Effect of krummholz establishment on soil previously occupied by tundra: carbon and nitrogen properties.

• Format: Dataset
• Language: unknown
• Published: Niwot Ridge LTER/University of Colorado1560 30th Street, CB [e-mail] 2001
• Subjects: NWT; Niwot Ridge LTER Site; LTER; Colorado; C; N; bulk density; carbon; d13C; d15N; krummholz; natural isotopic abu; nitrogen; soil; soil bulk density; soil carbon; soil carbon and nitr; tundra; Tundra
• Online Access: http://hdl.handle.net/10255/dryad.9473; http://metacat.lternet.edu/knb/metacat/knb-lter-nwt.132.2/xml

Previous work has shown that passage of Englemann spruce (Picea Englemanii) and subalpine fir (Abies lasiocarpa) tree islands across tundra lowers the soil carbon and nitrogen storage capacity of the top 15cm of soil (A horizon) (Pauker and Seastedt 1996). This data forms part of a study which seeks to further examine how changes in carbon storage capacity are associated with changes in soil physical properties. Soils were collected in 1994. We sought to determine whether there were changes in natural abundance of C and N isotopes associated with previously reported changes in C and N content. Any such changes in natural abundance of C and N isotopes may indicate differences in inputs to the ecosystem or differences in ecosystem processes that may account for the differences in N and C content that have been observed. In addition to measuring ratios of natural isotopes of C and N, we also measured C and N contents to provide a comparison with previous studies. In order to convert % N and C values to Kgs of N and C per m2 we used bulk density values, meaned across sampling dates, that had been previously measured for these sites (these raw data are available at: http://culter.colorado.edu/exec/.extracttoolA?krmslblk.ts). When N and C soil contents were considered on a percentage basis, levels at windward sites were significantly lower than those of undisturbed tundra, but levels directly beneath krummholsz were not significantly different from tundra soils. Bulk density was significantly lower under krummholz than other sites. Thus when N and C amounts were expressed on a volume (Kg m2, to a depth of 15cm) , they were significantly lower in both krummholz and windward sites than in undisturbed tundra. D13C values of soils under krummholz were significantly less negative under krummholz than from windward or undisturbed tundra sites. A less negative d13C value is indicative of less discrimination and may be attributable to either vegetation differences or differences in decomposition rates. D13C signatures of krummholz and tundra vegetation were also examined and are available at: http://culter.colorado.edu/exec/.extracttoolA?krmslrts.ts