---TITLE: Eurasian Plant Nutrient Survey

---AUTHORS:
-Jeffrey M. Welker, Ingibjörg S. Jónsdóttir, Jace T. Fahnestock
-JMW and JTF at Natural Resource Ecology Laboratory, Colorado State University, 
Fort Collins, CO 80523-1499.  Phone: 970-491-1796; Fax: 970-491-1965; Email: 
jwelker@nrel.colostate.edu; jace@nrel.colostate.edu
-ISJ at 2The University Courses on Svalbard, P.O. Box 156, N-9171 Longyearbyen, 
Norway.  Email: isj@unis.no

---DATA SET OVERVIEW:
-Ecophysiological characteristics of clonal Carex arctic plant species from the 
Eurasian Arctic.  Data are leaf d13C, %N, and d15N of Carex ensifolia Krecz. 
ssp. arctisibirica Yurtsev, Carex lugens Holm, and Carex stans Drej from a 
series of tundra sites visited in summer 1994 as part of the Swedish-Russian 
Tundra Ecology -1994 expedition aboard the Russian ice breaker R/V Akademik 
Fedorov.  Additional information about the expedition and location of sites are 
found in Ambio 28: No. 3 (May 1999).

---DATA COLLECTION and PROCESSING:
-At each site, samples of one or two dominating Carex taxa were collected from 
mesic tundra for later analysis in the laboratory.  Along 80-120 m transects at 
each site, ten randomly chosen clonal fragments were carefully removed from the 
soil and preserved in a plant press.  Clonal fragments consisted of 
interconnected ramets, including vegetative juvenile (<2 years old) and mature 
vegetative ramets along with reproductive ramets (as indicated by the presence 
of an inflorescence).  The material was allowed to air dry and stored under 
cool temperatures.
-In the fall of 1999, a portion of each replicate clonal fragment from 13 of 
the 17 sites were examined and interconnected juvenile, mature and reproductive 
ramets were severed (material was not available from all ten replicates or from 
the remaining four sites).  Green leaf material was separated from dead leaves 
and oven dried at 60oC for 48 hrs, ground to a fine powder and analyzed for 
total C & N by combustion on a Carlo Erba CHN analyzer.  The combusted samples 
were then passed into an Isoprime Stable Isotope Mass Spectrometer under 
continuous flow and the 13C/12C ratio and the 15N/14N ratio of the CO2 and N2 
gas, respectively was measured.  The isotopic ratios were then converted to 
"delta units" (d) in parts per thousand (‰) following the formula:
d = (Rsample/Rstandard-1) 1000
where R is the molar ratio of heavy to light isotopes (13C/12C, 15N/14N).  The 
standard was PDB for carbon and atmospheric air for nitrogen.  Leaf carbon 
isotope discrimination (?, LCID) values were calculated from the leaf carbon 
isotope ratios with the 13C of the atmosphere assumed to be -8.0 ‰.

---DATA FORMAT:
-Column delimited ASCII
-Data columns are Site, Julian sample date (1994), Tiller type (DT=Daughter 
tiller, MT=Mature tiller, RT=Reproductive tiller), Replicate sample number, 
d13C (‰), %N, d15N (‰)
-Data version 1.0 (27 February 2002)

---REFERENCES:
-Ambio 28: No. 3 (May 1999)