Photosynthesis/respiration balance of a prairie ecosystem: North and South Saskatchewan River watersheds

The location of the hypothesized “missing carbon sink” has become a subject of open debate in the scientific community, with North America considered to be a prime location for such a sink. While forest ecosystems are considered to be the major candidate, Prairie ecosystems, with their large capacity to store carbon in their soils, may or may not be an ancillary candidate. The North and South Saskatchewan River watersheds are a prime example of such prairie ecosystems and, with this in mind, I attempted to quantify their role as potential sources or sinks of atmospheric CO₂. The sequestration of atmospheric CO₂ by plants via photosynthesis requires that water and CO₂ be utilized at a specific ratio called the water utilization efficiency (WUE). Thus, knowing the hydrological budget of a watershed, specifically the transpiration component, it is possible to calculate its net primary productivity (NPP). This, combined with biological model estimates for heterotrophic soil respiration (R_h), enables evaluation of source and sink tendencies in the watershed. (Abstract shortened by UMI.)...