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The mean annual temperature for CARI is -3°C (26°F). Mean annual precipitation is 262 mm (10.3 in.), 30% of which can be snowfall. Temperatures can vary widely over the course of a day. The annual temperature variation also spans from -50°C (-58°F) to 33°C (91°F). Generally, precipitation and humidity in the area is low. Below-freezing temperatures can persist from the months of October through April in nearby Fairbanks, Alaska. However, temperature measurements starting in 1981 through the present day show deviations from historic daily average temperatures that are hotter than usual, particularly in winter months. Thawing permafrost in Caribou-Poker Creeks Research Watershed has undergone recordable losses, and is an important research component within the watershed, as are wildfire disturbances. Alaska is affected by climate change patterns, with around 2.5°C (4.5°F) of warming experienced since around 1948. [2] [3] [5] [8]

Birch Creek Schist is the dominant bedrock type at CARI. Quartzite is also found here, and aeolian silts derived from the Tanana Flats overlay the area. [4] [19]

Soils within CARI are typically silty alluvium and colluvium materials, with layers of permafrost on the surface. Gilmore silt loam, Typic Cryochrepts, and Histic Pergelic Cryaquepts are some of the major soil types within the site. The soils within CARI are affected by the cycle of ice thawing and freezing, resulting in cryoturbation (mixing of materials from various soil horizons down to the bedrock). [4]

The Caribou-Poker Creeks Research Watershed is characterized as a typical upland headwater stream basin in subarctic Alaska. Snowmelt is crucial to the flow of Caribou Creek, with winter freezing stopping flow through the system and peak flow during the spring. Caribou Creek’s channel is 1 - 5 m (3 - 16 ft.) wide. During peak melt times, the discharge in Caribou Creek can reach upwards of 1000 liters per second. Key hydro-biological research topics conducted in CPCRW include how permafrost thaws and how wildfires affect fresh water stream ecology. [2] [18]

The CARI area contains areas of permafrost, hardwood forest, wetlands, and shrublands. Moss covers patches of permafrost throughout the Caribou-Poker Creeks Research Watershed area. The hydrology and drainage of the area influences dominant vegetation types, with areas of poor drainage dominated by moss, sedge, and shrub species. Evergreen forest constitutes the majority of land area within the site. Black spruce (Picea mariana), lingonberry (Vaccinium vitis-idaea), and bog Labrador tea (Ledum groenlandicum) are some dominant species. Alder, willow, and dwarf birch around 2 - 3 m (6 - 10 ft.) tall grow directly along the banks of the Caribou Creek channel. Moss, lichen, blueberry, willow, and shrubs grow along the channel as well, and some black spruce trees can be found in the area. [1] [20]

Some of the fish found in the Caribou Creek include slimy sculpin (Cottus cognatus) and Arctic grayling (Thymallus arcticus). Macroinvertebrates in Caribou Creek include small minnow mayflies (Baetis bicaudatus), midges (Eukiefferiella), flathead mayflies (Cinygmula), and detritus worms (Naididae). [11]

The Caribou-Poker Creeks Research Watershed was established in part to address the need to study Alaskan hydrological processes. The city of Fairbanks, AK flooded in 1967, leading to increased attention toward hydrology in the area. In 1969, the Inter-Agency Technical Committee for Alaska established the Caribou-Poker Creeks Research Watershed, an area representative of subarctic hydrological conditions. Eventually, the Caribou-Poker Creeks Research Watershed became managed as a part of the Bonanza Creek Long-Term Ecological Research site, which was established in 1987.

Levels of human activity in the watershed have changed multiple times in the past century. The land around the Caribou-Poker Creeks Research Watershed is traditionally the territory of the Tanana people. Historically, Tanana people formed nomadic family groups that traveled along the Tanana River. The arrival of Euro-Americans in the region caused upheaval in their way of life; however, Tanana people today remain connected to the region around the Tanana River. From approximately 1905 - 1930, there was some resource-extractive economic activity by Euro-American settlers. By 1940 - 1970, mineral prospecting and logging was not prevalent in the area. There is evidence that the 1901 arrival of prospectors in the area of the Caribou-Poker Creeks Experimental Watershed affected the landscape. A study of historical fires in the Caribou-Poker Creeks Experimental Watershed revealed that the watershed experienced a series of fires between 1896 and 1925, which the study authors noted coincided with the historical period of prospecting and mining in the area, suggesting some of these fires may have originated in human activity. More recently, the watershed experienced a fire in 2004. [1] [12] [13] [14] [15] [16] [17]

The NEON CARI site lies within the Caribou-Poker Creeks Research Watershed (CPCRW), which is a watershed within Bonanza Creek LTER, an area managed for scientific study by the University of Alaska. Scientific research is the only human activity currently being conducted in the CPCRW. Scientific data has been collected in CPCRW from as far back as the 1970s. Encompassing 104 km² (25,700 acres), the CPCRW provides a valuable area for researchers to study how watersheds are influenced by wildfires, discontinuous permafrost, and climate change. In particular, climate change-driven risk of wildfires is a management concern that Bonanza Creek LTER that researchers have worked to better understand with the help of indigenous communities and fire managers. The Working Group on Rural Alaska Self-Reliance was formed with Bonanza Creek LTER researchers and Alaskan indigenous leaders to address management strategies to sustain ecological and social livelihoods in the face of climate change. [1] [2] [9] [10]

Sampling readiness review for CARI was completed in June 2017. Aquatic observation systems were established in September 2016, and aquatic instrumentation systems were established in October 2017. During the construction of wells and other infrastructure, minimally invasive infrastructure was preferred. Likewise, to minimize disturbance to the site during maintenance and data collection, paths, boardwalks, and foot bridges were planned along the site. Due to the yearly freezing of Caribou Creek, aquatic sensors are removed to prevent damage in the winter. [1] [2] [20]