Sunday, September 13, 2015

Drought and Snakeweed

Weather: Dry, with only a wetting on 9/4.

What’s blooming in the area: Hybrid tea roses, buddleia, silver lace vine, trumpet creeper, datura, morning glories, sweet pea, alfalfa, Russian sage, annual four o’clock, bouncing Bess, Sensation cosmos, African marigolds, coreopsis, zinnias.

Beyond the walls and fences: Goat’s head, bindweed, green-leaf five-eyes, yellow and white prairie evening primroses, leather leaf globe mallow, green amaranth, pigweed, native sunflower, gumweed, goldenrod, áñil del muerto, Tahoka daisy, golden hairy asters.

In my yard: Yellow potentilla, garlic chives, calamintha, lead wort plant, larkspur, winecup mallow, pink evening primrose, scarlet flax, Maximilian sunflowers, Mexican hat, black-eyed Susan, chocolate flower, blanket flower, bachelor button, Mönch aster, yellow cosmos.

Bedding plants: Sweet alyssum, snapdragon, marigold, gazania.

What’s blooming inside: Zonal geraniums.

Animal sightings: Small birds, geckos, cabbage butterflies, bumble bees, grasshoppers, ants.

Weekly update: Drought is a progressive condition, or perhaps I should say, a retrogressive one. If the intervals between dry spells aren’t long enough for vegetation to recover, each one makes conditions worse.

Say, for example, a drought kills 5% of the vegetation, and 2% recovers. When the next drought destroys another 5%, that’s 8% gone.

New Mexico had severe droughts in the 1930s and again in the 1950s. The Santa Cruz reservoir went dry in 1956. More dry years occurred in the late 1970s. It may have been wet after that, but damaged grasslands didn’t recover enough to survive the recent bad years.

My front yard was in poor condition when I came here in 1991. All the slope supported was ring muhly grass, winterfat and broom snakeweed.

When we had some dry years around 2007, the ring muhly died. Broom snakeweed colonized areas where water seeped from beds I was watering. I left the upland undisturbed, and so it remained impervious to weed seeds.

We had a very bad year in 2012, when water was severely rationed by the ditch managers. Needle grass on local grasslands suffered. Russian thistles invaded the next spring. The land to the south and west of me was devastated for the first time since I’ve been here.

Last year, the carcasses blew in the wind, and water was still rationed. However, there was just enough rain to revive the dead crowns.

Nothing much happened in my yard in 2014, but we had rain this year in late spring and mid-summer. My previously barren ground sprouted Russian thistles everywhere. They didn’t come from those carcasses, but from seed blown off the land to the south and west. It had been an aerial assault.

Elsewhere, broom snakeweed appeared everywhere in late summer on hillsides that had lost some of their cover. Some had continued to be grazed a few weeks a year by horses

but other parts haven’t been grazed in the last 20 plus years.

Some experts point to the yellow flowered shrub as an indicator of land abuse. Others note, when it’s invading it slows or prevents soil erosion. It’s part of nature’s repair kit when things go awry.

Notes: Broom snakeweed is Gutierrezia sarothrae. Russian thistles are Salsola pestifer. Ring muhly is Muhlenbegia torreyi. Winterfat is Eurotia lanata. Needle grass is Stipa comata.

Tirmenstein, D. "Gutierrezia sarothrae," 1999, in United States Forest Service, Fire Effects Information System, available on-line; summarizes research on the composite.

1. Broom snakeweed in my yard, 12 September 2015.

2. Snakeweed floret, 12 September 2015.

3. Front yard before it was destroyed by drought, 26 August 2006. The purple haze is ring muhly grass. The grass in front is black grama. Winterfat is the gray shrub in back.

4. Front yard two years later, 2 August 2008. The gray rings in front are the dead muhly. The rest is winterfat.

5. Local prairie after the drought killed the needle grass (the black clumps) and Russian thistles had invaded (the green), 24 August 2013.

6. Local prairie with the needle grass reviving, and the Russian thistle carcasses blown away, 20 March 2014.

7. My front yard this year, after those seeds from the local prairie landed, 6 September 2015. The rust is Russian thistle, the yellow is broom snakeweed, and the gray is winterfat.

8. Area hillside covered with broom snakeweed, 10 September 2015.

9. Arroyo flood plain across the road from the hill in #8, 10 September 2015.

10. Same flood plain as #9 before most recent dry years, 2 November 2011.

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