A tree hollow dynamics simulation model

Abstract

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, southeastern Australia. Computer experiments give results that have farreaching 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 hollowbearing trees. HOLSIM is a planning tool for forest and wildlife managers. it will assist them in forecasting longterm 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.

Does hollow occurrence vary with forest type? A case study in wet and dry Eucalyptus obliqua forest

“…Many animal species use tree hollows or cavities as nesting or roosting sites (Smith and Lindenmayer, 1988;Bai et al, 2003;Gerhardt, 2004;Kalcounis-Ruppell et al, 2005;Walker et al, 2005) but there is concern about the future availability of the hollow resource, particularly in areas of production forestry (Gibbons and Lindenmayer, 1996;Ball et al, 1999;Fan et al, 2004). One of the concerns with production forestry is that it reduces the age of the stand and, therefore, the availability of hollows (Lindenmayer et al, 1990a;Gibbons and Lindenmayer, 1996).…”

Four issues influencing the management of hollow-using bats of the Pilliga forests of inland New South Wales

“…Modelling forest stand dynamics for a range of tree species, e.g. as done by Ball et al (1999) for Mountain Ash forest, should also be given high priority. Models should be progressively refined as data become available from four projects that should be run concurrently: a) Historical stand structure.…”

Identifying bias in stand-level growth and yield estimations: A case study in eastern Brazilian Amazonia

“…Most published studies of defective trees have been conducted in Australia, focusing mainly on hollowed trees from the genus Eucalyptus (Gibbons and Lindenmayer, 1996;Ball et al, 1999;Lindenmayer et al, 2000;Whitford, 2002). In the absence of detailed information on hollow trees in the Amazon (i.e., species-specificity, DBH-specificity, relationship to growth or mortality), we assumed that defective trees do not demonstrate different growth or mortality rates from defect-free trees, and that they are randomly distributed among all trees in the study forest.…”