Conclusions
For Liriodendron the inclusion of the costs of night leaf respiration, leaf construction,
and associated stem and root tissue results in a staggering 7- to 110-fold increase
in the compensation point over that expected based on instantaneous leaf respiration
alone. The increase from 12 to 1438 pmol m-2 s- ' in compensation point due to such
factors is huge compared to the range of instantaneous leaf compensation points seen
among vascular plants, and suggests that certain of these factors-notably the construction
costs of leaves, stems, and roots-may have an overwhelming effect on a plant's
ecological compensation point. Of what significance is an instantaneous leaf compensation
point of 1 pmol m-2 s - ', or 0.001 pmol m-2 s- ', if tissue construction costs
raise the ecological compensation point by 100 pmol m-2 s- '?