Comparative analysis of growth-climate relationships, growth performance, and microenvironments of white spruce (Picea glauca) within three habitats in Spruce Woods Provincial Park, Manitoba
Growth - climate relationships, growth performance, and microenvironments of a disjunct population of white spruce [Picea glauca (Moench) Voss] were examined within three contrasting habitats (i.e., white spruce tree islands, open prairie, and aspen groves) at its southern limit of distribution in the prairie-forest boundary. The study was conducted within four mixed-grass prairie preserves in the Spruce Woods Provincial Park (SWPP) of southwestern Manitoba. Light and temperature conditions within the open prairie and island periphery accentuated the effects of the dry regional climate of the aspen parkland and mixed-grass prairie region. In contrast, light and temperature conditions under tree canopy of islands and aspen groves moderated the effect of the dry regional climate. The light-limited environments of the aspen groves and spruce islands outweighed the effect of moderated microclimatic conditions as low light conditions limited diameter growth and height growth of white spruce seedlings and saplings. Moisture deficiency exacerbated by temperature induced drought stress were factors that limited the growth of white spruce trees from spruce islands. The response of white spruce trees to the regional climate was moderated by the microclimatic conditions of the aspen groves since growth was restricted mainly by temperature induced drought stress.