Covering an area of 295,233 sq. km, the State of Arizona is geographically positioned in the southwestern region of the United States. It is also the 6th largest and the 14th most populous state in the USA. Approximately 15% of the state’s total area is privately managed while the rest of the area is managed as parts of public forests and parks, trust lands, and Native American reservations. The National Park Service, an organ of the US Department of Interior, not only supervises the protection of the US National Parks but also protects all the other US natural and historical heritage sites. In Arizona, there are 24 such sites including the 3 National Parks that are under the management of the National Park Service.
Situated in the southeastern part of the US State of Arizona in Pima County is the Saguaro National Park. The Park occupies an area of 371.16 sq. km and comprises two separate sites: the Tucson Mountain District and the Rincon Mountain District. The Saguaro National Park preserves the flora and fauna of the Sonoran Desert area and is therefore named after the large Saguaro cactus that is native to the Sonoran Desert and the northwestern part of Mexico and is not grown naturally in any other place on the planet.
The Tucson Mountain District covers an area of 10,000 ha and is situated about 16km west of the city of Tucson. The comparatively larger Rincon Mountain District occupies an area of 27,000 ha and is situated about 16km east of the city of Tucson. These two separate districts together with a combined area of 37,116ha make up the Saguaro National Park. Of the total 37,116 ha area of the park, about 29,000 ha has been designated as a “wilderness area”.
Both the Tucson and the Rincon Mountain districts form a part of the Sonoran Desert and are surrounded by the Tucson Mountains in the west and the Rincon Mountains in the east. The Rincon Mountains are taller than the Tucson Mountains and the volcanic rocks that make up the two districts of the park vary significantly. Located in the Rincon Mountain District, the Mica Mountain rises to an elevation of 2,642m and is the highest point in the Rincon Mountains as well as the Saguaro National Park. The Park also includes several springs and creeks.
The Saguaro National Park has a rich geologic history. The oldest rocks found in the park are known as Pinal Schist, which are dark gray metamorphic rocks that are approximately 1.7 billion years old. Extensive volcanic activities and mountain building took place in the area during the Laramide orogeny about 80 million years ago. Volcanic eruptions led to the formation of the Tucson Mountains approximately 70 million years ago. The Tucson Mountains, the Santa Catalina Mountains, and the Rincon Mountains form a part of the Basin and Range Province of the Western United States.
The Saguaro National Park serves as an important tourist destination and attracts numerous visitors annually. There are about 266km of hiking trails in the park and paved roads in the different parts of the park allow sightseeing activities. Bicycling and horseback riding are some of the major recreational activities that are allowed on selected paved areas of the park. The Saguaro National Park remains open for visitors every day from sunrise to sunset.
According to the Köppen climate classification, the Saguaro National Park experiences a ‘hot semi-arid climate’ with hot summers and cool winters. During summer, the daytime temperature rises to 43°C, and the nighttime temperature is about 22°C. During winter, the daytime temperature is about 19°C, while the nighttime temperature drops below 5°C. The Saguaro National Park receives short heavy rains that are often accompanied by dust storms, lightning, and flash floods during the summer season. The higher elevations of the Rincon mountains receive snowfall during winter.
Flora And Fauna
The diverse habitats of the Saguaro National Park support a variety of flora and fauna. Different plant communities are found in the park. The Tucson Mountain District features desert scrub at lower elevations and desert grassland at higher elevations. The Rincon Mountain District features different plants like Ponderosa pine, Gambel oak, Douglas fir, white fir, many shrubs, and understory plants. As per different scientific studies, there are about 197 fungi species, 25 non-vascular plants, and 389 vascular plant species in the Saguaro National Park.
Both the Tucson Mountain District and the Rincon Mountain District of the park feature the native giant saguaro cactus (Carnegiea gigantea). It is estimated that there are about 1.8 million saguaros in the Saguaro National Park. Some 24 species of cactus are also found here including Engelman’s prickly pear, pink flower hedgehog, jumping cholla, fishhook barrel, etc. However, the introduction of invasive plants like tamarisk, buffelgrass, fountain grass, etc poses a significant threat to the native ecosystem of the Saguaro National Park.
About 30 species of mammals are found in the Saguaro National Park. These include white-tailed deer, coyotes, javelinas, black-tailed jackrabbits, gray foxes, desert cottontails, ground squirrels, ring-tailed cats, and the lesser long-nosed bat. 3 amphibian species like Couch’s spadefoot, canyon tree frog, and lowland leopard frog are found here. About 36 species of reptiles including diamondback rattlesnakes, Gila monsters, desert tortoises, spiny lizards, short-horned lizards, etc are found in the Saguaro National Park.
About 107 species of birds are found in the park including the whiskered screech owl, vermillion flycatcher, cactus wrens, woodpeckers, ravens, hummingbirds, hawks, kestrels, and the highly-threatened Mexican spotted owl.
It is believed that the present Saguaro National Park area was inhabited by the Hohokam people from 200 to 1450AD. Petroglyphs made by the Hohokam people have been found on the stones in the Tucson Mountain District. After the Hohokams, other indigenous people such as the Sobaipuri, Apaches, and Tohono O’odham also lived in the area. Eventually, the area was inhabited by Spanish explorers, missionaries, homesteaders, ranchers, and miners. As per recent estimates, there are over 60 historic structures and 450 archaeological sites in the present park area.
In 1920, some members of the University of Arizona’s Natural History Society decided to protect the area for the conservation of the giant Saguaro cactus as well as the biodiversity of the Sonoran Desert. On March 1, 1933, then US President Herbert Hoover proclaimed the area as the “Saguaro National Monument”. In 1961, US President John F. Kennedy added about 6,500 ha of cactus land in the Tucson Mountains to the Saguaro National Monument. The Presidential Proclamation also led to the creation of the Tucson Mountain District in the west and the Rincon Mountain District in the east. On October 14, 1994, the US Congress combined these two separate districts and established the Saguaro National Park.