Wednesday, June 2, 2010

Brown Snow

Susan J. Tweit described drifts of brown snow in South Park, Colorado earlier this spring. An April dust storm had carried soil from dry lowlands to the Rocky Mountains. Susan described how the dusting of soil increases the heat absorbed by the snow, melting it faster and hastening high spring river flows. This shortens the irrigation season from western rivers and reduces the water available for other uses later in the summer.

As a lowlander, I have seen where the mountain dusting of soil starts its journey.

In 2005 it seemed that the Clover fire had it in for me. After starting as a lightning strike southeast of Bruneau, Idaho on July 15 the fire, fueled by grass and sagebrush, widened as it moved north. After a half mile it found one of my research sites.

Before the fire the site had been covered with Sandberg bluegrass that brushed my knees and a sprinkling of pink and white phlox. Scattered "old growth" sagebrush with orange lichen festooning the stems were surrounded by duvets of sensuous moss.




The Clover Fire continued north for several more hours then reversed direction and burned south, swung due east for a bit, then meandered southeast for several more days, forming a lumpy burn scar visible from the air when you fly into Boise from the east. Six days after burning across the Sandburg bluegrass site the fire burned a research site where elegant Thurber needlegrass had flourished after an earlier small fire.


After burning 192,000 acres in six days the Clover Fire sputtered and died in the irrigated field just over the fence from the Thurber needlegrass ashes.

I visited the Clover Fire four months later, during clear golden fall days with nights chilly enough to send me to a motel in the nearby town of Bliss. The swells of the Sagebrush Sea had been replaced by bare soil broken by twisted sagebrush skeletons reaching skyward where the fire had cooled enough to spare them. Where the fire crossed roads it had eased enough to leave dried wisps of the previous spring's cheatgrass plants. Rare unburned islands, where the fire had been deflected around an area by rock or bare soil, contrasted with the emptiness.

Without its protective covering of Sandburg bluegrass, Thurber needlegrass, phlox, sagebrush, and moss, the soil had become restless. Roads had become rivers of fine soil dropped when the wind slowed in the lee of the berm the road grader left behind.


The soil in the roads had been scoured from other areas. In some places the roots of perennial grasses had been undermined, their leaves long ago sandblasted away by blowing soil. In other areas only spider webs of fine roots remained, incapable of catching even soil.




Although fire and soil erosion are natural processes, many areas of the West are experiencing more and larger fires. These are often followed by alarming rates of soil loss. We have changed the West.

There are more of us, driving more cars that catch fire along interstates, tossing more cigarettes mindlessly from car windows, and riding more ATVs. Earlier residents of the West brought exotic cheatgrass, which now blankets large areas with fine fuels that allow fire to spread more easily than do our larger and more widely spaced native perennial grasses.

Our recent warmer summers, whether fueled by CO2 released from consuming fossil fuels or part of a long term cycle, make wildfires more difficult to control. Predicted greater variability in precipitation may weaken our perennial grasses, which form the Thin Green Line that protects the land from both erosion and invasion by cheatgass.

Although we can measure the extent and frequency of fires and the rates of soil loss and deposition after fire, we do not know how many acres can burn and how much soil can blow to the other states before we careen into a downward spiral of unraveling natural systems. Rather than focusing on only our short term goals of production from our Western lands, we must remember to also focus on maintaining the long term function of our lands. We must remember to protect our perennial grasses so that they can protect the land for us.

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