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

72
2 wk later than unpruned seedlings. Shippable yield of seedlings pruned tall and early and of
unpruned seedlings were n.s.d, although more pruned seedlings had multiple leaders. Pruned
seedlings were smaller than unpruned seedlings at the time of planting. Survival and growth were
the same for pruned and unpruned seedlings in the 1st year after planting. Pruned seedlings grew
more than unpruned seedlings in the 2nd year, but were still shorter after 2 yr. Field growth was
greater in seedlings pruned tall or early than in seedlings pruned short or late. It is concluded that
pruning should be continued as a cultural practice if it benefits nurseries, but that late short
pruning should be avoided.
160. Edgren, J.W. 1981. Field performance of undercut coastal and Rocky Mountain Douglar-fir 2+0
seedlings. Tree-Planters' Notes 32(3): 33-36.
Keywords: nursery operations
tree/stand health
growth
Abstract: Seedlings from 1 seed source each of Pseudotsuga menziesii var. menziesii
(coastal) and P. menziesii var. glauca (Rocky Mountain) were grown in a nursery in Washington
and half were undercut at 15 cm below the surface at 1-yr-old. Seedlings were lifted in March the
next yr (1968) and planted out at 2 sites in Oregon. Survival of undercut coastal firs 3 yr after
planting was significantly better than controls. Survival of Rocky Mountain fir was not
significantly affected by undercutting. Ht. growth of control seedlings of both varieties was
significantly greater in their 1st season than that of undercut seedlings, but the differences
disappeared the following year.
161. Edmonds, R.L. and T. Hsiang. 1987. Forest floor and soil influence on response of Douglas-fir to
urea. Soil-Science-Society-of-America-Journal 51(5): 1332-1337.
Keywords: fertilization
thinning
growth
soil properties
Abstract: Data from the Regional Forest Nutrition Research Project (RFNRP) in
Washington and Oregon were analyzed to improve stand-specific prediction of Douglas-fir
[Pseudotsuga menziesii (Mirb.) Franco] response to urea fertilization. The response variable
(relative difference in volume growth between fertilized and control plots 4 yr after fertilization
with 448 kg N/ha) was regressed against 28 stand and site variables (e.g., age, elevation, forest
floor C/N ratio, soil cation exchange capacity, etc.) using stepwise multiple regression analysis.
Data from 120 installations were stratified by thinning level (thinned or unthinned), geographic
location (provinces), and site quality (site index and class). Forest floor C/N ratio was the
dominant variable related to response. In thinned installations of high site quality (site classes 1
and 2), 60% of variation in response was explained by the forest floor C/N, and 75% of the
variation in response was explained with inclusion of surface soil exchangeable K. In thinned,
low site quality stands, response was not as well related to forest floor C/N. Analysis of the data
by province indicated that S may be limiting in southwest Oregon and P in coastal Washington.
162. Edwards, D.G.W. and Y.A. El-Kassaby. 1988. Effect of flowering phenology, date of cone
collection, cone-storage treatment and seed pretreatment on yield and germination of seeds from a
Douglas-fir seed orchard. Forest-Ecology-and-Management 25(1): 17-29.