High Desert (Oregon)


The Oregon High Desert is located in the southeast of the U.S. state of Oregon, east of the Cascade Range and south of the Blue Mountains. The desert covers most of five Oregon counties and averages in altitude. The northern region is part of the Columbia Plateau, where higher levels of rainfall allow the largest industry on private land to be the cultivation of alfalfa and hay. The southwest region is part of the Great Basin and the southeast is the lower Owyhee River watershed. The U.S. Bureau of Land Management owns most of the region's public land and manages more than including five rivers designated as Wild and Scenic.
Compared to Western Oregon, the high desert is arid, averaging of annual rainfall. Contrary to its name, most of the high desert is not dry enough to truly qualify as desert, and ecologically, most of the region is classified as shrubland or steppe.
At above sea level, the summit of Steens Mountain is the highest point in the high desert. The broad fault-block mountain is characteristic of the basin and range plate tectonics of the high desert. About 16 million years ago, during the early Miocene epoch, lava flows from volcanic eruptions covered about half the surface area of Oregon. The Earth's crust then began stretching, giving way to further volcanic activity from 15 million to 2 million years ago. Several ice ages over this time formed the large lakes in the high desert.
The climate of the high desert provides habitat for mammals such as pronghorn, coyote, mule deer, black-tailed jackrabbit, and cougar. Birds common in the region include sage-grouse, California quail, and prairie falcon. The western juniper is the most common tree in the region, and big sagebrush and common woolly sunflower are the region's most widespread plants.

Geography

The high desert of Oregon is located in the central and southeastern parts of the state. It covers approximately, extending approximately from central Oregon east to the Idaho border and from central Oregon south to the Nevada border. Most of the region is located in Crook, Deschutes, Harney, Lake, and Malheur counties.
The high desert is named as such for its generally high elevation, averaging about across the region. It is bordered by the eastern foothills of the Cascade Range to the west. The Blue Mountains are the geographical boundary to the north, marking the northern end of the high desert's semi-arid plateau. The southern high desert is part of North America's Basin and Range Province, which extends south through Nevada and Arizona and into Mexico. It contains large alkali lakes and tall cliffs, some with a prominence of more than. Steens Mountain, in Harney County, is the highest point within the region; its summit is above sea level. To the east, the high desert country of the Columbia Plateau extends across the Snake River and into Idaho.
A number of rivers flow through the high desert region. These include the Deschutes River and its tributary the Crooked River, as well as the Malheur, Owyhee, and John Day rivers, which are all within the Columbia River watershed. Because the high desert encompasses the portion of the hydrographic Great Basin located in Oregon, smaller rivers in the high desert flow into closed basins. The Chewaucan River, the Donner und Blitzen River, and the Silvies River each flow into some of the high desert's salt lakes.

Land use

The largest landowner in eastern Oregon is the U.S. government. The Bureau of Land Management administers over in the bureau's Burns, Lakeview, Prineville, and Vale districts, most of which are in the state's high desert country. In addition, Congress has designated specific sections of the Crooked, Deschutes, Donner und Blitzen, Malheur, and Owyhee rivers as part of the National Wild and Scenic Rivers System.
Agriculture is the largest industry in the region. Livestock ranches utilize large tracts of private and government land for grazing. Ranchers raise cattle and sheep in many parts of the region. Because of low rainfall, most crops require irrigation. Agricultural crops include alfalfa and other hay crops, wheat, oats, barley, potatoes, onions, sugar beets, and mint.

Geology

Between 17 and 15 million years ago, magma from deep beneath eastern Oregon rose to the Earth's surface, causing a period of significant volcanic activity. A series of lava floods erupted from fissures near the Oregon–Idaho–Washington border. The resulting lava flows traveled up to from their source. Some individual flows covered as much as to a depth of. Eventually, these lava flows covered half the state of Oregon, creating a formation known as the Columbia River Basalt Group, the geologic foundation beneath much of the high desert.
After the original eruptions subsided, the Earth's crust began to stretch and crack. Between 15 and 2 million years ago, this created hundreds of new volcanoes that added additional layers of lava on top of the Columbia River Basalt and left behind hundreds of lava tubes. These new flows blanketed the southeastern third of the state. Many of the volcanoes and smaller cinder cones from this period still exist in eastern Oregon. Afterward, subsequent rifting produced large fault-block mountains throughout the region. The escarpment-type mountains and high-elevation valleys created by these faults produced the basin and range landscape that makes up much of Oregon's high desert country.
During the last 2 million years, a series of ice ages altered the landscape. As each ice sheet melted, runoff and increased rainfall filled many of the region's closed basins, forming large pluvial lakes. The Goose Lake, Harney, and Klamath basins were filled along with many other smaller basins. Some of the lakes covered as much as. However, as the climate became drier, these large lakes shrank away. Goose Lake, Harney Lake, Malheur Lake, Summer Lake, Lake Abert, and the Warner Lakes are remnants of ancient pluvial lakes.

Climate

Contrary to its name, most of the high desert is not dry enough to truly qualify as desert, and biologically, most of the region is classified as shrubland or steppe.
Annual precipitation throughout Oregon's high desert region is relatively low, averaging less than in most areas. Bend, the region's largest city, averages about of precipitation per year. Burns averages about of precipitation annually, while Rome, in central Malheur County, and the official weather station at Whitehorse Ranch in southeastern Harney County average per year and the Alvord Desert receives only. Some of the mountainous areas receive significantly more precipitation as snowfall. For example, the high-elevation city of Lakeview has an average annual snowfall of nearly.
The majority of high desert areas receive most precipitation in the winter months, decreasing steadily through late summer into the fall. Some areas in the eastern and southern parts of the region receive peak precipitation in the late spring and early summer. For example, at Hart Mountain in Lake County, the wettest time of the year is March through June. The driest months throughout Oregon's high desert are July through September, though there are still isolated thunderstorms during that period.
CityJanFebMarAprMayJunJulAugSepOctNovDecAnnual
Max/Min		Citation
Bend40/2344/2551/2757/3065/3673/4181/4681/4672/3962/3246/2840/23102 / -24
Burns35/1440/1949/2557/2966/3675/4185/4684/4475/3562/2645/2135/15102 / -28
Lakeview39/2142/2448/2856/3265/3874/4484/5583/4875/4263/3346/2639/21102 / -20
Prineville42/2148/2454/2561/2869/3477/4086/4386/4278/3566/2949/2542/21107 / -34

Ecology

The Oregon Badlands Wilderness, east of Bend, has vegetation typical of the high desert region. The native plants are adapted to survive on less than of rain per year. The area is dominated by big sagebrush and rabbitbrush along with hardy grasses like Idaho fescue, bluebunch wheatgrass, and bunchgrass. In the spring, there are native wildflowers such as yellow Oregon sunshine, dwarf purple monkeyflower, sulfur buckwheat, Indian paintbrush, and mariposa lilies. Other high desert wildflowers common throughout the region include buttercups, larkspur, phlox, primroses, and coral mallow. The Oregon Badlands Wilderness also contains the oldest known tree in Oregon, a western juniper estimated to be more than 1,600 years old.
Hundreds of animal species are found in Oregon's high desert environment. In the Hart Mountain National Antelope Refuge alone, there are over 300, including 239 bird species and 42 mammals. Throughout the high desert region, mule deer, pronghorn, coyotes, American badgers, and black-tailed jackrabbits are common. Elk, bighorn sheep, cougars, bobcats, gray foxes, red foxes, North American porcupines, and North American beavers are also found in some parts of the high desert.
Smaller mammals native to the area include long-tailed weasels, woodchucks, cottontail rabbits, pygmy rabbits, golden-mantled ground squirrels, antelope squirrels, Townsend's ground squirrels, yellow-pine chipmunks, Ord's kangaroo rats, and northern pocket gophers. Mice species include Great Basin pocket mouse, northern grasshopper mouse, western harvest mouse, deer mouse, meadow mouse, and creeping vole. There are also numerous bat species that live in Oregon's high desert country.
Common high desert birds include sage-grouse, quail, and sage thrasher. Near high desert lakes and in riparian areas, there are American dusky flycatchers, yellow warblers, orange-crowned warblers, house wrens, spotted towhees, Brewer's blackbirds, western meadowlarks, swallows, and nighthawks. Mountain chickadees, Cassin's finches, black-headed grosbeaks, green-tailed towhees, yellow-rumped warblers, MacGillivray's warblers, mountain bluebirds, common ravens, northern flickers, and white-headed woodpeckers are common in parts of the region. Birds of prey include owls, hawks, prairie falcons, golden eagles, and bald eagles.
Several snakes can be found here, including the Great Basin rattlesnake, Great Basin gopher snake, Northern Rubber Boa, and the Striped whipsnake. Lizards that can be found here include the Desert collared lizard, Western fence lizard, Long-nosed leopard lizard, and the Desert horned lizard. There are no turtles or tortoises native to this area.
Common amphibians in the area include the Pacific tree frog and the Great Basin spadefoot toad. There are no native salamanders or newts to this area.
This area is home to several species of arachnids, including the Northern scorpion, Western black widow, and the banded garden spider.