understorey communities. Journal of Ecology, 96: 293–302. doi: 10.1111/j.1365-2745.2007.01337.x) . The shallow roots also hinder the growth and development of native forest flower species.The tree itself hosts less native caterpillars than other native maples, and North American mammals don’t recognize the seeds as a food source.

Norway maple gets its name from the northern end of its native range, and the population extends through the Caucasus and Turkey. There, the tree flowers 3-4 weeks earlier than the similar Sycamore maple, and is thereby kept in check, as both trees are insect pollinated, but the earlier flowering means only 5-15% of the seedling forest population seems to be Norways. Normal longevity for the species only seems to be 100-150  years, although trees in it’s preferred habitat, the Balkan peninsula, lives to about 200.

Our campus trees seem to be failing all at about 100 years as well, for a variety of causes. As mentioned above, Norways seem to be prone to bad branch angles, where cavities form and cause holes in the branches and trunk. Another problem with the tree seems to be a propensity towards girdling roots-roots that circle around the trunk underneath the ground, choking itself off. Norways make up about 10% of our tree population, but account for more than that in shade canopy, so, while they are invasive, we clearly can’t actively remove them. Some younger trees are in front of Forest Hall along Route 125, as well as in front of Emma Willard. The largest specimen is on the north side of the Axinn Center, a tree held together by a jungle of cables up in the crown.

Over-Mature Norway Maple at Axinn

Why?

7-18-6.

Not a fertilizer label, but an accounting of the fall semester at Middlebury. Seven-the  number of weekends in a row we’ve seen vandalism against trees. 18-the total number of trees affected. And 6-trees killed outright.

We come into work Monday morning, and, in addition to picking up the inevitable and ubiquitous litter and detritus from the weekend, now survey the damage as well. I was not writing of it, hoping to sweep our problem under the rug, hoping that these acts were random, solitary, maybe just an aberrant mutation on an otherwise pristine campus, a passing social deviation that would go away on its own.

And I’m preaching to the choir, here, after all. I’ve discussed vandalism in the past on Middland, and am quite frankly a little sick of telling the tale. I’ve reported this problem to my superiors, and they’ve approached community council. And I was going to get on with life, and write posts on annuals, the Sustainable Sites Initiative, and put some more work into Turf Battle.

Last night, Dean Shirley Collado wrote a piece on One Dean’s View called Plates and Privilege. We’ve all heard about the missing plate problem, thanks to Aunt Des and the great communications department. But Shirley’s take is different, and had me thinking all night (well, until 9:30 or so, I can’t seem to stay up like I used to) about privilege. Let’s let her say it best:

I would like to call students to action to think more critically about the human face behind the dish problem. Think about what it says about us as a community when these small acts of thoughtlessness create a collective problem that impacts all of us in a negative way. This thoughtlessness speaks volumes about what kind of people our students are going to be when they leave this institution.

So, I thought, our tree vandalism is a problem of privilege, like the many beer cans scattered around on a Monday. It’s easy to take trees for granted, and yes, sometimes they do get in the way (I’ve wondered on one or two broken branches if the offender was tall-sick of running into the same branch every day).  But then I cleaned up some of the damage today, and came to a different conclusion.

We have a problem of violence.

Pictures won’t even do it justice, and even my words won’t. In the service building? Come by my office, I’ve saved a couple pieces of broken limbs. But let me try to explain what’s going on here.

The offender (I hesitate to use the word ‘student’, as surely this individual isn’t really learning anything here) is breaking limbs off of trees. Serious limbs. I climb trees, and, while I still resemble the pasty geek I was in high school, I’ve jumped a couple of weight classes. Limbs broken would hold me and my chainsaw with room to spare. Limbs that are not just snapping off, but need to be bent, wrenched, moved back and forth hoping to break 3” of bark and wood to separate it from the tree. Entire small trunks of immature trees not only bent to the ground, but shaken, trampled, twisted and torn, sometimes breaking completely, sometimes left hanging , or lying in ground, waiting for a chalk outline to surround it. This is an act of rage, of violence, well beyond wanton destruction of property, senseless passing violence against an animate object incapable of screaming or defending itself.

A 3” limb, counting rings, is probably very well older than the person breaking it off.

Monday will come again, and again we’ll go out, willingly pick up the remnants of a privileged life, but hope and pray that no more violence has befallen our silent friends.

Turf Battle-the Redesign of Atwater

As you may have read in the email from Tim Spears, the Master Plan Implementation Committee is sponsoring a contest to redesign the Atwater Commons area of campus. You can read all about it on the blog dedicated to the project at http://sites.middlebury.edu/turfbattle/, where myself and several others will be writing.

I’ll be blogging here about the contest as well. Posts on the contest site will be specific to the contest, so all you wonderful readers  here will probably not find it all that exciting. On Middland, though, I’ll be blogging more general topics, hopefully some of interest. Topics like Sustainable Landscaping, some design theory, rain gardens, maybe even down to lists of favorite plants.

Why have students design a significant portion of the landscape here? I will admit to having moments of control issues, so the intitial reaction of a student design might be one of dismay. Lately, though, I find myself walking on campus at nights, or on the weekends, and I’m amazed by how different the campus is. It’s not just seeing things at a new time of day, it’s more than that. Without the faculty, staff, cars, gators, lawn mowers, pick up trucks, all that, the campus seems more homey. The sidewalks seem busier, and there seems to be a buzz, a background hum of activity that makes Middlebury seem exciting, a fun place to live.

So I’ve realized, well, I don’t live here. It’s not my school. (Maybe I’ll claim ownership of a couple of trees, but, spend some time climbing them for work and it’s nice to be on a first name basis.) Who better to plan a major outdoor living area on campus than its residents? While I think that everybody that lives and works here should have a say in the landscape, I’m excited to see just what the students want to do with their campus. I invite you to join the discussion, either here or on the Atwater contest blog, and let your voice be heard as well.