Although the Douglas-fir region of the northwestern United States and British Columbia is frequently considered to have a common silviculture, obstacles to successful regeneration of the species range from competing vegetation and mammals on the mesic sites to extreme drought and heat on the xeric southerly exposures in northern California and southern Oregon. Recent reports on Douglas-fir, Pseudotsuga menziesii (Mirb.) Franco, by Ferrell and Woodard (1), Pharis and Ferrell (8), and Zavitkovski and Ferrell (11, 12) describe studies that demonstrated differences by seed source of response to drought stress of Douglas-fir seedlings under laboratory and greenhouse conditions. Our study was undertaken to determine whether planting stock raised from seed collected from mesic and xeric sites would demonstrate a differential survival under drought stress. And, further, to determine whether such survival differences were correlated with definite seedling parameters.
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