Forest policy and management traditionally rely on physical forest data from National Forest Inventories (NFIs). Nationwide questionnaire surveys on the other hand provide information on the relationship between the human population and the forest, but data on the link to the physical forest is missing. In order to monitor outdoor recreation, both are needed. The aim of the present study is to bridge this gap by conducting a forest visitor survey in the vicinity of NFI sample plots and linking questionnaire data and NFI data in a multilevel model to determine the visual attractiveness of the forest plots in both winter and summer. In addition to traditional NFI measurements, visibility range was determined by terrestrial laser scanning (TLS). The results show that visual attractiveness was mainly determined by the individual characteristics of forest visitors. Although forest plots were generally liked better in summer, major seasonal differences between forest characteristics were limited to a few parameters, and differences in the characteristics of winter and summer visitors were small. Non-seasonal plot-specific variables played a greater role in explaining visual attractiveness than seasonal differences within the forest plots. TLS proved to be a sophisticated and reliable, but time-consuming, method for determining visibility range. We conclude that the resource-intensive on-site survey yielded interesting results, but that intangible factors and confounding effects made it difficult to pinpoint exactly which features determine forest attractiveness. Future monitoring of forest recreation should aim to strengthen the link between physical forest monitoring, as conducted in NFIs, and socio-cultural forest monitoring. To address the question which methods are suitable to link socio-cultural forest monitoring with an National Forest Inventories (NFI), we recomment to use photos from NFI plots in an online questionnaire survey instead of an on-site study. Although many variables were used in both studies, their explanatory value was considerably lower in the on-site survey than in the online survey. Future on-site studies should aim to capture intangible factors and confounding effects by including more qualitative research, for example by employing Go-Along interviews or visitor-employed photography, in order to provide in-depth information on which social factors should be included in future monitoring approaches. Including standardised visualisations of NFI plots in each round of socio-cultural forest monitoring together with a set of NFI variables relevant for recreation and visual attractiveness could form the missing link between NFIs and socio-cultural forest monitoring.
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