---TITLE: Toolik Mineral Nutrition ---AUTHORS: -Jeff Welker (PI), Jace Fahnestock (co-PI) -Natural Resource Ecology Lab, Colorado State University, Fort Collins, CO 80523-1499 -tel. 970-491-1796; fax 970-491-1965; e-mail jwelker@nrel.colostate.edu, jace@nrel.colostate.edu ---DATA SET OVERVIEW: -This data represents long-term (1994-2001) carbon and nitrogen dynamics of leaves of dominant arctic plant species in dry heath (61.43N 39.44E) and moist tussock tundra (61.41N 39.42E) near Toolik Lake, Alaska, under ambient environmental conditions and various experimental climate change scenarios. Experimental climate change scenarios have been implemented at these sites since the fall of 1995. The first climate change scenarios is an increase in wintertime snow accumulation that is achieved through the use of a 60 m long by 3 m tall snowfence, built in 1994 at each site. This fence increases wintertime snow accumulation in drifts on the lee side of the fence. The snowdrift is approximately 60 m long, 15 m wide, and 3 m deep at its deepest point. Ambient snow accumulation ranges from a few cm to 60 cm. The second climate change scenario is increased growing season air and soil temperatures (in place since fall 1995). This is accomplished by setting out multiple 1 m2 open-topped chambers (OTCs) over Dryas integrifolia clones in the dry site and Eriophorum vaginatum tussocks in the moist site. These OTCs are hexagonal in shape and are constructed of transparent fiberglass. They typically raise air and soil temperatures by 1 to 4°C. The third climate change scenario at this site is a combination of the first to whereby winter snow accumulation and summer temperatures are both increased. -The data set shows C and N content of leaves of dominant species in dry heath and moist tussock tundra under the four climate change scenarios (ambient snow with ambient temperatures = -S-T; increased snow with ambient temperatures = +S-T; ambient snow with elevated temperatures = -S+T; and increased snow and elevated temperatures = +S+T). -The data are currently from 19940616 to 200008101. ---DATA COLLECTION and PROCESSING: -Plant material is collected and oven-dried at 60C to a constant weight and subsequently ground to a fine powder. Carbon and nitrogen concentrations of subsamples of the ground plant material is determined by coupled combustion/reduction and gas chromatography (CHN-1000, LECO Corporation, St. Joseph, Michigan). ---DATA FORMAT: -Data are space-delimited ASCII and headings are SITE (dry heath tundra or moist tussock tundra), DATE (of collection), TREATMENT (-S-T, +S-T, -S+T, +S+T), SPECIES, %C, %N, C:N ratio. -Missing data indicated with -99.99. -DATA VERSION = 1.0 (13 March 2002), PRELIMINARY. ---DATA REMARKS: -Data should be considered preliminary and are subject to change in future versions of the data as further analyses are carried out.