The sample plot-based national forest inventory (RIS-RT) has been a continuous activity at SLU (and the forest research organizations existing before SLU) since 1923. All Sweden is included except the subalpine birch forest along the mountain chain. The national forest inventory is part of Sweden’s official statistics and is maintained by the Department of Forest Resource Management (SLU-FRM). The sampling strategy combines random and fixed plots and covers the country every 5 years. Each year around 10 000 sample plots are field surveyed nationwide. Approximately 200 variables are recorded for each plot.