FOREST CANOPIES AND THEIR INFLUENCE ON UNDERSTORY VEGETATION IN EARLY-SERAL STANDS ON WEST VANCOUVER-ISLAND

The abundance of shrubs, salal and salmonberry in particular, is a cha racteristic feature of the understory in old-growth, west coast forest stands. We analyzed relationships between forest canopy cover and the cover of the shrub layer, salal, salmonberry, herb layer, and moss la yer using data from 157 early-seral (35 year-old) stands from west Van couver Island having variable canopy cover, canopy species, and site q uality. The analysis indicated that (i) canopy cover was influenced by canopy species and site quality, (ii) canopy cover had a strong influ ence on the cover of shrubs but no influence on the cover of herb and moss layers, and (iii) site quality had a moderately strong influence on the cover of salal and salmonberry and a weak influence on the cove r of shrub, herb, and moss layers. As the canopy cover decreased from 95 to 5%, the shrub cover consistently increased from about 5 to 95%. The canopy cover alone was a good predictor of the cover of shrubs (R( 2) = 0.83), salal (R(2) = 0.72), and salmonberry (R(2) = 0.73), provid ing the stands were stratified into poor and rich soil nutrient strata . The quantified relationships between canopy cover and the cover of s hrubs, salal, and salmonberry provide a simple tool for foresters to m anipulate canopy cover of early-seral stands in perhumid cool mesother mal climates for creating suitable wildlife habitats.