Habitats of the Llano Estacado
Sanddunes
Photoessay: Yoakum County, January 2007
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The sandyland of Yoakum County has been "broken out" for farms in past years. This old field is now revegetated with little bluestem (the reddish grass in the picture.) A few splotches of snow remain from a storm the week before.
In the same field, the "navaho blanket" appearance of the colorful grasses go as far as the eye can see.
The green is the "endemic" (native to one small region of the world) Cory Ephedra. Its range is confined to the Llano Estacado. Use the website search engine to find out where else the staff of the Sibley Nature Center has seen the species. The gray shrubs are leafless sand sage, a sanddunes habitat specific species of shrub. In the distance is a patch of the whitish seedstalks of sand dropseed grass.
Even vegetated sanddunes move over time. The concrete poured for this corner post is now above ground. In the foreground are the tawny mounds of three-awn grass. In the background snow on the north side of the dunes is also shaded by the shinoak shrubs.
Three mule deer stayed in a swale between shinoak covered dunes where they had sought protection from the wind. The one on the left lost half of her ears - most likely to freezing temperatures when it was a newborn fawn.
Some of the shinoaks had more of last year's leaves on them. Was this due to genetics, or protection from cold winds?
A closeup inspection of the snow on the ground reveals two peculiarities. Notice the little ridges in the sand where the evaporating and melting snow clumped the sand grains. Leaves, sticks, and other objects heat up and cause the snow to melt near them, leaving little circles in the snow.
Feral hogs moved into the Yoakum County sand dunes in 2000, according to a local rancher. This small group stayed in "plain view," while another 20 or more found a quicker route out of sight.
Shinoak lines the top of this snow covered dune. A feral hog's track leads up and over the center of the dune.
Some biologists believe that the sandy lands once burned every five years. The fires were started by lightning, or by American Indians rejuvenating the grass and forage for the pronghorn and other wildlife. (click here to read a story about prairie chickens and fire.) The windmill marks a well that gets good water from the Ogallala Formation at a depth of around 160 feet.
In a larger swale between dunes little sand is present. Along the edge of an old stocktank, an observer notes that the red clay is only about two feet deep, and below it is white caliche rock. The tree is an old chinaberry. This might indicate that at one time a ranch house was also on the site.
It is very tricky driving on roads in the region after a snow. The saturated surface is incredibly slick. The SUV was in 4-wheel drive, and its forward movement occurred while the vehicle was at a 45 degree angle to the road.