Possibilities for harmonizing national forest inventory data for use in forest biodiversity assessments

Representatives of the national forest inventories (NFIs) of 27 European countries and the USA evaluated possibilities for a common approach to forest biodiversity reporting. The project was conducted under the auspices of COST (European Cooperation in the field of Scientific and Technical Research) Action E43, 'Harmonisation of National Forest Inventories in Europe: Techniques for Common Reporting'. Based on the analysis of responses to an initial questionnaire regarding the most ecologically important and technically feasible variables for monitoring forest biodiversity using NFI data, 16 key variables were selected. Responses to a second questionnaire consisting of six questions regarding assessment of the 16 key variables revealed that the NFIs of most responding countries already assess a large proportion of these variables. Each of the 16 variables is assessed in at least eight NFIs. However, the responses regarding assessment methods and necessary field crew expertise varied considerably. As a first example, although tree diameters at breast height (d.b.h.) are assessed by every country, there is a wide range of minimum d.b.h. thresholds from 0 mm in Finland to 12 cm in Cyprus and Switzerland. As a second example, eight countries estimated that almost all inventory variables require highly skilled forest staff with specialized training, but most countries agree that a middle level of expertise is sufficient. Despite differences in current NFI methods, overall, the results of the study indicate positive possibilities for achieving a moderate level of European-wide harmonization.