IntensIve sIlvIculture - Forest Science Labs - Research Network ...

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Abstract: In six Douglas-fir [Pseudotsuga menziesii (Mirb.) Franco] stands in the Puget
Sound Region in Western Washington/USA, forest floor C and N pools were quantified on
control plots and on plots that had been fertilized repeatedly with urea 8-30 years ago (total
amount of applied N 0.9-1.1 Mg ha-1). Additionally, net N mineralization and nitrification rates
were assessed in field and laboratory incubation experiments. Forest floor C/N ratios were
decreased on the fertilized plots of all sites compared to the respective control plots. The
decreases were particularly strong at sites with initial C/N ratios larger than 30. On sites with low
productivity (site index at age 50: 30. For the investigated sites, fertilization effects on net N mineralization
sustained for at least 11 years after the last fertilizer application. Nitrification correlated strongly
with the forest floor pH; significant formation of NO3- was observed only for O layers with a pH
(H2O) higher than 4.5.
484. Puettmann, K.J., D.W. Hann and D.E. Hibbs. 1993. Evaluation of the size-density relationships
for pure red alder and Douglas-fir stands. Forest-Science 39(1): 7-27.
Keywords: planting operations
growth
tree/stand health
Abstract: Using previously published data, size-density relations were developed for pure
red alder (Alnus rubra) and pure Douglas fir (Pseudotsuga menziesii) stands in Oregon,
Washington and British Columbia, using quadratic mean diameter of the stand as the tree-size
variable. The resulting self-thinning or maximum size-density line for red alder had a steeper
slope (-0.64) than that for Douglas fir (-0.52). The assumption of a common slope for all species
is, therefore, not supported by this study. For red alder, the shape of the size-density trajectory
and the height of the maximum size-density line were not influenced by initial density or stand
origin. Red alder and Douglas fir mortality started at a relative density of 44% and 58%,
respectively.
485. Puttonen, P. 1987. Abscisic acid concentration in Douglas-fir needles in relation to lifting date,
cold storage, and postplanting vigor of seedlings. Canadian-Journal-of-Forest-Research 17(5):
383-387.
Keywords: nursery operations
growth
tree/stand health
tree physiology
tree phenology
Abstract: Spring-lifted seedlings (2+0) were grown outside in pots at Corvallis, Oregon, in
1982. In late July pots were watered weekly to induce dormancy. From early Sep., plants received
either a natural photoperiod or an extended (16 h) photoperiod for 6 wk. In mid-Nov. 1982 or
mid-Jan. 1983, the plants were lifted and stored in a cold room (4 degrees C) for 25 days, bare
rooted in polyethylene bags in the dark, or in pots in the dark or with an 8 h photoperiod. After
storage, seedlings were planted in a cold frame or in pots in a growth room with 16-h photoperiod