Figure 2.

Observations of whole-plant starch (A) and sugar (B) during shading in Douglas-fir (Pseugostuga menziesii) seedlings. Seedlings received zero light for the duration of the experiment and were maintained at three different temperatures (30°C, 20°C, and 10°C), with lower temperatures resulting in longer survival times. All seedlings were dead at the end of the experiment (J.D. Marshall, personal communication). Control plants received full sunlight, and both starch and sugar contents stayed above the values observed for shaded plants. Whole-plant (shoot, coarse root, new and old fine roots) carbohydrates were calculated from table 3 and figures 2 to 4 in Marshall and Waring (1985).