Desert Appreciation
                     speaker:Thom Hulen
                                    summarized by Fran Wylie

Thom Hulen, Conservation Director of the DFLT (Desert Foothills Land Trust), spoke in one of a series of talks at Terravita March 13, 2003, on the DFLT and on hiking in our desert area. 

He defined a desert as a place where evaporation exceeds precipitation. Phoenix gets about 7-1/2 inches of rain per year providing about 4.2 gallons per square foot. In Terravita, we get about 8.5 gallons of water per square foot which amounts to a 14-inch precipitation rate.  

The Sonoran desert is unique. It is the only place where the saguaro grows. It has two rainy periods per year: the winter rains are characteristically gentle whereas the summer rains tend to be dramatic and sporadic. Plants here have adapted to the environment. They may have small leaves or no leaves. Waxy leaves reduce evaporation. Grey-green leaves reflect light away from the plant. Some plants are adapted to produce food at night; stomatas close in the day and open at night. The indigenous palo verde has chlorophyll on its bark to permit photosynthesis. 

The saguaro serves as an example of cooperation in nature. Ovules are fertilized by pollen. Bats and white-winged doves pollinate the saguaro flowers. White-winged doves also help pollinate the saguaro cactus.  When they feed upon insects in saguaro cactus flowers they transfer pollen from one plant to another. The fruit then becomes available for other animals to ingest and to distribute seeds by various means.  When feeding on the fruit they inadvertently knock off fruit that will be consumed by ground dwelling animals.  

Although mad dogs and Englishman may go out in the sun, animals do not go out in the hot sun. There are more deer in Carefree and Cave Creek than elsewhere in the state. The same is true of javelinas. Some animals are nocturnal. Most mammals such as dogs and rabbits have no sweat glands so they stay in the shade and pant to keep cool. The big ears of jack rabbits help them keep cool. 

When we go hiking, we should plan on providing 1-1/2 gallons of water per hour. We should carry a “letterman,” comb or something similar to remove spines accidentally acquired.  

Good advice regarding threats from snakes, bees, or other predators is to “never put hands or feet where eyes have not first seen.” As for scorpions and tarantulas, shake articles out before using; Thom has never been bitten in 47 years of exposure.

The DFLT property is open to the public as are other preserves. Hikes are led to the cave six times a year because the DFLT has a conservation easement on the property. Thom described caliche as calcium carbonate which is the same mineral that makes limestone. He also spoke of toads: the Red Spotted Toad and the Sonoran Desert Toad (Colorado River Toad). All have poisonous skin glands. When dogs and cats bite or mouth the toad, they foam at the mouth. Thom recommends rinsing the animal’s mouth with water from a hose. American Indians and others have used skins of toads to produce hallucinogenic effects.