Fertilization has continued to influence tree growth on both CH and HA sites. Total tree heights, volume stocking and average annual growth increment for the 1997 - 2002 period have been increased by fertilization. Scarification has increased tree size on CH sites but does not show continued influence on annual growth increments. Density-dependent competition has not greatly influenced tree growth but recent growth increments indicate that density stress is increasing as a growth-influencing factor particularly on CH sites. Mortality of hemlock was greater than that of cedar and was increased by fertilization on HA sites. Due to misclassification of some plots plus the presence of S6 and S7 pockets in some plots these growth results may be regarded as underestimations of growth potential on CH and HA sites. Fertilization has increased foliar P concentrations but not foliar N concentrations. Tree height growth increment was consistently well correlated with foliar P concentration across both sites for both species. Growth on HA sites was well correlated with foliar N concentration. Concentrations of other nutrients have been increased by fertilization, possibly due to an increase in their short-term availability due to extraction from the soil by the urea element in the fertilizer product. Foliar nutrient concentrations are within published ranges. An additional fertilizer application is suggested for this site, in order to prevent possibly impending growth check of hemlock on the CH portion of the trial and a general reduction in growth associated with crown closure and the increasing influence of density stress. A possible cleaning of natural regeneration ingress should also be considered. Possible forest health issues with this trial may include laminated root rot (Phellinus weirii (Murr.) Gilb.) centres and the incidence of (Didymascella thujina (Dur.) Maire) in cedar stands, particularly those that have been fertilized.
Roderick W. Negrave
Negrave, Roderick W.. 2004. Effects of establishment density, fertilization and scarification on growth and foliar nutrient concentrations of juvenile Western Red Cedar and Western Hemlock plantations on CH and HA sites: final report. Forest Investment Account (FIA) - Land Base Investment Program - Innovative. Forest Investment Account Report