The article presents a state of art of forest decline inventories in Slovenia. The first part deals with methodological and technological aspects of forest health inventories, while the second one describes some hints and directions of further forest inventories development.

The Forest Research Plot was chosen on a typical site for the Pokljuka plateau. It is covered by a supposedly autochthonous old Norway spruce stand with rejuvenation centres. Data on the physiological parameters can be used as representation values for a subalpine Norway spruce stand. The studies include: standard site and dendrological parameters, physiological parameters (foliar analysis, antioxidants, hormones and aminoacids in spruce needs), genetical and biochemical analysis (isoenzymes and molecular markers), microbiological activity (acid phosphatase, rate of decomposition, number and occurrence of fungal decomposers of wood and litter) and studies of symbionts and pathogens of Norway spruce (mapping of fruitbodies of mycorrhizal fungi, types of ectomycorrhizae, endophytes, epiphytes - lichens and phytopathological surveys). All physiological and ecological studies are planned to be repeated at certain time periods in order to understand better the functioning of the forest ecosystems on Pokljuka.

This paper deals with presenting a broad range of possibilities, which can be used with computer equipment by deriving, interpreting and processing forest data. Different rates of generalized data from the forest inventory can be used as a criterion in preparing different solutions. So this data strongly influences decision making processes. The paper also presents cost analysis and multi-criteria evaluation methods.

The evaluation of data on the forest tree condition is weak point in forest decline monitoring as it enables only a very rough estimation of the state of forest health. The paper analyses the interpretation of the forest tree defoliation data in order to estimate their relevance and applicability. Quality control results of defoliation assessment in Slovenia are presented and the state of defoliation with its changes in the year 1987, 1991, 1993, 1994 on the 16 km grid.