Effects of variable nitrogen fertilization on growth, gas exchange, and biomass partitioning in black spruce and tamarack seedlings.

• Author(s) / Creator(s)

  • Macdonald, S. Ellen
  • Islam, M. Anisul

• In order to compare the ability of black spruce (Picea mariana (Mill.) BSP) 1 and tamarack (Larix laricina (Du Roi) K. Koch) to adjust to variable edaphic conditions, 2 as found in natural peatlands, we varied nitrogen (N) fertilization of seedlings in a growth 3 chamber experiment over two growing seasons and examined growth, biomass 4 partitioning, and gas exchange. Seedlings from both species received either high-N (100 5 μg L-1) or low-N (10 μg L-1) in consecutive growing seasons as follows: a) low-N + low-6 N (LL); b) low-N + high-N (LH); c) high-N + low-N (HL); and d) high-N + high-N 7 (HH). Both species had greater shoot and total dry weight after one year in the high-N 8 treatment, as compared to seedlings grown for one year under low-N. For tamarack these 9 differences were larger and they also exhibited a positive effect of fertilization on net 10 assimilation and water-use efficiency. Only black spruce exhibited a positive growth 11 response following the move to higher nitrogen fertilization in the second year (LL vs. 12 LH), whereas only tamarack exhibited a negative growth response following the move to 13 lower nitrogen fertilization (HH vs. HL). Still, tamarack had greater total biomass at the 14 end of two years than did black spruce, irrespective of fertilizer treatment. Both species 15 had greater total biomass in the HL treatment than in the LH treatment. Tamarack seems 16 able to take advantage of favorable nutrient conditions, but it also experiences more 17 dramatic growth declines under poor or deteriorating conditions. While black spruce 18 grows more slowly than tamarack it is somewhat buffered from declines in growth under 19 poor or deteriorating conditions. Each species appears to be adapted in its own way to the 20 edaphic heterogeneity that exists in natural boreal peatlands.

• Date created

  2005

• Subjects / Keywords

  • Gas exchange
  • Black spruce
  • Biomass accumulation
  • Nitrogen fertilization
  • Plasticity
  • Tamarack

• Type of Item

  Article (Published)

• DOI

  https://doi.org/10.7939/R3QZ22K1Q

• License

  © 2005 Canadian Journal of Botany. This version of this article is open access and can be downloaded and shared. The original author(s) and source must be cited.