Plasticity in above-ground biomass allocation in Fagus sylvatica L. saplings in response to light availability

The paper presents the production and allocation of aboveground biomass in 7-yr-old saplings of European beech (Fagus sylvatica L.) growing along an environmental gradient with a total light transmittance (Tot) ranging from 6% to 80%. Non-overtopped individuals, not suppressed by surrounding saplings were sampled at the end of growing season. The total aboveground biomass production on the gradient varied within 1.7-261.0. Light in the log-log linear relationship accounted for 83% of this variability. The plants growing in the shade had lower mass of aboveground compartments, lower total leaf area, higher fraction of biomass allocated in foliar mass and lower in the in the woody mass compared to the plants growing in the high-light environment. The major changes in effects of light availability on biomass allocation occurred up to about 20% of Tot. Decreasing accessible light was responsible for a non-linear increase in interceptive leaf area per unit of biomass and decrease in amount of biomass allocated per a unit of branch and stem length - necessary for leaf display. There was a close correlation between mass of aboveground plant compartments, documented by Pearsons r values of 0.98-0.99. Accompanied with different plant size, observed differences in biomass partitioning in response to light could be viewed as plastic adjustment to environmental heterogeneity in even-aged European beech saplings.