SOUTHERN CALIFORNIA’S ENVIRONMENT At the Crossroads : Wildlife: <i> VEGETATION, ANIMALS AND HABITATS</i> : Development Destroys River’s Forests

For most of the 1,400-mile journey from its beginnings in the snowcapped slopes of the Rocky Mountains to the Gulf of California, the Colorado River slashes its way through sun-blanched plateaus and deserts almost devoid of the trees and greenery common to other major rivers in the country.

But journals left by settlers around the turn of the century suggest that it was not always this way. The writings tell of dense canopies of cottonwood, willow, mesquite and paloverde trees up to three miles wide on both banks of the chocolate-colored river.

The forests were nourished by natural flood cycles that scoured the undergrowth of debris and potentially toxic salt deposits flowing off local farmlands. The floods also distributed seeds and prepared the soil for new generations of vegetation needed by a variety of insects, birds, mammals and fish.

The main predator along the river was a slim black, white and chestnut-colored hawk. Although never plentiful in California, the Harris’ hawk once soared the length of the river, feeding primarily on rabbits, quail, snakes and lizards.

But now the hawk, the trees and most of the birds and fish are gone--victims of agricultural clearing, commercial development and dam and irrigation systems that destroyed the vast but delicate forests of the lower Colorado River.

What remains of the ravaged riparian habitat contains levels of salt so high that most native trees cannot regerminate, according to biologists and conservationists fighting to restore this once-lush biological reservoir.

The situation is so bleak that proposals for scientifically controlled restoration projects can, at best, aim at growing trees that would last only through their life cycle. All the trees still would need to be replaced by planting new ones, said biologist Bertin Anderson, who has studied the worsening problem since 1973.

A 1987 survey found only 13 stands of cottonwood worthy of being classified as groves along the 250-mile stretch of the river between Davis Dam and the Mexican border.

“It’s pretty grim out here,” said Anderson, who planted an experimental grove of cottonwoods about 20 miles south of Blythe in 1978. That stand remains the largest between Blythe and Yuma.

“We’ve lost 90% of the cottonwoods and willows along the lower Colorado River,” Anderson said. “About 60% of the soil they used is no longer suitable at all.”