Effects of neutral shade and growing media on growth, biomass allocation, and competitive ability of Gaultheria shallon

Abstract

After two growing seasons salal produced, on average, five times as much total dry weight in 100% as in 5% full sunlight; no statistical differences were found between the relatively rich and poor growing media and between associated Sitka spruce Picea sitchensis and western red cedar Thuja plicata. The leaf to fineroot ratios of salal were 3.7 and 8.7 times greater under 5% compared with 100% full sunlight on the relatively rich and poor growing media, respectively. Proportionally more leaf and less fine-root and rhizome biomass of salal were produced at 5 and 10% compared with 30 and 100% full sunlight. Rhizome production was the component of salal the most affected by shading. Leaf area of salal increased and leaf thickness and specific leaf weight decreased with shading. Growth of both conifer species was improved slightly by a reduction in salal biomass. -from Author