Upper Big Creek NEON / BIGC

Upper Big Creek (BIGC) is an aquatic NEON field site located in central California. It is a wadeable stream on the western slope of the Sierra Nevada Mountains with a watershed size of approximately 10.9 km² (2700 acres). BIGC spans an elevation range of 1003 - 1700 m (3290 - 5580 ft.) and passes through mixed mature cottonwood trees, short grasses, and shrubs. The BIGC catchment is entirely located in the Sierra National Forest. This site is part of the U.S. Forest Service’s Major Land Resource Area (MRLA) 22A – Sierra Nevada Mountains and is within the Southern Sierra Lower Montane Forest ecoregion. It is part of the Pacific Southwest Domain (D17), which is bounded by the Pacific Ocean on the west and the Sierra Nevada Mountains on the east, and encompasses most of California. There are four other NEON field sites in D17, including three terrestrial sites and one additional aquatic site. BIGC is colocated with the NEON terrestrial site Soaproot Saddle (SOAP). [1] [3]

The climate in the Big Creek (BIGC) watershed is considered Mediterranean with warm, dry summers with temperatures ranging from 14-20°C (57-68°F), and mild to moderate wet winters with temperatures ranging from 0-9°C (32-48°F). The annual mean temperature is 13.4°C (56°F). BIGC experiences a mean daily variability in air temperature of approximately 20°C. It is representative of moist sites of the Sierra Nevadas, with annual precipitation averaging 900.35 mm (35.4 in.). It is below the snow-dominated transition elevation with recently decreasing proportions of precipitation falling as snow between December and March. Precipitation is heaviest through the winter months and early spring with summer months being very dry. The bulk of precipitation at this site and elevation falls as rain. [1] [5]

The Big Creek Basin lies in the Sierra Nevada batholith within the southern extent of the Sierra Nevada mountain range. This batholith is comprised mainly of granodiorite and quartz monzonite and was formed approximately 200 million years ago. [1] [4]

Major soil series that are mapped at the colocated terrestrial SOAP site (just south of the aquatic BIGC site) in the Soil Survey of Sierra National Forest Area, California (Giger and Schmitt, 1983) are Holland (Fine-loamy, mixed, semi-active, mesic Ultic Haploxeralfs), Chaix (Coarse-loamy, mixed, superactive, mesic Typic Dystroxerepts), Chawanakee (Loamy, mixed, active, mesic, shallow Typic Dystroxerepts), and Tollhouse (Loamy, mixed, superactive, mesic, shallow Entic Haploxerolls). The soils in the region are poorly formed due to the climate (cold winters, dry summers), the resistance of the granite to weathering, and the removal of eroded material into drainages before further weather and soil formation can occur. Therefore, soils in this region have low horizonation, clay content, and weak structure. Weathering of granite rocks results in runoff with low dissolved solid content and leads to low nutrient waters. [1] [3]

The flow regime of Upper Big Creek (BIGC) is typical of snowmelt-dominated mountainous streams in the West. Base flows are lowest in the winter (November – March) and highest in the late spring (April – June). BIGC has a mean base flow of 10 liters per second in the autumn months. Snow melt begins in March and peaks in April. Discharge during the peak flow month of April is approximately 21 times greater than base flow. [1]

The Upper Big Creek Basin ecosystem is dominated by coniferous forest consisting of ponderosa and sugar pines (Pinus ponderosa and Pinus lambertiana), incense cedar (Calocedrus decurrens), sequoia (Sequoiadendron giganteum), and white fir (Abies concolor). The understory is primarily scrub-shrub. The riparian forest is dominated by cedar, pine, and fir with a small percentage (<1%) of California black oak (Quercus kelloggii), white alder (Alnus rhombifolia), Oregon ash (Fraxinus latifolia), and black and Fremont cottonwood (Populus trichocarpa and Populus fremontii), with an understory of scrub-shrub with ferns and grasses. The riparian forest floor contains much higher amounts of organic matter due to dead-fall, shading, and higher humidity. [1]

BIGC hosts brown trout (Salmo trutta) and rainbow trout (Oncorhynchus mykiss). Native to Europe, Africa, and Asia, brown trout was introduced to California in 1884. Rainbow trout is an anadromous species native to the Pacific coast and coastal states. Other fishes native to the Sierra Nevada include Chinook salmon (Oncorhynchus tshawytscha), California roach (Lavinia symmetricus), hardhead (Mylopharodon conocephalus), prickly sculpin (Cottus asper), and riffle sculpin (Cottus gulosus). The California red-legged frog (Rana draytonii) is a federally-listed threatened species that occurs at BIGC. The western pond turtle (Actinemys marmorata) is a state-listed species of special concern at BIGC. [6] [7] [8] [9] [10]

Upper Big Creek (BIGC) is part of the U.S. Forest Service’s Major Land Resource Area (MRLA) 22A – Sierra Nevada mountains. The area is used for logging, grazing, and recreation, including quail, mule deer, and black bear hunting. BIGC is managed by the High Sierra Ranger Station and Blue Canyon work station, which conduct controlled burns, logging, and herbicide application to manage the forest for timber and livestock production, as well as fire suppression. The Critical Zone Observatory maintains an eddy-covariance flux tower and hydrological monitoring instruments to analyze the carbon and water balance and other atmospheric properties of the forest. [2] [11]

Site characterization for BIGC began in January 2016 and establishment was completed in November 2017. The aquatic instrumentation system (AIS) began streaming in June 2018. The aquatic observation system (AOS) began sampling in July 2018.