he results from an upcoming Environmental Assessment (ea) will determine the fate of countless tamarisk this summer. The plan is to remove the tamarisk from ten acres around Lees Ferry and plant willows and cottonwoods in their place, creating a lovely vision of a cozy put-in with lots of excellent shade. Also included in the three year re-vegetation program (funded by a proposed $370,000 grant from the Arizona Water Protection Fund) is a project to remove the tamarisk from 63 Grand Canyon tributaries. The Lees Ferry project will determine the feasibility of restoring a dozen areas along the Colorado River corridor through Grand Canyon to a pre-dam cottonwood/willow forest condition. Greg Woodall eloquently discussed the project with gts participants at mile 145, which coincided with an inspirational down-river view of the Olo Canyon cottonwood at the river's edge, shining in the beautiful morning light streaming through the side canyon.
Tamarisk have been studied extensively since their migration to the Colorado Plateau many years after their introduction to the us in the 1800s. They were even promoted in some areas of the West in the 1930s to provide erosion control for a landscape already stressed by wasteful agricultural practices. Though some biologists consider tamarisk naturalized, they are defined as non-native in the Grand Canyon. I recall displaying my own ignorance of the issues of non-native biota during the Fall 1999 gcrg meeting in Kanab. After a speaker explained the issues of eradicating camelthorn in the Canyon and the unpleasant mess they create for camping at beaches, I asked him if there had been any camelthorn habitat studies of insects and birds. After hearing that habitat wasn't the main issue, I wondered aloud if possibly plants like the camelthorn could offer habitat to species not seen since the pre-dam era and finished with the statement, “perhaps we should trust Mother Nature—she knows best.” Needless to say, my comments were not considered further, and the discussion moved to the more practical aspects of non-native plant removal.
It seems impossible for us to fully understand the complexity of the Grand Canyon ecosystem. We are reminded of this by Aldo Leopold's discussion of the “Land Pyramid” from A Sand County Almanac:
“Plants absorb energy from the sun. The energy flows through a circuit called the biota, which is represented by a pyramid consisting of layers. The bottom layer is the soil. A plant layer rests on the soil, an insect layer on the plants, a bird and rodent layer on the insects, and so on up through various animal groups to the apex layer, which consists of the larger carnivores.”
“Each successive layer depends on those below it for food and often for other services, and each in turn furnishes food and services to those above. Proceeding upward, each successive layer decreases in numerical abundance. Thus, for every carnivore, there are hundreds of his prey, thousands of their prey, millions of insects, uncountable plants.”
“The lines of dependency for food and other services are called food chains. The pyramid is a tangle of chains so complex as to seem disorderly, yet the stability of the system proves to be a highly organized structure. Its functioning depends on the cooperation and competition of its diverse parts.”
Reinforcing Leopold's ideas of the complexity of nature is the case of the endangered willow flycatchers, which have found suitable nesting grounds in tamarisk. As published in the Southwest Naturalist (June 1989), Bryan Brown and Michael Trosset found that tamarisk composed a substantial part of the nesting habitat used by the willow flycatchers, despite the range of nesting habitat (including willows) available to them but presently unoccupied. Steve Carothers writes further on the insect habitat tamarisk offers: “...the actual biomass of insect productivity can be greater on the tamarisk than on the willow. Willows may have a richer, more diverse insect fauna, but tamarisk can produce spectacular outbreaks of leafhoppers.” (The Colorado River Through Grand Canyon, 1991, p.141) With all the complexity in the changing ecosystem, it seems impossible to understand the connection of all the biota in the Grand Canyon. With this in mind, could our selective horticultural efforts now create continued future management obligations, similar to how the naive Forest Service fire policies of the early 20th century have necessitated ongoing vigilant fire maintenance? Allowing natural processes to prevail (such as allowing lightning fires to take their course) in a place like the North Rim in its humanly altered state could result in wholesale (and unnatural) devastation of the region. Just as a forest evolves with essential “bridge” species taking root between stages, perhaps non-native plants in the Grand Canyon will provide a stable ecological niche for important plant, insect, and animal species in the future.
The Wilderness Act defines wilderness as a place which is protected and managed so as to preserve its natural conditions, but it is possible to interpret the term “natural conditions” as allowing natural processes to prevail. The effects of the Glen Canyon Dam are becoming understood, but how the ecosystem continues to respond to the radical change in its conditions can only be studied and observed. Allowing it to find its own equilibrium without additional intervention offers us a beautiful opportunity see Mother Nature's natural adaptive processes taking place rapidly. It offers insight on the process of evolution at its finest. Let us enjoy the dance of life in the Grand Canyon as it evolves naturally. Affect it as little as possible. We can't improve on Mother Nature. Let the tamarisk, ravenna grass, Russian olive, and even the prickly camelthorn, grow!
Information on the upcoming ea and the dates of the thirty-day comment period can be obtained by the Grand Canyon revegetation crew at (520) 638-7857, (pob 129, Grand Canyon, az 86023) or the Grand Canyon Wildlands Council at (520) 556-9306.

John Middendorf