Effects of intensive harvesting on forest floor properties in Betula papyrifera stands in Newfoundland

Abstract

Abstract. Betula papyrifera (White birch) is a common tree throughout the boreal forest of Canada; makes up 12% of the total tree volume in insular Newfoundland. It forms pure stands after harvesting and wildfire disturbance and it is a common component in most softwood stands. Little is known regarding the environmental impact of whole‐tree or conventional harvesting of this species and variation in impact related to variation in soil and site conditions.This study investigates litter and organic matter production and related site ecology in nine medium to high quality Betula papyrifera stands in three locations in central Newfoundland on a variety of land form and drainage conditions. Three sites, Badger West (BW), Moose Pond (MP) and Middleton Lake (ML) were selected. The ML site has the highest quality (with the best height/age ratio, 18 m/60 yr, and height/DBH ratio, 18 m/30 cm, followed by MP and BW. Litter depth on well developed moders or mulls was usually 2 ‐ 3 cm and varied from 1 ‐ 15 cm. Forest floor depths (measured in 324 profiles) rarely reached 20 cm and was commonly 5 ‐ 10 cm; it varied with position and site. Total and available nutrients indicate that B. papyrifera produces one of the highest ‐quality organic matter types of the local forest types and is important in improving site quality. The mean N‐concentration in green foliage (2.21%) and trapped litter (1.03%) was highest at the best quality site ML, followed by MP and BW. The concentration of calcium, 0.85%, was highest at the poorest quality site. Four years after harvesting, litter depth significantly decreased in all sites and treatments with the exception of the BW whole‐tree harvest treatment. Total forest floor depth significantly decreased at all sites in the stem‐only harvest treatment as well as the MP whole‐tree harvest treatment.There was a significant decrease in available nitrogen following harvesting in both treatments at both the MP and BW sites. Change in available phosphorus was insignificant, with the exception of an increase in the MP stem‐only harvest treatment. There was a significant decrease in available potassium at both the ML and BW whole‐tree harvest treatments, but a significant increase in the stem‐only harvest treatments at ML and MP. There was a significant decrease in available calcium in both treatments at both the MP and BW sites.