Biodiversity can be measured at a number of different levels, depending on the time, resources and expertise available. For simple surveys to determine forest management practices, conservation strategies and areas requiring further study, very broad-scale survey techniques are probably adequate. At the other end of the scale, detailed surveys of local provenance and genetic variation may be needed for studies of genetic biodiversity.
No single series of indicators is adequate to summarise information on all aspects of forest biodiversity. Instead, a picture has to be built up from a range or portfolio of different indicators which together provide an approximate picture of forest biodiversity status. The decision on which series of indicators will be used for any one biodiversity assessment has to be made before developing the indicators in detail.
The following elements of forest quality form a basis for developing indicators. [Authenticity]: composition of trees; spatial variation pattern of trees with respect to age and size; continuity of forest function, proportion and type of dead timber; natural disturbance patterns, regeneration processes and strategies; management practices, mimicking natural processes, landscape approaches. [Forest Health]: health of trees; health of other flora and fauna; robustness to changing environmental conditions. [Environmental benefits]: biodiversity and genetic resource conservation; soil and watershed protection; impacts on other natural and semi-natural habitats; climatic stabilisation. [Social and economic values]: wood products; non-wood products; indirect employment and subsistance activities; recreational activities; forest as homeland for people; historical value; educational and scientific research value; cultural and aesthetic values; spiritual and religious values. [Local distinctiveness].