Notes: Effects of Light Intensity and Temperature on the Growth of Douglas-Fir and Incense-Cedar Seedlings
Seedlings of Douglas-fir (Pseudotsuga menziesii [Mirb.] Franco) and incense-cedar (Calocedrus decurrens [Torr.] Florin) were grown together in six moist growth-chamber environments to compare growth in warm and cool temperatures, determine relative shade tolerances, and investigate the effects of temperature on shade tolerance. Incense-cedar grew larger than Douglas-fir in cool temperatures under all three light intensities used (5, 24, and 420 E.m-2.s-t), but Douglas-fir grew as large or larger than incense-cedar in warm temperatures under light intensities of 24 and 420 E. The relative allocation of growth to shoots and roots was allometric and similar for warm and cool temperatures under 24 and 420 E in the incense-cedar seedlings but not in the Douglas-fir seedlings. Incense-cedar seedlings were more shade tolerant than Douglas-fir seedlings. High temperatures reduced the shade tolerances of both species. For. Sci. 34(1):215-223.
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