Trees

What’s still green: Arborvitae, juniper and other evergreens, roses, cholla, prickly pear, yuccas, red hot poker, grape hyacinth, west-facing iris, hollyhock, winecup, oriental poppy, St. John’s wort, vinca, baptista, white sweet clover, catmint, beardtongue, snapdragon, Jupiter’s beard, coral bells, rock rose, sea pink, columbine, yellow evening primrose, perky Sue, Shasta daisy, tansy, coreopsis, Mexican hat, cheat grass, bases of needle and June grasses; number of large trees still have canopies of dead leaves.

What’s red or turning red: Young apricot stem, raspberry, pink evening primrose.

What’s grey, blue-grey or grey-green: Piñon, pinks, snow-in-summer, yellow alyssum, winterfat, Silver King artemisia.

What’s yellow or turning yellow: Globe willows, apples, bouncing Bess, flax, purple ice plant.

What’s blooming inside: Aptenia and asparagus fern blooming; rochea and Christmas cactus leaves tinged with red.

Animal sightings: Rabbit hiding under car Wednesday morning; thin gray-green birds on utility line.

Weather: Cold mornings, clear starry nights, reddish new moon Thursday; last rain/attempted snow 11/15/2009; 9:05 hours of daylight today.

Weekly update: Nature never reaches an equilibrium. Something is always disrupting the balance with its demands.

Tree roots grow beyond the ability of leaves to feed them, and send messages up for more leaves. Leaves multiply beyond the ability of roots to supply them, and send help messages down. Someone cuts off parts of a tree, and new suckers emerge from hidden buds in the bark to sustain the roots.

In more temperate climates, topped trees survive on carbohydrates stored in their roots, which allow them to send out emergency branches within four to six weeks. The finer roots are sacrificed, but once some leaves are recreated, the roots return to accumulating starch in about twelve weeks. Depending on its original size, a tree can regain its original mass within a few years, although the new growth may be less securely attached to the trunk and more prone to storm damage.

Here, where dry air sucks water from the soil, trees reverse the normal process: fewer leaves mean roots’ reserves can’t be replenished. When the number of roots decreases, the branches disappear until the tree itself becomes a shadow of itself, a barely functioning trunk.

This year’s unexpected early summer rains disrupted the stasis of topped trees: roots could expand, and suddenly seemingly dead trees shot out new growth.

Down the road, someone lived under the threat of two dying cottonwoods, one directly under a utility line, one a few feet away. At some time, the tops had been removed, and the trunks had shed their bark. If there were any leaves, I never saw them from my car window.

This June they cut them to the ground, and converted the nearby garage into living space. Before they could fill the yard with a heap of foot-long slices from the trunks, new growth sprouted. By fall, the two trunks looked like shrubs.

In the village, a trailer sits behind a row of cottonwoods. Sometime in the past, one of the trees apparently died and was cut to the ground. It had sent up a new trunk that was twisted, with suckers coming from the joints in gnarled boles. When the leaves started dropping this fall, it became obvious new branches had grown from the stump this summer.

Such new growth is common for many trees, but mature cottonwoods are not known for suckering. Fires and grazing buffalo controlled their population on the prairies, and in many areas they only increased after the herds were gone.

In New Mexico, Rio Grande cottonwoods have been disappearing with artificial changes in the rivers that have reduced the amount of available water. Sprouts only survive in places where the water table is high. This summer’s rain probably made no permanent changes to the below ground water levels, but they did leave enough near-surface water to stimulate the cottonwoods to return to more active lives.

Kim Coder says, with trees, there’s "no true balance except at death’s door." This summer’s early rains were a reprieve that took the form of a great disruption of normal patterns of nature that upended expectations by homeowners who thought it finally was safe to build near the dying cottonwoods.

Notes:
Chesney Patrick and Nelly Vasquez. "Dynamics of Non-structural Carbohydrate Reserves in Pruned Erythrina poeppigiana and Gliricidia sepium Trees," Agroforestry Systems 69:89-105:2007.

Coder, Kim D. "Crown Pruning Effects on Roots," European Congress of Arboriculture, 1997.

Taylor, Jennifer L. "Populus deltoides," 2001, in United States Forest Service, Fire Effects Information System, available on-line.

Wier, Stuart K. "The Plains Cottonwood of the Southern Rocky Mountains," 1998, available on-line.

Photograph: Cottonwood stump in th village, with regrown trunk in back and new growth waving in the wind at right, 15 November 2009.