Duration: 2001-2003 Keywords: allocation, carbon, conifers, decomposition, nitrogen, root growth, soil temperature
Several experiments have been carried out in the root lab of the Joensuu Research Centre during the project.
Experiment 1: The effects of soil temperature on phenology, morphology and biomass allocation in Scots pine (Pinus sylvestris L.) seedlings.
When the soil temperature was between 5oC and 17oC there were no effects on the initiation of shoot or root growth elongation. Instead, low soil temperature decreased total shoot and root elongation. The biomass of the seedlings was the lowest in the lowest soil temperature and the highest in 13oC. Root biomass increased with increasing soil temperature. Concomitantly biomass allocation to roots increased to some extent. Soil temperature had no effects on the sugar content of roots. Instead, the sugar content of the current year needles increased with increasing soil temperature.
Experiment 2: The effects of soil temperature on gas exchange and nitrogen and chlorophyll content of needles of 5-years old seedlings of Norway spruce (Picea abies (L.) Karst).
Soil temperatures in different treatments were 9oC, 13oC, 18oC, and 21oC during the growing season. Low soil temperature decreased net assimilation rate of needles and slightly impaired stomatal conductance and transpiration rate. Total chlorophyll content of needles differed significantly between treatments. Instead, the chlorophyll a/b-ratio was approximately the same. Low soil temperature affected the starch content of needles that was the highest in the lowest temperature.
Experiment 3: The effects of timing of soil frost thawing on the growth and physiology of 5-years old Scots pine (Pinus sylvestris L.) seedlings.
According to the preliminary results the timing of soil frost thawing significantly affects Scots pine seedlings. Serious, irreversible damage were observed in the seedlings when the soil frost thawing was delayed 2 weeks in respect to increase of air temperature, photon flux density and photoperiod. The effects were found in several physiological attributes. Timing of soil frost thawing had a clear impact on the initiation of growth. The earlier the soil frost thawing appeared as the earlier initiation of shoot elongation, irrespective of similar air conditions.
Project leader:
Repo, Tapani
The Finnish Forest Research Institute,
Joensuu Office,
PL 68, FI-80101 JOENSUU, FINLAND
Phone: +358 29 532 3136
E-mail: tapani.repo@metla.fi
Other researchers: Finér, Leena, JO (2001), Sutinen, Sirkka, JO (2002-03)
Updated 12.06.2012
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