Management objectives for forest values are typically modelled in timber supply analyses. The objectives usually apply to the entire forest area within a particular management emphasis area and/or landscape unit. This forest area includes areas suitable for timber harvesting as well as forested areas assumed to be unavailable for harvest (the non-timber harvesting land base or non-THLB). This paper presents some approaches for modelling the role of natural disturbance such as wildfire & insect infestation within the non-THLB, most of which have been previously employed in timber supply analyses in British Columbia. Modelling details, critical comments, and examples of use of the model are reviewed for the following options: continuous ageing of the non-THLB; maintaining a static age class distribution in the non-THLB; uniform age reset on the entire forested non-THLB; age reset by variant in forested non-THLB; ignoring seral requirements; ignoring the contribution of the non-THLB; age class recycling; and stochastic disturbance modelling.