How does overstory retention affect above- and below-ground resource availability and seedling performance?: implications for silvicultural systems choice in the ESSF

In subalpine forests, low light, low soil temperature, and low nitrogen (N) availability may co-limit tree growth. We used greenhouse and field experiments to quantify the effects of these factors on the growth of Picea engelmannii and Abies lasiocarpa seedlings from the subalpine forests of British Columbia. For approximately 500 nitrogen fertilized and unfertilized eight-year old planted seedlings from shelterwood, patch cut, and clear-cut stand treatments, growth was examined as a function of soil temperature, light, and stand treatment. In a greenhouse, growth and photosynthesis were examined at root temperatures representing the range of field growing season temperatures (5, 10, and l5~C). Fertilizer effects on diameter growth in the field were not significant indicating that the seedlings were not N limited. In multiple regression, temperature and light (both partial p