© 2005 Heron Publishing—Victoria, Canada
Effects of soil temperature on shoot and root growth and nutrient uptake of 5-year-old Norway spruce seedlings
M. Lahti (1, 2), P. J. Aphalo (3), L. Finér (4), A. Ryyppö (4), T. Lehto (4) and H. Mannerkoski (4)
1. Finnish Forest Research Institute, Suonenjoki Research Station, Juntintie 154, FIN-77600 Suonenjoki, Finland / 2. Corresponding author (markku.lahti@metla.fi) / 3. Department of Biological and Environmental Science, FIN-40014 University of Jyväskylä, Finland / 4. University of Joensuu, Faculty of Forestry, P.O. Box 111, FIN-80101 Joensuu, Finland / Received January 28, 2004; accepted June 4, 2004; published online November 1, 2004
Summary
Soil temperature is a main factor limiting root growth in the boreal forest. To simulate the possible soil-warming effect
of future climate change, 5-year-old Norway spruce (Picea abies (L.) Karst.) seedlings were subjected to three simulated growing seasons in controlled environment rooms. The seedlings were
acclimated to a soil temperature of 16 °C during the first (GS I) and third growing seasons (GS III), but were assigned to
random soil-temperature treatments of 9, 13, 18 and 21 °C during the second growing season (GS II). In GS II, shoot diameter
growth was lowest in the 21 °C treatment and root growth was lowest in the 9 °C treatment. In GS III, shoot height and root
length growth improved in seedlings that had been kept at 9 °C during GS II, indicating compensatory growth in response to
increased soil temperature. The temporary decrease in soil temperature had no long-lasting significant effect on seedling
biomass or total nutrient uptake. At the end of GS III, fine roots of seedlings exposed to a soil temperature of 21 °C in
GS II were distributed more evenly between the organic and mineral soil layers than roots of seedlings in the other treatments.
During GS II and GS III, root growth started earlier than shoot growth, decreased during the rapid shoot elongation phase
and increased again as shoot growth decreased.
Keywords:
allocation, biomass, fine roots, increment, nutrients.
