SORTIE-ND

History of the SORTIE-ND Model in British Columbia

SORTIE-ND 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 1990's 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 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. The Date Creek Research Forest offered a wealth of data and a well organized infrastructure for collecting new data as research questions emerged. Unique ecological aspects of these northern temperate forests along with a greater emphasis on forest management considerations were incorporated into the modeling research and SORTIE/BC was developed (Coates et al. 2003). The core SORTIE-related papers from this research programme are Kobe and Coates 1997, Wright et al. 1998, Canham et al. 1999, LePage et al. 2000, Wright et al. 2000, Canham et al. 2004, Coates et al. 2009 

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, users manual and other useful information reside at http://www.sortie-nd.org/. Users and developers of the model can can keep in contact through this site.  


SORTIE-ND simulates changes in tree populations over time. The model uses a combination of empirical and mechanistic behaviours to predict forest dynamics based on field experiments that measure fine-scale and short-term interactions among individual trees. All field studies operate at the neighbourhood scale of forest dynamics. SORTIE-ND is designed to provide growth predictions for individual trees in multi-species complex structured stands. It has a much higher degree of flexibility in terms of which processes (termed behaviours) are set to act on a population of trees. SORTIE-ND encapsulates the emerging theory of neighbourhood dynamics, where interactions among individual trees and their spatially heterogeneous environment are inherently local in nature acting at a scale over restricted distances. All model behaviours and related parameters are user-specified and the model can be fitted to a wide range of specific conditions. SORTIE-ND has an intermediate position between purely empirical and process-based models.


Since the mid-2000s the focus of the SORTIE-ND research programme in northern BC shifted to issues around projecting stand dynamics after the massive Mountain Pine Beetle (MPB) epidemic in the sub-boreal spruce forests of central BC. This research programme has been undertaken by the Bulkley Valley Research Centre and the BC Forest Service and has included the establishment of a series of new experiments and large stem-mapped plots in sub-boreal forests. We have also placed a greater emphasis on model evaluation for management predictions. Recently published papers from this research include Astrup et al. 2008a, Astrup et al. 2008b, and Thorpe et al. 2010. See also Coates et al. 2006 and Coates et al. 2009 for descriptions of stand structure and secondary structure after mountain pine beetle attack in northern forests. For ongoing studies in sub-boreal forests see Current Research Projects.   

Please see Our Collaborators for a listing of researchers working on SORTIE-ND related research in northern British Columbia either directly through the Bulkley Valley Research Centre or the BC Forest Service, or in collaboration with the BV Centre or the BCFS.