Canadian Forest Service Publications

Fertilization and thinning effects on a Douglas-fir ecosystem at Shawnigan Lake on Vancouver Island. Some observations on salal and bracken fern undergrowth. 1979. Stanek, W.; Beddows, D.; State, D. Fisheries and Environment Canada, Canadian Forest Service, Pacific Forest Research Centre, Victoria, BC. Information Report BC-R-1. 11 p.

Year: 1979

Available from: Pacific Forestry Centre

Catalog ID: 4080

Language: English

Series: Information Report (PFC - Victoria)

Abstract

A thinning and N-fertilization experiment was established in an even-aged Douglas-fir forest at Shawnigan Lake, Vancouver Island in 1971, with replication in 1972. This study was concerned with the treatment effects on above-ground biomass, ground cover percent, and N content of salal, Gaultheria shallon Pursh., and bracken fern, Pteridium aquilinum (L.) Kuhn.

Forest thinning and fertilization as applied to forest stands in order to increase their productivity, also affect herbaceous and shrubby undergrowth. Thinning caused more light to penetrate through tree canopies and thus increased the undergrowth biomass. In contrast, fertilization caused an increase in density of tree canopies, thus decreased undergrowth ground cover and biomass. Combination of fertilization and thinning treatments benefited the undergrowth, heaviest thinning and moderate fertilization being the most beneficial.

The amounts of nitrogen tied up by undergrowth of fertilized plots were relatively small and are not likely to be critical for tree growth except in under very nitrogen-deficient soil conditions and in very young stands.