© 1999 Heron Publishing—Victoria, Canada
Biomass and nutrient allocation in Douglas-fir and amabilis fir seedlings: influence of growth rate and temperature
B. J. Hawkins (1), S. B. R. Kiiskila (2) and G. Henry (1)
1. Centre for Forest Biology, University of Victoria, P.O. Box 3020, Victoria, B.C. V8W 3N5, Canada / 2. Pacific Regeneration Technologies, Red Rock Nursery, R.R. 7, RMD 6, Prince George, B.C. V2N 2J5, Canada / Received September 23, 1997
Summary
Allocation of biomass and nutrients to current-year and one-year-old shoots and roots of two-year-old conifer seedlings with
differing rates of growth was studied. Differences in growth rate were achieved by selecting fast- and slow-growing populations
of the relatively fast- and slow-growing conifer species, Pseudotsuga menziesii (Mirb.) Franco and Abies amabilis Dougl. ex Loud, respectively. Environmentally controlled differences in growth rate were induced by placing half of the seedlings
in a 10 °C growth chamber and half in a 20 °C growth chamber in their second growing season. Seedling samples were harvested
in May, before the temperature treatment, and in July and November of the second growing season, and biomass and nutrient
concentrations of current-year and one-year-old shoots and roots were determined.
Seedling biomass and nutrient allocation differed among the high-growth treatments. Seedlings exhibiting high growth in response
to the 20 °C treatment and faster growing populations within species both showed increased allocation to new shoots, whereas
seedlings of the fast-growing species showed greater allocation to old shoots than to new shoots. Increased growth increased
nutrient uptake, but nutrient concentration decreased with growth rate as a result of dilution, so that faster-growing seedlings
had greater nutrient-use efficiency than slower-growing seedlings. Retranslocation of P and K was seen in the second year
only in slow-growing populations at 10 °C. Nutrient concentrations of one-year-old plant parts decreased in the second year,
indicating new growth was a stronger sink for nutrients than second-year growth.
Keywords:
Abies amabilis, nutrient uptake, nutrition, Pseudotsuga menziesii, retranslocation.
