Although thinning originated as a man-made forest management tool, aimed at increasing timber yields, the shift from production forests to multifunctional forests brought with it the cutting of trees to manipulate an ecosystem for various reasons, ranging from removing non-native species from a plot to removing poplars growing on a riverside beach aimed at recreational use.
Since the 1970s, leaving the thinned trees on the forest floor has become an increasingly common policy: wood can be decomposed in a more natural fashion, playing an important role in increasing biodiversity by providing habitat to various invertebrates, birds and small mammals. Many fungi (e.g. Calocera viscosa) and mosses are saproxylic or epixylic as well (e.g. Marchantiophyta) – some moss species completing their entire life-cycle on a single log.
Where trees are managed under a commercial regime, competition is reduced by removing adjacent stems that exhibit less favourable timber quality potential. When left in a natural state trees will "self-thin", but this process can be unreliable in some circumstances. Examples of this can be found in the Buxus - Ironbark forests and woodlands of Victoria (Australia) where a large proportion of trees are coppice, resultant from timber cutting in decades gone by.
Ecological thinning research
Research programs under way in various parts of the world (e.g. USA and Australia) are aimed at providing an alternate approach in forest management where conservation objectives are a high priority. Methods of ecological thinning being developed on silvicultural techniques for local forest types. Ecological thinning is being developed using two principles: 1. appropriate stem reduction to reduce competition and 2. retention of trees (selection) that are more suitable for wildlife (i.e. not timber production). An example of ecological thinning research is the project in Victoria's Box-Ironbark forests, investigating various thinning and timber removal methods under an Adaptive Management or AEM framework. The primary objective is to generate (over time) a number of forest habitat values (i.e. tree hollows) that are crucial for wildlife conservation.
- Parks Victoria Box-Ironbark Parks & Reserves - follow link to thinning trial FAQ
- Ecological Thinning Conference Poster - Poster presented to ESA2004 in Adelaide, Australia
- Review of Thinning Prescriptions - Review of thinning in park management in Australia
- Cedar River Watershed Habitat Conservation Plan - Catchment project in Seattle, USA