© 1991 Heron Publishing—Victoria, Canada
Carbon dioxide enrichment accelerates the decline in nutrient status and relative growth rate of Populus tremuloides Michx. seedlings
K. R. Brown (1, 2)
1. Department of Forest Science, University of Alberta, Edmonton, Alberta, Canada T6G 2H1 / 2. Department of Forest Science, University of British Columbia, Vancouver, B.C., Canada V6T 1W5 / Received January 4, 1989
Summary
Changes in growth dynamics and mineral nutrient concentrations were measured in Populus tremuloides Michx., trembling aspen, grown for 100 days following germination in atmospheres containing 350 or 750 μl l–1 CO2. Seedlings were fertilized with nitrogen (N) at concentrations of 15.5 mM (high-N), 1.55 mM (medium-N), or 0.155 mM (low-N).
Initially, relative growth rates were enhanced by CO2 enrichment in each N regime, but the effects did not persist. In plants grown in high-N or medium-N, foliar concentrations
of Ca and Mg decreased in response to CO2 enrichment. During the 100-day study, whole-plant concentrations of N and P decreased in all treatments. The decreases in
mineral nutrient concentrations over time were accelerated in CO2-enriched plants and accompanied the disappearance of the CO2-induced growth enhancement. It is concluded that the depression of relative growth rates often associated with long-term
CO2 enrichment of plants may result from decreases in plant nutrient status.
