Morphological Grading of White Spruce Nursery Stock

Abstract

An experiment was begun in 1974 to examine morphological criteria of 3 + 0 and 2 + 2 white spruce planting stock in relation to subsequent performance. Trees (250) of each age-class were obtained from Midhurst Nursery and measured (top length, stem diameter and top-root ratio by volume of water displacement) and then planted on a cultivated site at Midhurst Research Unit. Survival and growth was measured for 6 years after planting.The 3 + 0 seedling stock was found to be inferior in survival, growth and cost for a stated objective aggregate height of stand. Top length, stem diameter and root volume were all good indicators of subsequent height growth. Tentative recommendations for 2 + 2 white spruce are: a minimum 22 cm top length, minimum 4 mm stem diameter, minimum 5 ml root volume, and top-root ratio range of 1.0 to 3.5:1.