Foliar analysis and response of fertilized chlorotic Sitka spruce plantations on salal-dominated cedar–hemlock cutovers on Vancouver Island

Abstract

A series of microplot and conventional plot trials were used to determine the nutritional status and required nutrient additions to bring young chlorotic Sitka spruce (Piceasitchensis (Bong.) Carr) plantations out of "check." Check occurs on clear-cut and burned old-growth western red cedar (Thujaplicata Donn ex D. Don) and western hemlock (Tsugaheterophylla (Raf.) Sarg.) stands in the Coastal Western Hemlock biogeoclimatic zone growing on deep morhumus Podzols invaded by dense salal (Gaultheriashallon). Microplot trials identified the requirement for N and P. Checked trees responded to fertilization immediately with a 4- to 8-year temporary increase in leader length. Grubbing out of aboveground salal did not improve tree nutrition. There is a close parallel to "heather check" noted with Sitka spruce in British and Irish moorlands; a possible allelopathic effect of salal is suspected. It is concluded that one or more N and P additions are required to establish crown closure. Fertilized Sitka spruce show a high incidence of spruce weevil attack. The deficient and optimum foliar nutrient concentrations developed in Britain for the diagnosis of Sitka spruce appear to be applicable.