PARENT SESSION
Contributed Oral Session 79: Forest Ecology: Communities, Species Richness, and Coarse Woody Debris
Wednesday, August 10, 8:00 AM - 11:30 AM, Meeting Room 518 A, Level 5, Palais des congrès de Montréal
Modelling the long-term dynamics of coarse woody debris under the uniform shelterwood silvicultural system in central Ontario.
Vanderwel, Mark*,1, Malcolm, Jay1, Smith, Sandy1, 1 University of Toronto, Toronto, Ontario, Canada
ABSTRACT- Although forest management practices have been widely found to have negative effects on coarse woody debris (CWD), the long-term dynamics of these resources under partial harvesting systems in Ontario are poorly understood. Simulation modelling is a powerful approach for investigating patterns and processes of CWD accumulation through inputs from live tree mortality, the progressive decomposition of dead wood, and the creation and/or removal of material by disturbance events. In the present study, we developed models of eastern white and red pine (Pinus strobus and P. resinosa) CWD transitions through a series of snag and downed woody debris decay classes over time. Using these decomposition models, a stand growth simulator, and data on the immediate impacts of harvesting and fire on CWD, we then projected the quality and quantity of CWD under three scenarios: 1) for undisturbed pine stands; 2) for stands experiencing periodic surface fires; and 3) for stands managed under the uniform shelterwood silvicultural system. Snag densities were dramatically reduced under shelterwood management relative to the undisturbed and surface fire scenarios. Regular inputs from harvest residues tended to maintain an adequate total volume of downed woody debris under shelterwood management, but, unlike the non-harvest scenarios, this material was concentrated in a narrow range of decay classes at any given time. These simulation modelling results suggest that additional management guidelines may be needed if adequate levels of specific CWD resources are to be continuously maintained in Ontario's shelterwood-managed pine forests.
Key words: coarse woody debris, forest management, shelterwood, simulation modelling