RCCZO -- Nutrient Fluxes, Soil Biogeochemistry, Stream Water Chemistry -- Soil Properties, Nutrient Dynamics, Streams -- Arizona, USA -- (2010-2014)

Ephemeral and intermittent streams are increasing with climate and land use changes, and alteration in stream water presence or flow duration will likely affect soil nutrient dynamics in channel and riparian zones more than dryland uplands. To investigate the influence of varying climate and stream flow regimes on associated soil nutrient dynamics, we monitored soil moisture and nutrient dynamics over an 18-month period across a range of ephemeral to seasonally- intermittent stream reaches (13) and landscape positions (channel, riparian, upland) in Arizona, USA. The monitoring reaches were located in largely undisturbed military facilities, long term ecological research areas and a nature preserve. The most arid study washes, Black Gap (BG) and Sauceda Wash (SW), were located within the Barry M. Goldwater Air Force Base near Gila Bend, Arizona in the Lower Gila River Basin. Two semi-arid study washes were located on the Santa Rita Experimental Range near Sahuarita, Arizona in the Santa Cruz River Basin (SS and SR). Nine study sites were located on the Huachuca Mountains near Sierra Vista, Arizona and form part of the San Pedro River Basin. The study sites were located along 3 distinct elevations in 3 canyons: Huachuca Canyon and Garden Canyon which are located within the Fort Huachuca Army Post; and Ramsey Canyon, within the Nature Conservancy’s Ramsey Canyon Preserve. We established three cross-sectional transects 100 m apart at each reach, except Sauceda and Black Gap Washes, where there were 5 transects. We measured soil physio-chemical characteristics including bulk density, particle size distribution, % carbon (C) and nitrogen (N) and isotopes. We monitored seasonal soil moisture, soil exchangeable N and phosphorus pools and N transformation rates using both soil extractions and incubations, wet up experiments, as well as in-situ ion exchange resin bags. Site description and soil data are available over an 18 month period and can be associated with decomposition data and streamflow data sets.