Bareroot Sitka spruce <Picea sitchensisl were planted on the high bench floodplain of the Skeena River at Salvus in spring 1972, following blade-scarification in 1971/72. Scattered 18 year old 1-3 metre tall Sitka spruce of low vigour can be found throughout Salvus beneath the 10-12 metre canopy of red alder CAlnus rubral. With the intention of finding a successful silvicultural procedure for conversion of robust deciduous forest into a Sitka spruce and western redcedar < Thuja plicatal plantation, ten treatments including a control were selected. Pre-treatment vegetation sampling took place in August 1986. Treatments were applied in 1987, followed by post-treatment vegetation sampling in 1988, 1989 and 1990. In GIRDLE, removal of the red alder overstory released the understory, mainly red elderberry <Ssmbucus racemosal, salmonberry <Rubus spectabilisl and thimbleberry (Rubus parviflorus>. Existing plants increased rapidly in height and vigour, preventing re-establishment of red alder or, indeed, anything else. Apart from the lack of the alder canopy, vegetation composition and structure was very similar to CONTROL. In BURN and HSQ/SPRA Y, all of the existing vegetation was removed but the forest floor was not severely disturbed. Seed-banking species, especially red elderberry, quickly re-established as did a variety of other shrubs and herbs. Red alder cover has remained low, and structural and species diversity is highest on these plots. BL/GRASS controlled the vegetation height and greatly slowed recolonization by shrub species; however, the extremely dense grass cover could have negative impacts on planted conifer seedlings and certainly has short-term negative impacts on biodiversity. The other two bladed treatments <BLADE and SP/BLADE) have resulted in very dense regrowth of young alders from seed. This might be partially avoidable by scarifying in spring before the arrival of wind-borne alder seeds in late summer. As performed at Salvus, these treatments seem to be most useful for enhancing vole populations.
Allen Banner, Sandra Thomson, Alex Inselberg. 1993. Conversion of Multistoried Brush Fields to Coniferous Plantations Secondary Plant Succession: Results of Third Year Post-Treatment Sampling. FLNRORD
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