A tree hollow dynamics simulation model

This paper describes a deterministic computer model for simulating forest dynamics. The model predicts the long-term dynamics of hollow-bearing trees which occur in a single-species (monotypic) forest stand under an array of different timber harvesting regimes over a time scale of centuries. It is applied to a number of different timber harvesting scenarios in the mountain ash (Eucalyptus regnans F. Muell.) forests of Victoria, south-eastern Australia. Computer experiments give results that have far-reaching implications for forest management and could not have easily been predicted without a model. These include: (1) when the harvest rotation time is 100 years or less, a supply of trees with hollows cannot be ensured by only retaining trees which already have hollows: and (2) when some retained trees are lost through logging-related mortality, the effect on the number of trees with hollows is exaggerated. For instance, if half of the retained trees are lost via logging-related mortality, it is not sufficient to double the number of trees retained in order to maintain the same number of hollow-bearing trees. HOLSIM is a planning tool for forest and wildlife managers, it will assist them in forecasting long-term stand conditions that result from particular forest management regimes. The ability to make predictions over several harvesting cycles is extremely important for examining the effects of harvesting strategies on the dynamics and structure of forest ecosystems, determining if given management strategies will meet particular targets, anticipating the impacts of forestry operations on hollow-dependent fauna, and helping to better integrate biodiversity conservation within wood production forests.