Sunday, April 7, 2019

Four North American Deserts in a Week

Last week I had the opportunity to visit all four major North American deserts: Mojave, Chihuahuan, Sonoran, and Great Basin. Here's a map from the Arizona-Sonora Desert Museum that shows where they are located:
Image from: http://mojavedesert.net/description.html

Now comes the fun part. Check out the photo and see if you can guess which desert is pictured. Answers are under the photo. Click the links to learn more about that desert. Let's start right away:
This desert is huge, but only a small part is in the U.S., in western Texas and southern New Mexico. It's the Chihuahuan Desert, a hot desert except that it's at a higher elevation, from 1,200 to 6,000 feet, so it's not the hottest in North America. It receives an average of 10 inches of rainfall, the most of the four deserts. The most widespread and dominant species is the creosote bush, which is also common in the other hot deserts. Other common plants are ocotillo. The characteristic plant is the lechuguilla (Agave lechuguilla), usually found in limestone soils. Other agaves, yuccas, and sotols are common. Pictured above is an ocotillo in the background and agaves (maybe lechuguilla?) scattered with grasses. The photo was taken at Carlsbad Caverns National Park. Next up: (hint, this one is a bit of a trick, as it's in a transition zone)
Ocotillo (Fouquieria splendens), the tall spindly, plants, are common not only in the Chihuahuan Desert, but also the Sonoran Desert. The huge cactus is a barrel cactus (not sure which one). This photo is taken on the Ocotillo Trail at Kartchner Caverns State Park, which is in the transition zone of Chihuahuan and Sonoran Deserts. This one should be easy!
Our hottest hot desert is the Sonoran Desert, with their characteristic saguaro cacti (Carnegiea gigantea), which die in a hard freeze that lasts more than 20 hours. Other common plants are littleleaf palo verde (Cercidium microphyllum), ocotillo, ironwood, mesquite, and cholla. Photo taken at Saguaro National Park. Can you also spot the cholla and prickly pear cactus? Only two deserts left. Which one is this?
If you guessed Mojave Desert, you're right! The Mojave Desert is between the Great Basin and Sonoran Deserts and is the smallest of the four deserts. It's also the driest, with an average of 2 inches in the east and 5 inches in the west. It's divided into upper and lower bajadas. In the photo above, taken along Highway 93, you can see creosote bush, common in the lower bajada. Common associates include bur sage, Mojave yucca, banana yucca, and various cacti. The upper bajada is dominated by Joshua trees (Yucca brevifolia), which happened to be in bloom!
That leaves just one desert left, the highest elevation and coldest:
This is the Great Basin Desert, where sagebrush is the dominant shrub. Although some cacti are found in this desert, gray, low shrubs dominate the landscape. Another identifying feature is the Basin and Range Province, with alternating mountains and valleys. In the background in the photo above is Great Basin National Park, a park that is almost entirely in the range, looking out at the basins in adjacent Snake and Spring Valleys. Here's a photo of three of the most common bushes: on the left is tall sagebrush (Artemisia tridentata), in the middle is greasewood (Sarcobatus vermiculatus), which is just starting to leaf out, and on the right is grey rabbitbrush (Chrysothamnus nauseosus). Fun fact: when early settlers were looking for good land to settle for farming, they looked for sagebrush, which showed that the soil had good nutrients, with greasewood nearby, as greasewood depends on groundwater and usually grows where water is within 40 feet of the surface. If they had that combination of water and good soil, they could probably have good crops!
Which of these four deserts have you visited? Do you have a favorite?
More to come on them in the coming days!
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