LEVELS-OF-GROWING-STOCK COOPERATIVE STUDY IN DOUGLAS-FIR - REPORT NO-12 - THE IRON CREEK STUDY - 1966-89

Results of the Iron Creek installation of the levels-of-growing-stock study in Douglas-fir (Pseudotsuga menziesii (Mirb.) Franco) are summar ized. To age 42 (planned completion of the experiment) volume growth i n this site II Douglas-fir plantation has been strongly related to lev el of growing stock, partially offsetting the decrease in volume growt h percent expected with increasing growing stock. Basal area growth-gr owing stock relations were much weaker than those for volume. Marked d ifferences in tree size distributions have resulted from thinning. Per iodic annual volume increments are two to three times greater than mea n annual increments at age 42; this stand is far from culmination. Res ults in general are similar to those reported for other installations in the series on medium to good sites.