Growth and acclimation of planted white pine and white spruce seedlings in response to environmental conditions

Abstract

A factorial experiment was used to examine the effects of soil temperature, brush competition, and fertility on the postplanting growth and development of white spruce (Picea glauca (Moench) Voss) and white pine (Pinus strobus L.) on a clear-cut forest site at the Petawawa National Forestry Institute. Environmental monitoring was used to confirm that soil temperature treatments were effective and that the brush competition treatments caused significant (.alpha. = 0.0001) differences in photosynthetically active radiation at tree level. On the basis of foliar analysis, both fertilization and brush control improved nutrient availability to the planted trees. Owing to adequate, well-distributed precipitation, soil moisture tension was not greater than 0.6 bars (1 bar = 100 kPa) in any treatment during the growing season. Growth response by both species was dominantly controlled by the soil temperature factor. Fertility produed secondary benefits to white pine, and brush control had secondary benefits to white spruce. Examination of a developmental sequence of height growth, leaf length growth, basal area growth, and terminal bud mass indicated that soil temperature treatments were beneficial throughout the growing season, that brush control was important only in late season, and that fertilization had slight negative effects in early season but a positive effect by late season. Developmental features also indicated that soil temperature effects were manifested by reduced shoot and needle extension in the trees, competition effects by reduced availability of light, nutrients, and moisture, and fertilizer effects by increased foliar element concentrations.