By Donald Edward McHenry, Junior Naturalist

ONE OF THE outstanding features of the Grand Canyon region is the existence of six of the seven classified climatic life zones found in the world. The only zone not represented here is the tropical. Three of these zones are so evident in the canyon that even the average visitor traveling from rim to rim by trail is easily able to distinguish the differences both by changes in temperature and by the general character of the vegetation.

Unfortunately not every visitor to Grand Canyon is able to cross by trail. In order to show those people who cannot make the trip the kind of plant life growing in the various zones, live plants typical of these places were collected during 1930 and planted in three representative gardens just outside of Yavapai Observation Station on the south rim. One of these gardens features the Canadian Zone (plants living in a climate similar to that of central Canada); another the Upper Sonoran Zone (plants living in a climate similar to that in central United States at sea level); and the third the Lower Sonoran Zone (plants living in a climate similar to that of desert Mexico).

Thousands of visitors to the south rim of Grand Canyon this past summer have shown a great deal of interest in this display of plant life. Probably very few realized the difficulties involved in building up such gardens. In the first place, truck loads of suitable soil had to be hauled to this location. Then there were the plants.

The plants representing the Upper Sonoran Zone were, of course, gathered and grown with comparative ease, for that is the zone in which the gardens are established. In fact, the problem concerning them soon resolved itself into the job of keeping too many individuals from developing from the seeds carried in from the immediate surroundings.

Transferring the plants from the other two zones presented a different and more difficult problem. The Canadian plants could not easily be transported from the north rim; therefore, it was more convenient to bring them from the Canadian Zone on the side of the San Francisco Peaks. Even this involved a distance of more than a hundred miles. It necessitated very careful preparation of the specimens for the journey. That all such plants would live was more than could be expected, consequently the representation in this garden is not inclusive. We hope to be able to get additional plants from the north rim next summer. They will have to be trucked about 230 miles, part way through the Painted Desert.

The plants from the Lower Sonoran Life Zone have presented a problem of even greater difficulty. Some of them were trucked in from the nearby Painted Desert, but others which are found in this region only in the bottom of the canyon could not be obtained in this manner. The writer has tried bringing those plants up the trail in boxes on pack mules. Many difficulties were involved. Often it was hard to inveigle the mule into cooperation while placing the plants in the boxes. Then the motion of the mule walking up the trail tended to work the roots of the plants free from the soil which they so greatly needed for protection against loss of moisture. Again, plants from a lower zone seemed to suffer more by transfer to a higher zone than did plants moved the opposite way. Altogether we consider ourselves fortunate in having many survivors in the Lower Sonoran garden, nevertheless, we will keep on experimenting for we believe that the gardens mean a great deal to our visitors, and represent an important ecological study to us.

Following is a list of the plants which are now growing in the Life Zone gardens: - See also accompanying chart showing the present arrangement.

CANADIAN LIFE ZONE GARDEN

UPPER SONORAN LIFE ZONE GARDEN

LOWER SONORAN LIFE ZONE GARDEN