ABSTRACT
As the most direct and conspicuous form of human impact on forest ecosystems is physical, indicators of forest structure often provide the most effective and appropriate basis for assessing management performance.
Structural indicators link changes in management activities with changes in the biodiversity we wish to conserve – either directly through the provision of suitable species habitat resources, or indirectly via the conservation of key ecological processes that depend on the structural environment of the forest.
Forest structural indicators can be distinguished into two basic kinds: (i) stand (e.g. measures of different vegetation strata and dead wood); and (ii) landscape (e.g. measures of forest extent and habitat composition and configuration) level indicators. In both cases, there are varyingly levels of empirical support regarding the relevance of different candidate indicators for different species groups and forest types around the world.
A systematic approach to selecting structural indicators for forest management should follow a series of five assessment criteria: (i) the identification of a viable set of indicators based on the practical availability of necessary expertise and technical support; (ii) the ‘responsiveness’ of candidate indicators to management actions; (iii) the ease (cost and time) with which they can be measured; (iv) their relevance to changes in forest condition and biodiversity and/or individual target species; and (v) the generality with which they can be applied across similar management systems in other landscapes and regions.
The initial selection of a set of structural indicators and appropriate indicator target levels for management is challenging, but can be assisted by drawing on expert knowledge and a review of management practices in surrounding region.
Structural indicators alone are not sufficient to characterize the biodiversity potential of a given site and additional non-structural indicators (e.g. of disturbance processes, such as fire and grazing regimes) can often make a valuable addition to assessments of management performance.
