What is Forest Stand Dynamics?
Forest ecosystems are fundamentally a network of interacting elements, which in turn, affect tree recruitment, growth, and mortality. The interactions among individual trees and their spatially heterogeneous environment are inherently local in nature acting at a neighbourhood scale over restricted distances.
Forests exhibit elements of quasi-chaotic and uncertain behaviours as a result of interactions among many non-linear relationships. Development of forests include many components of randomness (e.g., seed dispersal, neighbourhood composition, windstorms), but forests do not develop randomly. Complex behaviour is best represented using a “bottom-up” approach to modeling. Each hierarchical element is modeled as a discrete agent or object state, where each entity has functions that are characterized by relationships described by rules (or equations) and constant values or variables.
What is SORTIE?
SORTIE is an individual-tree, spatially-explicit model of forest dynamics. It originated from the small-scale disturbance model SORTIE developed and tested in the early 1990s for transitional oak-northern hardwood forests in the northeastern US (Pacala et al. 1996). In 1995 Dave Coates, Phil LePage, Elaine Wright and other scientists from the Research Section of the British Columbia Forest Service in Smithers, BC began collaborating with Charles Canham and Lora Murphy of the Cary Institute of Ecosystem Studies, Millbrook, New York to start a SORTIE research program in the transitional interior cedar hemlock forests of northwestern BC as part of the Date Creek Experiment.
As part of the development of SORTIE/BC, further sub-models were added, including a disturbance module that allowed different types of partial cutting and planting. Because of the many changes being made to the model, SORTIE/BC was restructured and reprogrammed in C++ in the early 2000s. The result is SORTIE-ND where ND signifies the model’s focus on local neighbourhood dynamics. The SORTIE-ND model, code, user manual, and other useful information reside at http://www.sortie-nd.org/. Users and developers of the model can keep in contact through this site.