Interactive effects of CO2, soil temperature, moisture and nutrients on black spruce ecophysiology

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The atmospheric carbon dioxide concentration ([CO2]) has been increasing rapidly since the Industrial Revolution and the increase will continue in the foreseeable future. The rising [CO2] will affect the physiology, growth and distribution of plants and ecosystems. Recent studies suggest that the climate change associated with increasing atmospheric [CO2] will be the most prominent in the boreal region. The boreal forest is the largest terrestrial ecosystem on the earth. Its ecophysiological activities can have a profound impact on the environmental conditions of the earth's surface. For example, its photosynthesis is a significant force in the fixation of atmospheric CO2 and the production of oxygen. The ecophysiological regulation of water flux from the boreal forest to the atmosphere has a major influence on the properties of the lower atmosphere. The ecophysiological processes are in turn controlled by climate conditions. Black spruce is the most abundant tree species in the boreal forest and its response to the rising [CO2] will exert a major influence to the overall response of the boreal forest to global climate change. Black spruce grows over a wide range of soil temperature, moisture and nutrient conditions. The soil conditions will likely influence the ecophysiological responses of the species to rising [CO2]. However, our understanding of these effects is very limited. This research will conduct a series of controlled experiments to examine how soil temperature, moisture and nutrition interact with each other in influencing the ecophysiological activities of black spruce under current and future atmospheric CO2 concentration. Computer models will be developed describing the responses. These models will provide a critical linkage between tree physiology models and soil models within ecosystem models for studying the response of boreal forests to the global climate change.