Sunday, October 12, 2014

Tree Rings

Weather: The remnants of hurricane Simon hobbled across the skies, trapping smoke from a controlled burn on Wednesday, before leaving some water Thursday and Friday. The smoke, which drifted south from 3,700 burning acres between Vallecitos and El Rito, enveloped the area in a white bubble that reached the ground by mid-morning.

What’s blooming in the area: Silver lace vine, datura, morning glories, sweet pea, Russian sage, red amaranth, zinnias from new seeds and reseeds, African marigolds from seed, Maximilian sunflowers, pampas grass.

Morning temperatures fell into the high 30s early in the week. Trees have responded by draining their chlorophyll. Cottonwoods are looking chartreuse, the big weeping willow shows some yellow, the exotic trees with fine leaves are yellower still. My apricot is beginning to reveal its orange.

Beyond the walls and fences: Pink and white bindweed, goat’s head, stickleaf, Queen Anne’s lace, chamisa, snakeweed broom, broom senecio, áñil del muerto, golden hairy and purple asters.

In my yard: Large-flowered soapwort, hollyhocks, winecup mallow, catmint, calamintha, David phlox, Mexican hat, black-eyed Susan, chocolate flower, blanket flower, anthemis, coreopsis, chrysanthemum, white yarrow.

Bedding plants: Blue salvia, French marigold.

Seeds: Reseeded Sensation cosmos from last year’s plants, yellow cosmos.

Animal sightings: Geckos, small birds, grasshoppers, large and small black ants.

Weekly update: Hopi history is retold as a series of migrations. People look out over local ruins and say, once a clan lived there, now they live here. Once we lived below, and now we are here. Once the kachinas lived with us, now they are below.

It is not the progressive history of Anglos. There is no once I was poor, now I am rich, no once I was damned, now I am saved. There’s no odor of feudalism binding individuals to specific places.

Elsie Clews Parsons said the Hopi narrative was, simply, a record that extended to plants, animals, even specific Kachinas. They’re all something encountered on a journey. If there’s a moral, it’s an inbred willingness to try new things, to experiment.

In the 1920s, Andrew Ellicott Douglass looked at tree rings in the beams of ruins to determine habitation dates for Mesa Verde, Canyon de Chelly and Pueblo Bonito. By chance, he discovered a period of drought between 1276 and 1299. He believed that dry period explained why people had abandoned the upper San Juan where the modern states of Arizona, New Mexico, Colorado and Utah abut.

Historians place the drought in the Little Ice Age that began in Europe in 1258. The year of famine followed massive crop failures. Thousands died in London.

Recently, scientists have suggested the event that triggered the climatic change was the eruption of Mount Rinjani on the island of Lombok in Indonesia in 1257. They had learned the destructive possibilities of volcanic ash from Krakatoa. When it flared in Indonesia in 1883, cattle died on the open range in a winter so severe, the cattle industry in this country had to be reorganized.

A team at the National Center for Atmospheric Research had already established that ice cores from Iceland showed the types of changes between 1275 and 1300 that would have been produced by such volcanic activity. Franck Lavigne’s group was looking for the event predicted by Gifford Miller’s team.

When the climate changed in the late 1200s, people either adapted like the Inuit and Eskimos, migrated like the Navajo, or died out like the Norse in Greenland. Groups fled the Anasazi villages. Some moved east to the Río Grande, others went south.

Anthropologists aren’t so sure drought was the reason people left. Some argue depredations by the aggressive Navajo, Apache and Ute were the cause. They note the Hopi originally lived in small, isolated settlements along the base of Black Mesa. Its dense sandstone trapped water from the Upper Cretaceous that seeps in permanent springs.

In the early 1300s, the original settlers, who still had water, joined the refuges on defendable mesas where they crowded into large communities in buildings of several stories. The material responses to crisis are seen as more telling than theoretical causes.

Historians had the same reaction when confronted with climate data from Europe. They are more inclined to see human actions resulting from the actions of other humans than from some natural force.

In 2011, a team at the Swiss Federal Institute for Forest, Snow and Landscape Research published the results of its study of 9,000 tree rings for 2,500 years in central Europe. They showed the Roman Empire thrived during a period of climatic stability, but that years of instability between 250 and 600 coincided with the Empire’s collapse.

Even a sudden, permanent change would have been easier to accept than the conditions suggested by Ulf Büntgen’s colleagues. Barbarians at the gates or Christians within are easier to understand than a climate that changed every few years so farmers could never adapt. When seeds that worked one summer failed the next, it was difficult to ship agricultural surpluses to Rome.

Our view of current events and history as the actions of individuals, often violent deeds by abnormal humans in failed or rogue states, makes it hard to accept some external factor like rain could be more important. Commentators attribute Sudan’s civil war to lust for oil. They describe John Garang de Mabior as a leader who recognized the dangers of Islam. Spreading Saharan drought is dismissed as propaganda from scientists bent on turning any current event into support for their dubious agenda.

We believe our advances in technology have insulated us from climate. If crops fail in Ukraine, wheat is exported from Kansas. If fish stocks are depleted on the Grand Banks, cattle ranches are developed on the borders of the Amazon.

Travelers were more than irate in 2010 when a relatively small volcanic eruption in Iceland closed airports in 20 European countries. Businessmen couldn’t understand why ash was worse than snow that was cleared with deicers. They kept thinking there was some mid-level bureaucrat who should be fired for negligence.

Our belief in human’s ability to see, record and analyze makes dairies and autobiographies more comfortable sources for historians than passive records of trees.

Büntgen, Ulf, et alia. "2500 Years of European Climate Variability and Human Susceptibility," Science 331:578-582:2011.

Douglass, A. E. "Dating Our Prehistoric Ruins: How Growth Rings in Timbers Aid in Establishing the Relative Ages in Ruined Pueblos of the Southwest," Natural History, 1921.

_____. "The secret of the Southwest Solved by Talkative Tree Rings," National Geographic Magazine 56: 736-770:1929.

Lavigne, Franck, et alia. "Source of the Great a.d. 1257 Mystery Eruption Unveiled, Samalas Volcano, Rinjani Volcanic Complex, Indonesia," National Academy of Science Proceedings, 2013.

Miller, Gifford H., et alia. "Abrupt Onset of the Little Ice Age Triggered by Volcanism and Sustained by Sea-Ice/Ocean Feedbacks," Geophysical Research Letters, 2012.

Parsons, Elise Clews. Pueblo Indian Religion, vol 1,1939.

Photographs: Tree rings are consistent within species. Büntgen’s team used oak from lowland parts of France and Germany to reconstruct spring rains. It used stone pine and larch from the Austrian Alps for summer temperatures.

1. Peach tree where limb was cut in 2013.

2. Russian olive cut down in 2013.

3. Remains of porch rafter, installed in 1994. Wood purchased from Conley Sawmill in Arroyo Seco, wood not identified on receipt, but assumed to be local.

4. When a tree is felled, the cut is horizontal across the girth; the rings are circular. Mazzard cherry cut down in 2013.

5. When a felled tree is turned into lumber, the trunk is sliced vertically; the rings become the long lines of the grain. Cherry wood in table, probably late 1800s; varnish over stain.

6. Soft pine floor in house probably built during World War I. When the wood dries, the rings separate and splinter off. Varnish over cherry stain with wood filler.

7. Red oak floor installed in 1994. The hardwood does not splinter or easily gouge; varnish only.

8. Cedar paneling purchased in 1994. The wood is not coated when fumes from the drying oils are desired to keep away insects.

9. Southern yellow pine post purchased in 2012. Yellow pine may be one of four species. Most often it is loblolly pine grown in plantations on the Atlantic coastal plain from Maryland to Texas. Rainfall encourages fast growth so the rings are much wider than those in #3. Pressure treated with copper azole to slow aging and deter insects.

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