Dead Evergreens

Weather: We had rain last Sunday, and by Tuesday the humidity level was back down to 5%. I decided that number didn’t mean much, because it didn’t indicate the source for the water in the atmosphere. In much of the country, 90% of the moisture comes from oceans, lakes, and rivers, and the rest from plants. [1]

That number is deceptive because it includes the moisture from the Pacific Ocean and Gulf of Mexico. Ronald Hanson separated near and far bodies to water to suggest almost all the precipitation in the southwest came from plants, rivers, reservoirs, and the soil. [2]

During the summer monsoons we might get some moisture churned by a hurricane if it survives its transport across the intervening deserts. This past week, Aletta emerged off the coast of México and one could see its tail of water vapor reaching the Río Grande valley on Satellite images, but nothing showed on the radar scans taken closer to the surface.

Aletta’s water served a different purpose. It diffused some of the solar radiation, even though afternoon temperatures were still in the low 90s. The sun’s heat, and implicitly the journey to and from the solstice, remain what drives our weather.

Transpiration, or the release of water by plants, is a function of photosynthesis. When temperatures rise, plants open their pores and release water. [3] The moisture then creates a cooler zone around the plant. The wind moves that cooled air away, forcing the plant to emit more water to protect itself. Thus, the winds and high temperatures caused by a lack of cloud cover reinforce each other in producing drought conditions. [4]


Different categories of plants handle extreme heat differently: some like grasses have changed their metabolic cycles to operate at night, and others like cacti slow themselves. Seeds that have sprouted wilt by noon and stop growing, peony buds die unopened, and daylily, hosta, and morning glory seedling leaves lose color in the sun. Evergreens reflect less light than desert sands, and so retain their heat and suffer more. [5]

Last rain: 6/3. Week’s low: 43 degrees F. Week’s high: 93 degrees F

What’s blooming in the area: Dr. Huey and hybrid roses, yellow potentilla, silver lace vine, honeysuckle, daylilies, lilies, red hot poker, red-tipped and weeping yuccas, Spanish broom, Russian sage, purple salvia, hollyhocks, Jupiter’s beard, snow-in-summer, datura, sweet pea, hollyhocks, dark purple larkspur, yellow yarrow

We had the apricot and cherry frosts this year, but were spared the catalpa one in late spring that destroys emerging leaves. As a result, the tall, white-flowered trees were in full bloom everywhere this week. The one in my yard was fragrant and had more internal leaves than it had last year.

What’s blooming in my yard: Rugosa and miniature roses, desert willow, cultivated tamarix, Maltese cross, golden spur columbine; foxglove, smooth, purple, and coral beards tongues; Johnson Blue geranium, catmints, Romanian sage, winecup mallow, blue flax, tomatillo, pink evening primroses, Shasta daisy, Ozark coneflower, white yarrow, chocolate flowers, coreopsis, blanket flower

What’s blooming outside the walls and fences: Cholla cactus, alfilerillo, purple mat flower, white tufted evening primroses, scarlet bee blossom, velvetweed, bindweed, silver leaf nightshade, greenleaf five eyes, leather leaf globemallow, showy milkweed, buffalo gourd, scurf pea, alfalfa, white sweet clover, tumble mustard, Queen Anne’s lace, Hopi tea, fleabane, common and native dandelions, goat’s beard, plain’s paper flower, golden hairy asters, Tahoka daisy; brome, cheat, purple three-awn, and rice grasses.

Three awn and dead western stickseed were releasing their seeds.

What’s coming up: Zinnias and African marigolds were putting out their second leaves; the other seedlings were in remission.

Bedding plants: Sweet alyssum, pansies, violas. At least two people had put petunias in containers.

Tasks: Now that I finished clearing the garlic chives from the pinks and snow-in-summer bed, I started salvage operations in the main garden. I began by cutting down the white sweet clover that had reached three feet in height. Heavy blades like loppers and pruners don’t cut green stems, and the smaller nippers can’t handle the thickness of the stems. I did managed to get the much abused, dull loppers to do it anyway, because I didn’t care how much they tore the stems.

When I cut down the unwanted sprouts that had come up far from the parent black locust, I discovered the elms they were hiding. Neither can be controlled by simply chopping them down, and both come up in the middle of other plants where they can’t be poisoned.

Animal sightings: Small brown birds, geckos, sidewalk ants, cabbage butterfly in alfalfa, bumble bees on sweet peas, small bees, hornets, other small flying insects, grasshoppers eating flowers of Shasta daisies; heard crickets

Someone imported a herd of goats to mow down its grass; it was gone an hour after I first saw them.

Thursday morning I discovered a small trench where I had planted melon seeds on Tuesday. It wasn’t there when I watered the area Wednesday noon.

Strong, twisting winds around 8 pm Wednesday brought down more dead wood in the black locust. This particular limb had been there several years, and was taller than the newer growth. The birds used it, rather than the utility line above, as their sentry point.

Weekly update: Drought is insidious. One can see the damage on the surface, and one hears about changes in the levels of the water table. What one doesn’t observe what happens between those two levels until the tall evergreens start turning brown. Then, it’s too late to do much.

I first noticed the problem with deep water levels in 2011 when the leaves on my catalpa turned white. As I wrote on 21 August, the immediate cause was a lack of iron. I reasoned that sufficient iron was in the soil, else the tree wouldn’t have grown. However, iron was water soluble, and I thought it possible enough water had been pulled from the level of the tree’s roots so the iron no longer was dissolving at the same rate. I started giving the tree more water, hoping some would seep down to the lower roots.

Most do nothing because the trees don’t die, and appear normal the following spring after the winter has replenished the soil. The etiolation doesn’t begin until mid-summer. The week of rain last October may have done as much for this year’s catalpa florescence as the spring frost cycle.

Many of the tall evergreens that died were near houses that were vacant, had changed hands, or become rentals after the original owners died or moved because they were too sick to remain in their homes. The new people may not have cared, or assumed that trees simply existed without care. They usually were quick enough to call someone to cut down the carcasses.

Some, especially piñons may have been killed by bark beetles. However, my understanding is they attacked plants that already were having problems.

The first to die were what I thought were Douglass spruces. I was never sure because the range of Pseudotsuga menziesii menziesii is 7500', and this is much lower. [6] That alone would explain why it was the first tree I saw die in 2013. Another went in 2015.

Those trees were all close to the river, maybe 1000' to 1500' away. Two years ago three tall evergreens died on a property along a road that was twice as far from the Río Grande. It had been vacant for a year, and while I never saw anyone irrigating, someone must have been running a ditch somewhere in the vicinity.

Last year tall trees died in three more places.

Notes on photographs:
1. Remains of what had been a row of five tall evergreens after the house was vacant, 23 May 2018.  You can see the roof of the one-story house at the bottom left.

2. Dead evergreen in area where other trees are doing OK at house with a neglected yard, 23 May 2018.

3. Dead evergreen towering above a one story house, 23 May 2018.

4. Dead evergreens fifty feet from an arroyo that no longer runs freely, 23 May 2018. They all are above the roof of the one story house in the foreground.

End notes:
1. "Evapotranspiration - The Water Cycle" on the U. S. Geological Survey website.

2. Ronald L. Hanson. "Evapotranspiration and Droughts." 99-104 in National Water Summary 1988-89--Hydrologic Events and Floods and Droughts. Edited by R. W. Paulson, E. B. Chase, R. S. Roberts, and D. W. Moody. U. S. Geological Survey, 1991. Abbreviated version on U. S. Geological Survey website.

3. Evapotranspiration.
4. Hanson.
5. Hanson.

6. E. O. Wooten and Paul C. Standley. Flora of New Mexico. Washington: National Museum, 1915. 25. They identified the species as Pseudotsuga mucronata.