Understorey environment and vegetation response after partial cutting and site preparation in Pinus strobus L. stands

Understorey vegetation response to thinning, site preparation and underplanting was investigated in three natural, 110-year-old eastern white pine (Pinus sti-obits L.) stands. The study was arranged in a split plot, randomized block design with four replicates, and included three thinning and four site preparation treatments. Early competition response, natural and planted white pine seedling growth and nutrient uptake were monitored. Light (PAR), soil moisture and temperature were assessed during the first two growing seasons. Environmental conditions varied with treatment. With increased thinning, overall the diversity of tree species decreased and shrub species increased, although this will change with time. PAR was the most crucial for successful seedling growth. At 50% PAR, seedling biomass of both natural and planted seedlings no longer appeared limited directly by light, and site preparation and brush control treatments resulted in further increased growth and improved seedling nutrition. (C) 2001 Elsevier Science B.V. All rights reserved.