Sunday, November 18, 2007

Sugar maples

Sad to say, they're in decline. Everyone's favorite tree at this season, sugar maples are declining where we most would like them to be at their best: lining suburban streets. The trees seem most suited to a rural environment. The stresses of suburban living get them down.

What's the problem? Sugar maples are happiest in loose, moist soil. The dry, compacted soils of curbside planting strips disagree with them. More serious problems for sugar maples are urban pollution, road salt, and acid rain. The bottom line: their numbers are falling in this area.

Many writers have commented on the decline of the sugar maple in the suburban northeast. The most poignant account I have seen is in Brian Donahue's book, Reclaiming the Commons. It is Mr. Donahue's peculiar utopian goal that every town should have a community farm. In his book he recounts his experience establishing and running such a farm in a bedroom suburb of Boston. Part of his crop was maple syrup harvested from trees on the suburban streets. As years went by, his maple syrup production dried up because the community's trees were dying off, killed by road salts and automotive pollution:

"During the 1980s sugar maples all over town began disappearing, like the elms half a century before them. By the end of the decade it was as if the maples had never existed --- only a handful remained.... The maples were a casualty of the automotive suburb, and their passing the quest to commute from urban blight to rural sanctuary is self-defeating.... To believe that we can routinely drive great distances to reach an unspoiled landscape full of natural amenities at the end of our journey is a fatal delusion. If we want to live in towns with healthy sugar maples, we simply have to live in them more and drive in and out of them less. We cannot out-commute suburban sprawl."(1)

More problems for sugar maples in our area? Climate change: sugar maples like it cold. The species is often used as the poster-child example of plants that are migrating northward with global warming, as it was in AOL's November 17 report on the latest warming forecast of the Intergovernmental Panel on Climate Change.(2)

How about some good news? Plainfield still has some very fine sugar maples. A particularly nice one is at the Van Wyck Brooks house at 563 West 8th Street.

Other good examples are on Watchung Avenue near Colonial Circle, pictured at the top of the page. Sugar maples near 1326 Prospect Avenue, photographed this afternoon, were still making a very attractive display.

A younger tree, photographed three weeks ago, illustrates the fiery brilliance of sugar maple foliage in bright sun.

Maple syrup anyone? European settlers learned about it from Native Americans, for whom it was the primary sweetener. They concentrated sugar maple sap by freezing it and removing the ice or by placing heated stones in it to cause evaporation of water.(3) It takes about 40 gallons of sap to produce one gallon of maple syrup.

The quintessential maple leaf is the sugar maple leaf. It is the leaf represented on the Canadian flag. It closely resembles the leaf of Norway maple. The two species can be distinguished at a glance by their bark. Sugar maple bark forms shaggy, platelike scales. Norway maple bark is shallowly furrowed.

This year's sugar maple foliage season is near its end on Plainfield's streets. Have a look if you haven't already and enjoy the show.

(1) Reclaiming the Commons, Community Farms and Forests in a New England Town, Brian Donahue, Yale University Press 1999, pp. 166-171.

(3) A Natural History of North American Trees, Donald Culross Peattie, Houghton Mifflin 2007, p. 356.
Copyright Gregory Palermo

Sunday, November 4, 2007

Red: the color of health. Sourwoods, dogwoods, and sweetgums.

Inspired by the "French paradox" of long lifespans in a population with a high-fat diet, some of us hope to stay healthy by drinking plenty of red wine. Many plants adopt a similar strategy by producing red leaf pigments in the fall. The spectacular reds and maroons that light up the autumn landscape are the colors of anthocyanins, a family of antioxidant compounds. These antioxidants protect plants (and us) against chemical injury caused by oxygen, a highly reactive and dangerous molecule.(1)

Some of the best red foliage is visible in Plainfield now. Red maples, sugar maples, and Japanese maples are famous for their red foliage. One of my favorite small trees is sourwood, Oxydendrum arboreum, a native of the southeastern United States that is scattered around Plainfield in small numbers. A fine example is at Watchung Avenue near the corner of Kensington.

The tree highlights its maroon leaves with cream-colored seeds.

One of the many charms of our native dogwood is its beautiful maroon fall foliage.

Sweetgums, maligned for their production of difficult-to-rake gumballs, more than make up for whatever maintenance problems they cause with a panoply of red fall colors.

Some sweetgums have autumn foliage in yellow tones.

Deciduous plants don't just passively lose their leaves in the fall. They make elaborate preparations for winter. Red antioxidant coloration is part of that preparation. Green leaves are colored by chlorophyll, the molecule that allows plants to capture the energy of sunlight. When the leaves are shed, plants don't allow the chlorophyll to go to waste. They break it down and move the breakdown products to the roots, where they are stored over the winter. With their energy-generating machinery moving into storage, plants are in a vulnerable state. As they lose their chlorophyll, the leaves of some plants gain protective anthocyanins and reddish colors. The latest scientific thinking about why the leaves of those plants turn red in the fall is that additional antioxidative protection in dying leaves permits orderly breakdown and withdrawal of the chlorophyll before the leaves fall. This subject is nicely summarized by Colin Tudge in his recent book, The Tree.(2)

Some autumn leaves develop yellowish tints. Where do those colors come from? Yellow autumn leaf pigments are generally chemicals that have been present all during the growing season and that are unmasked by the absence of chlorophyll. Yellow and orange carotenoids play a role in photosynthesis. They are also antioxidants.(3)

(1) Blueberries are touted as good sources of anthocyanins. A widely cited study found that elderly rats had an improved sense of balance after being fed large quantities of blueberries for weeks.

(2) Colin Tudge, The Tree, A Natural History of What Trees Are, How They Live, and Why They Matter, Crown Publishers, 2006, pp. 357-359. The author points out that new spring leaves and shoots, also particularly vulnerable to injury, have a red tinge in many plants.

(3) Beta-carotene has been a widely used dietary supplement. I suspect that its popularity fell off after scientific studies seemed to indicate that taking it did not offer the hoped-for cardiovascular benefits. Better, it seems, to get your antioxidants by eating plants, not pills.

Copyright Gregory Palermo