Originally created 08/16/97

Nature survives drought

WASHINGTON - When the rains stop, the worms go down, down as far they can. Wheat digs in, its roots 10 feet deep. Buzzards munch watermelon - they are not known to spit out the seeds.

Bold sunflowers swivel their heads from dawn to dusk. Thirsty but unbowed, they stare defiantly back at the sun, tracing its path across a bleached sky.

Drought and dry spells have befallen large stretches of the country. For nature, that means a struggle to survive that runs silent and deep.

Fires have consumed twice as much tinderbox acreage in Maine this year as last. Lawns are brown across the mid-Atlantic. A major lake 70 miles from Phoenix has seen water drop to levels close to danger for its wildlife.

"Here we sit," said Ohio farmer Wilma Mohr, "with our tongues hanging."

Even where it's wet, it can be dry. The Southwest monsoons have come, but they are not enough yet to undo the damage.

For American farming, the saving grace is the law of averages across this vast land.

Despite extreme drought in the Southwest and excessive dryness in parts of the Plains, the Northwest and the East, it's expected to be a good year for grain and not a bad one for several other crops.

Americans generally haven't felt the pinch. Bountiful spring rains and winter runoff brought reservoirs to brimming.

But water in the bank is of no benefit to animals or plants outside the reach of a sprinkler or farm irrigation. It's there that nature is falling back on its own resourcefulness, winning some, losing some.

The struggle goes on above and below: in Virginia mountain forests that crackle underfoot, central grasslands where hairy blades help conserve moisture and Maryland's Chesapeake Bay, where the increased salinity is good for oyster reproduction but encourages disease.

Terrestrial salamanders are escaping down old root channels or rodent burrows into deeper, moist soil. There, they go into a form of hibernation and survive if they've chosen the right depth to slow their metabolism.

"Plants and animals have to deal with this all the time," said Sam Droege, wildlife biologist with the U.S. Geological Survey. "They have strategies. At some point, some run out of strategies."

The dogwood runs out of them sooner than the oak. Its curled leaves betray its stress. Oak is one tough customer, and so is pine.

"It takes a tremendous drought to kill a tree," Droege said. "Usually the tree that dies in a drought is stressed for other reasons."

For birds, the dryness is good for eggs and they can usually fly to water.

The dickcissel, a bird that sings its name, winters in South America and favors tall Plains grasses for nesting but will fly to Eastern pastures if its favored grounds are dry.

Deer will go for the green and anything with a decent set of legs will also move on.

Plants are stuck with putting energy into root growth if they can, and curling, drooping or turning leaves from the sun to limit evaporation. That also reduces their necessary intake of carbon dioxide.

Curled leaves at night may mean imminent death.

"The total quantity of water absorbed by any plant is enormous - far greater than that used by any animal of comparable weight," says the Biology of Plants textbook.

While animals recirculate a lot of water, plants use it and lose it. A corn plant loses 54 gallons in a season; a wheat plant, 25 gallons.

Among desert plants, the evergreen pistache tree penetrates rock by excreting a dissolving acid from its root tip. Mesquite grows a tap root as deep as 200 feet.

And when the soaking rains return?

Chances are, that brown neglected lawn will regenerate. It may end up looking much the same as the lawn tended with untold hours of watering.

The worms that only came close to the surface at night for food make their slimy reappearance, en masse.

And ants that find water at their nest entrance sound the alarm through body vibrations and lay an odor trail for the colony.

"In less than 30 seconds, they can get a nest cleared," Erich Hoyt writes in The Earth Dwellers.

In Southern U.S. floodplains, fire ants faced with rising water form rafts with their bodies to carry the queen and brood away until they can snag the nearest bush or stem.

Most will live to be very busy another day.


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