Survival and growth of Douglas-fir seed sources in the Hospital Tract rangewide source archive plantation Public Deposited
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"In 1954, Dr. Helge Irgens-Moller initiated a rangewide collection of seed and seedlings of Douglas-fir (Pseudotsuga menziesii (Mirb.) Franco). Nearly 700 trees or stands were sampled in 10 western states, Canada, and Mexico. From 1957 to 1971, 639 of these collections were planted in the Hospital Tract Rangewide Source Archive near Corvallis, Oregon. By 1989, the trees were from 20 to 34 years old; it became apparent that thinning the archive would be necessary in order to preserve the slower growing sources. This prompted growth and survival measurements and a complete inventory of the archive. Overall survival for all years of planting was greater than 80 percent for coastal sources (var. menziesii), but less than 60 percent for interior sources (var. glauca). The average diameter at breast height (DBH) of surviving trees was 29.05 cm; the range was from 1.2 to 61 cm. An analysis of the 1957 and 1961 plantings revealed that local and other low elevation coastal sources had the fastest growth and highest survival in the archive. High elevation sources from the Cascade Range had significantly smaller DBH, but higher survival. Southern interior sources from Arizona and New Mexico had the smallest DBH and lowest survival; northern interior sources from Montana and Idaho were intermediate in survival and DBH. Geographical variation among sources in the Hospital Tract was associated with environmental gradients, supporting the previously held conclusion that much of the genetic variation on a geographical scale in Douglas-fir is the result of adaptation."--Summary.
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