The density and volume of standing snags and downed wood are important determinants of habitat quality for many vertebrate and invertebrate species. The value of deadwood for a particular species further depends on the whether it is standing or on the ground, the size of each piece, and its state of decay. A challenge for forest managers is determining the quality of deadwood across the landscape, and projecting the impact of different management activities on the supply of this very important habitat element.

Services: In collaboration with the B.C. Ministry of Forests and Range and Gowlland Technologies Ltd., Cortex developed, parameterized, and tested a spatially explicit model for projecting snag and downed wood abundance and volumes in unmanaged and managed forests. This model spatially and temporally projects snag densities, decay state, and status (standing, fallen) by species, age and size class. Dynamics of tree death forming snags, snag breakage and fall rates, and decay rates for both standing stems and downed wood volumes are also tracked.

We develop scenarios that encompass both deadwood and land management objectives and tested consequent changes in forest values. Indicators assessed combined socio-economic measures - timber supply and road densities – with indicators of deadwood supply, and relative changes in wildlife habitat types.

Outcomes: The deadwood projection model is linked to spatial models of forest growth, disturbance, road building, and silviculture. Outputs were used to assess: (1) the effects of different disturbance types and forest management options on deadwood supply; (2) the efficacy of alternative deadwood management options (including snag removals) at the stand or within-stand level; and (3) the consequences of deadwood dynamics on the wildlife values of stands.

A more detailed description of the deadwood management model is available in the journal publication “Estimating the impacts of harvest distribution on road-building and snag abundance” ( 459 Kb).