Joshua Tree National Park

Joshua Tree National Park is an American national park in southeastern California, east of San Bernardino and Los Angeles and north of Palm Springs. It is named after the Joshua trees (''Yucca brevifolia'') native to the Mojave Desert. Originally declared a national monument in 1936, Joshua Tree was redesignated as a national park in 1994 when the U.S. Congress passed the California Desert Protection Act. Encompassing a total of – slightly larger than the state of Rhode Island – the park includes of designated wilderness. Straddling San Bernardino and Riverside Counties, the park includes parts of two deserts, each an ecosystem whose characteristics are determined primarily by elevation: the higher Mojave Desert and the lower Colorado Desert. The Little San Bernardino Mountains traverse the southwest edge of the park.

History

Early

The earliest known residents of the land in and around what later became Joshua Tree National Park were the people of the Pinto Culture, who lived and hunted here between 8000 and 4000 BCE. Their stone tools and spear points, discovered in the Pinto Basin in the 1930s, suggest that they hunted game and gathered seasonal plants, but little else is known about them. Later residents included the Serrano, the Cahuilla peoples. All three lived at times in small villages in or near water, particularly the Oasis of Mara in what non-aboriginals later called Twentynine Palms. They subsisted largely on plant foods supplemented by small game, amphibians, and reptiles while using other plants for making medicines, bows, arrows, baskets, and other articles of daily life.

A fourth group, the Mojaves, used the local resources as they traveled along trails between the Colorado River and the Pacific coast. In the 21st century, small numbers of all four peoples live in the region near the park; the Twentynine Palms Band of Mission Indians, descendants of the Chemehuevi, own a reservation in Twentynine Palms.

In 1772, a group of Spaniards led by Pedro Fages made the first European sightings of Joshua trees while pursuing native converts to Christianity who had run away from a mission in San Diego. By 1823, the year Mexico achieved independence from Spain, a Mexican expedition from Los Angeles, in what was then Alta California, is thought to have explored as far east as the Eagle Mountains in what later became the park. Three years later, Jedediah Smith led a group of American fur trappers and explorers along the nearby Mojave Trail, and others soon followed. Two decades after that, the United States defeated Mexico in the Mexican–American War (1846–48) and took over about half of Mexico's original territory, including California and the future parkland.

Post-1870

In 1870, white settlers began grazing cattle on the tall grasses that grew in the park. In 1888, a gang of cattle rustlers moved into the region near the Oasis of Mara. Led by brothers James B. and William S. McHaney, they hid stolen cattle in a box canyon at Cow Camp. Throughout the region, ranchers dug wells and built rainwater catchments called "tanks", such as White Tank and Barker Dam.

In 1900, C. O. Barker, a miner and cattleman, built the original Barker Dam, later improved by William "Bill" Keys, a rancher. Grazing continued in the park through 1945. Barker Dam was added to the National Register of Historic Places (NRHP) in 1975.

Between the 1860s and the 1940s, miners worked about 300 pit mines, mostly small, in what later became the park. The most successful, the Lost Horse Mine, produced gold and silver worth about $5 million in today's currency. Johnny Lang and others, the original owners of the Lost Horse Mine, installed a two-stamp mill to process ore at the site, and the next owner, J.D. Ryan, replaced it with a 10-stamp steam-powered mill. Ryan pumped water from his ranch to the mill and cut timber from the nearby hills to heat water to make steam. Most of the structures associated with the mine fell apart, and for safety reasons the National Park Service plugged the mine, which had collapsed.

The Desert Queen Mine on Keys' Desert Queen Ranch was another productive gold mine. In the early 1930s, Keys bought a gasoline-powered two-stamp mill, the Wall Street Mill, and moved it to his ranch to process ore. The ranch and mill were added to the NRHP in 1975 and the mine in 1976. Some of the mines in the park yielded copper, zinc, and iron.

Protection

On August 10, 1936, after Minerva Hoyt and others persuaded the state and federal governments to protect the area, President Franklin D. Roosevelt used the power of the 1906 Antiquities Act to establish Joshua Tree National Monument, protecting about . In 1950, the size of the park was reduced by about to open the land to more mining. The monument was redesignated as a national park on October 31, 1994, by the Desert Protection Act, which also added . In 2019, the park expanded by under a provision included in the John D. Dingell, Jr. Conservation, Management, and Recreation Act.

The Mojave Desert Land Trust (MDLT) has conserved within the park. These inholdings were private ownership within the national park that they were able to purchase. They also acquire private properties bordering federally protected properties. MDLT has sold of acquired private property to the national park service which is more than any other similar organization.

Geography

Potential natural vegetation

According to the A. W. Kuchler U.S. Potential natural vegetation types, Joshua Tree National Park has two categories, a creosote bush potential vegetation type with a desert shrubland potential vegetation form in most of the area, and a juniper/pinyon pine potential vegetation type with a Great Basin montane forest/southwest forest potential vegetation form on the higher elevations of the western side of the park.

Mojave Desert

''See main article:'' Mojave Desert

The higher and cooler Mojave Desert is the special habitat of ''Yucca brevifolia'', the Joshua tree for which the park is named. It occurs in patterns from dense forests to distantly spaced specimens. In addition to Joshua tree forests, the western part of the park includes some of the most interesting geologic displays found in California's deserts. The dominant geologic features of this landscape are hills of bare rock, usually broken up into loose boulders. These hills are popular among rock climbing and scrambling enthusiasts. The flatland between these hills is sparsely forested with Joshua trees. Together with the boulder piles and Skull Rock, the trees make the landscape otherworldly. Temperatures are most comfortable in the spring and fall, with an average high/low of , respectively. Winter brings cooler days, around , and freezing nights. Snows occur occasionally at higher elevations. Summers are hot, over during the day and not cooling much below until the early hours of the morning.

Joshua trees dominate the open spaces of the park, but in among the rock outcroppings are piñon pine, California juniper (''Juniperus californica''), ''Quercus turbinella'' (desert scrub oak), ''Quercus john-tuckeri'' (Tucker's oak), ''Quercus cornelius-mulleri'' (Muller's oak), '' Cylindropuntia chuckwallensis'' (chuckwalla cholla), and ''Opuntia chlorotica'' (dollarjoint pricklypear).

These communities are under some stress, however, as the climate was wetter until the 1930s, with the same hot and dry conditions that provoked the Dust Bowl affecting the local climate. These cycles were nothing new, but the original vegetation did not prosper when wetter cycles returned. The difference may have been human development. Cattle grazing took out some of the natural covers and made it less resistant to the changes.

There are fewer Joshua tree seedlings surviving in the park. It is forecasted that by 2099, under the high emission scenario, the park will increase in temperature by 8 °F. This would make most of the national park unsuitable for Joshua tree growth. Under the low emission scenario, 80% of suitable Joshua tree habitat could be lost.

The desert tortoise population has decreased due to habitat loss and climate change. Lizards in the park are also at risk. Bird species have declined 43% according to studies conducted in 1908–1968 and 2013–2016.

Colorado Desert

Below , the Colorado Desert encompasses the eastern part of the park and features habitats of creosote bush scrub, ocotillo, desert saltbush, and mixed scrub including yucca and cholla cactus (Cylindropuntia bigelovii). Some areas of such cactus are dense enough to appear as natural gardens. The lower Coachella Valley is on the southeastern side of the park with sandy soil grasslands and desert dunes.

The only palm native to California, the California fan palm (''Washingtonia filifera''), occurs naturally in five oases in the park, rare areas where water occurs naturally year-round, and all forms of wildlife abound.

Invasive Species

Invasive plants, such as cheat grass and red brome, contribute to the worsening of wildfires. During wetter periods fills in below and among the pines and oak. In drier times, they die back but do not quickly decompose. This makes wildfires hotter and more destructive, which kills some of the trees that would have otherwise survived. When the area regenerates, these non-native grasses form a thick layer of turf that makes getting a roothold harder for the pine and oak seedlings.

Fountain grass was introduced to the park in the 1990s. This grass competes with native grasses for water and nutrients.

Climate

According to the Köppen climate classification system, Joshua Tree National Park has a hot desert climate (''BWh''). According to the United States Department of Agriculture, the plant hardiness zone at the Cottonwood Visitor Center at 3081 ft (939 m) elevation is 8b, with an average annual extreme minimum temperature of .

Joshua Tree is becoming hotter and drier due to climate change. From 1895 to 2016 the annual precipitation has dropped by 39% and the annual temperature has increased by 3 °F. Because of the hotter and drier conditions, there are more wildfires in the park.

Geology

The park's oldest rocks, Pinto Gneiss among them, are 1.7 billion years old. They are exposed in places on the park's surface in the Cottonwood, Pinto, and Eagle Mountains. Much later, from 250 to 75 million years ago, tectonic plate movements forced volcanic material toward the surface at this location and formed granites, including monzogranite