Airborne Laser Scanning Based Timber Volume Estimation Using National Forest Inventory and Forest Management Inventory Data – a Comparison
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Large-scale forest resource maps based on national forest inventory (NFI) data and airborne lased scanning (ALS) may facilitate synergies between NFIs and forest management inventories (FMIs). Traditionally, FMIs and NFIs have been completely separate activities. Increasing availability of detailed NFI-based forest resource maps provide the possibility to eliminate or reduce the need of field sample plot measurements in FMIs if their accuracy is similar. We aim to 1) compare the performance of a model used in a NFI-based map and models used in a FMI at plot and stand level, and 2) evaluate utilizing additional local sample plots in the model of the NFI-based map. Predictions and estimates based on models of an existing NFI-based map and an FMI were compared at plot and stand level. The improvement of the NFI-based map by adding local sample plots to NFI data was analyzed. Predictions of the NFI-based map were similarly accurate when using training data of the respectively other model for validation. When compared to independent forest inventory data, the NFI model was more accurate than the FMI. The addition of local plots did not clearly improve the NFI model. The comparison indicates that NFI-based maps can directly be used in FMIs for timber volume estimation in mature spruce stands, leading to potentially large cost savings.
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