HR: 11:35h
AN: B42B-05    [Abstracts]
TI: Nitrogen dynamics of a boreal black spruce wildfire chronosequence
AU: * Bond-Lamberty, B
EM: bpbond@wisc.edu
AF: University of Wisconsin-Madison, Dept. of Forest Ecology and Management 1630 Linden Drive #120, Madison, WI 53706 United States
AU: Gower, S T
EM: stgower@wisc.edu
AF: University of Wisconsin-Madison, Dept. of Forest Ecology and Management 1630 Linden Drive #120, Madison, WI 53706 United States
AU: Wang, C
EM: wangck-cf@nefu.edu.cn
AF: Northeast Forestry University, Ecology Program Northeast Forestry University, Harbin, WI 150040 China
AU: Cyr, P
EM: CyrP@agr.gc.ca
AF: University of Manitoba, Department of Soil Science 362 Ellis Building, Winnipeg, MB R3T 2N2 Canada
AU: Veldhuis, H
EM: veldhuish@agr.gc.CA
AF: University of Manitoba, Department of Soil Science 362 Ellis Building, Winnipeg, MB R3T 2N2 Canada
AB: This study examined the nitrogen (N) dynamics of a black spruce ( Picea mariana (Mill.) BSP)-dominated chronosequence in Manitoba, Canada. The seven sites studied each contained separate well- and poorly-drained stands, and all originated from stand-killing wildfires. Our goals were to (i) measure total N concentration of all biomass components and major soil horizons and (ii) compare N content and select vegetation N cycle processes among the stands. Vegetation N concentration varied significantly by tissue type, species, soil drainage, and stand age; woody debris N concentration increased with decay state and decreased with debris size. Soil N concentration declined with horizon depth but did not vary with stand age. Total (live + dead) biomass N content ranged from 3.5 to 30.9 g N m^-2 in the well-drained stands and 2.6 to 16.1 g N m^-2 in the poorly-drained stands. Mean soil N content (380.6 g N m^-2) was unaffected by stand age. Annual vegetation N requirement (5.9 and 8.4 g N m^-2 yr^-1 in the middle-aged well- and poorly-drained stands, respectively) was dominated by trees and fine roots in the well-drained stands, and bryophytes in the poorly-drained stands. Nitrogen retranslocation was significantly higher in deciduous than evergreen tree species, and in older than younger stands. Nitrogen use efficiency (NUE) was significantly lower in bryophytes than in trees. Tree NUE was lower in younger stands, but total stand NUE was similar (70-80 g g^-1 N) in all stands.
DE: 0469 Nitrogen cycling
DE: 0470 Nutrients and nutrient cycling (4845, 4850)
DE: 0486 Soils/pedology (1865)
DE: 0793 Biogeochemistry (0412, 0414, 1615, 4805, 4912)
SC: Biogeosciences [B]
MN: Fall Meeting 2005