Tag Archives: trees

The Physics of Sap

by Barbara Walvoord

from Lathrop Lamp Post, March 30, 2017

A bruised branch we see in the woods these days is likely to be oozing sap.  As we drive through our countryside, smoke rising from a shack along the road tells us the inhabitants are “sugaring.” Those of us who don’t do our own “sugaring” trek to the Hadley Sugar Shack for pancakes drowned in real maple syrup.

Behind this common New England scene lie some amazing physics.  Sap flows because of carbon dioxide–yes, that gas we have too much of, causing climate change.  But inside a tree, carbon dioxide is essential. A tree has a problem–it has to get nutrients and water to its branches and roots, especially in spring when it’s trying to nourish new shoots and buds.  It can’t burn coal for electricity, as we do to move heat and water through our homes.  Instead, a tree uses the properties of carbon dioxide, and the spring changes in temperature, to push around the life-giving sap.

Sap flows through a portion of the outer tree trunk called sapwood. Sapwood consists of actively growing cells that conduct water and nutrients (sap) from the roots to the branches of the tree. During the Continue reading The Physics of Sap


Lathrop’s Christmas Trees

by Barbara Walvoord

Way back into history,  the shortest days of the year have been a time to fear cold, storm, hunger, and evil spirits. Evergreen trees symbolized the ability to survive the winter and the promise of a green earth.  People brought evergreens into their homes as protection against evil spirits.

Today, many Lathrop residents will bring cut Christmas trees into their homes, but our Lathrop land–our wider home–has thousands of evergreen trees, not just symbolizing the ability to survive the winter, but actually helping our creatures do so.

The two most common evergreen trees on Lathrop land are eastern white pine (Pinus strobus) and eastern hemlock (Tsuga canadensis). Together with our red maples and white oaks, they form a common type of New England forest that, if kept healthy, nurtures a rich diversity of wildlife.

One thing our evergreens do is provide dinner: seeds of white pine  and hemlock feed rabbits, squirrels, bears, and many birds including Continue reading Lathrop’s Christmas Trees

An Ill Wind at Lathrop

by Barbara Walvoord

(first published in the Lathrop Lamp Post, Sept. 23, 2016)

Last week, a strong wind broke a big limb from a cottonwood tree by the Bassett Brook bridge on the east campus.  Awww, what a shame.  But, as my mother used to say, “It’s an ill wind that blows nobody any good.”  Mother Nature will make a good thing from last week’s wind, no matter what happens.

The first thing that will happen is that our cottonwood tree will send up chemicals to try to deter disease organisms and wood-decaying fungi from entering the wound. Then it will try to cover the wound with a special woundwood or callus. Continue reading An Ill Wind at Lathrop

Lathrop’s Amazing Red Maples

by Barbara Walvoord

Red maples (Acer rubrum) are so common we might take them for granted.  But in fact, they are amazing, as the US Forest Service reports (http://www.na.fs.fed.us/pubs/silvics_manual/volume_2/acer/rubrum.htm):

Their range is the eastern U.S. and part of Canada, from Nova Scotia to Florida–some 1600 miles.

Red maples grow in locations from  dry ridges to swamps. “They can probably thrive on a wider range of soil types, textures, moisture, pH, and elevation than any other forest species in North America,” says the U.S. Forest Service. Red maple seedlings can develop different root systems: in wet soils, a short tap root with many lateral roots; in dry soils, a long taproot with less lateral growth.

Red maple seeds have a germination rate as high as 91%, and the seedlings are shade tolerant. Thus a maple forest has a huge reserve of small seedlings growing in the shade of the larger trees.  These seedlings will eventually die from lack of sunlight, to be replaced by other seedlings, until one of the large trees falls, so the lucky youngsters in the path of new sunlight can shoot up fast.

And get this: In southeastern Ohio, an 8-acre mature oak-hickory stand, with no red maples, was clearcut. Six years later, the same ground contained more than 900 red maple seedlings per acre. They had winged their way from the few red maples in the nearby forest.

Red maples support the larvae (caterpillars) of  285 species of butterflies and  moths–a banquet for nesting chickadees or bluebirds, which need mostly caterpillars to raise their young (http://www.bringingnaturehome.net/what-to-plant.html).

Red maples are wonderful shade trees, with beautiful spring blossoms and brilliant autumn leaves–and they grow fast. If you live in an east campus cottage, look in your mailbox soon for a chance to plant a native red maple to shade your porch or patio and reduce your summer air conditioning.

Still Green at Lathrop

by Barbara Walvoord

If you walk through our woods at either campus this time of year, you may spot mountain laurel (Kalmia latifolia), still sporting its shiny, oblong green leaves among the brown, bare branches of our oaks and maples. I took this photo on January 12, 2016, at the far west end of Mulberry Meadow, near Bassett Brook, which you can see in the background, with its border of snow.

Mountain laurel’s beautiful flowers have an unusual way of dispersing their pollen. Many other flowers lift their stamens, covered with pollen, and passively wait for an insect to crawl around Continue reading Still Green at Lathrop

Succession at Lathrop: The War of the Woods

by Barbara Walvoord

Resident Eleanor Herman took this photo on the east campus wide woods path. In a peaceful winter scene, darling little baby pine trees cluster around the skirts of their mother trees, and the in-woods meadow glistens with mist in the background behind the trees.

But this is actually a scene of movement and change–a scene of forest succession, which is taking place in all our woods on both campuses. The white pine seedlings in Eleanor’s photo are part of Continue reading Succession at Lathrop: The War of the Woods

Lathrop’s Tough “Old Hickories”

by Barbara Walvoord

Here’s a trivia quiz: Which U.S. President was called “Old Hickory” and why?

We have some shagbark hickories on our land right now (Carya ovata). And yes, like Andrew Jackson, who survived brutal battles in the war of 1812 to become our seventh president, these trees are very tough, and they’ve escaped many potential dangers.

There is a line of shagbark hickories on the east campus Mulberry Meadow. Walk behind the Mulberry Lane homes and take the mowed grassy path across to the far side of the meadow, and then west along the row of trees that separates our property from the property next door. In that row, look for the trees with the very shaggy bark.

These hickory trees are survivors. They escaped being cleared to make room for crops, either on our side or on the neighboring field. They escaped being cut down for their hard, shock-resistant wood Continue reading Lathrop’s Tough “Old Hickories”