Spatially explicit modelling of coupled water and carbon cycles in Canada's forests and wetlands as affected by disturbance, climate, and atmospheric composition.
Published: 2006
Language: eng
Number of pages: 187
ISBN-13: 9780494218648
Description: The carbon (C) and water cycles and the interactions between them in terrestrial ecosystems are influenced by changes in climate, atmospheric composition, and disturbance regimes. During the last century, these types of changes have all occurred to Canada's forests and wetlands. The responses of the C and water cycles to such changes were studied through model simulations.Statistical analysis showed that SWC in Canada's forests and wetlands changed spatially and temporally, with an overall increase between 1901 and 2000, but a decrease between 1971 and 2000. The variation in SWC during 1901-2100 was projected to induce an average increase of 4.2 Tg C yr-1 in net C sequestration. Such increase is relatively small compared to the projected increase of 51.2 Tg C yr-1 caused by the integrated effect of changes in climate, CO2 concentration, and N deposition. Climate change was the largest contributor to a total increase of 3.9 Gt C in soils between 1901 and 2000, followed by the changes in forest age, CO 2 fertilization, and N deposition. Most of the simulated climate-induced increase in soil C stocks (1.29 Gt C) was from the contribution of increasing SWC (1.12 Gt C). However, a warm and dry climate between 1981 and 2000 caused soils to release 0.27 Gt C to the atmosphere. An increase of 1 K in annual mean temperature enhanced heterotrophic respiration by about 62 Tg C yr -1. A period with wet and cool climate increased soil C accumulation, while a warm and dry period had the opposite effect.Model validations showed that a new scheme is an improvement over a commonly used method in quantifying the effect of soil water on stomatal opening for simulating surface fluxes. This new scheme quantifies the uptake of water by roots based on root fraction and the vertical profile of soil water instead of only root fraction. The inclusion of lateral surface and subsurface water flows was found to be critical for simulating soil water content (SWC), water table depth, and C sequestration. Separate parameterizations for forests and wetlands are required for regional C budget estimation.
Notes: Source: Dissertation Abstracts International, Volume: 68-01, Section: B, page: 0155.

Thesis (Ph.D.)--University of Toronto, 2006.

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