Modelling deadwood supply for biodiversity conservation: Considerations, challenges and recommendations

There are concerns that deadwood supply (both snags and downed wood) may become a limiting resource for biodiversity conservation as the bio-economy develops. Despite this concern, it remains difficult to monitor all elements of biodiversity to ensure that forest management activities are not reducing deadwood below minimum thresholds. As a dynamic resource, deadwood quantity and quality does change throughout forest succession. Simulation modelling represents one approach to integrating this variability and supporting the refinement of forest management guidelines. In this paper, we review important considerations for developing deadwood models that address biodiversity concerns. These include defining initial conditions, estimating deadwood inputs over time, identifying parameters necessary to represent biodiversity, identifying data available to parameterize, calibrate and validate models, and identifying requirements for model validation and documentation. In addition, we consider how deadwood characteristics such as form, size, state of decay, tree species, cause of mortality and position can be treated in models to represent the full range of biodiversity requirements. Lastly, we review examples of stand-alone and study-specific deadwood modelling approaches to provide a road map for development of a robust, temporally dynamic deadwood model that addresses biodiversity and sustainability issues related to biomass harvest for bioenergy.