Timber volume estimation based on airborne laser scanning \u2014 comparing the use of national forest inventory and forest management inventory data

Johannes Rahlf,Rasmus Astrup,Marius Hauglin,Johannes Breidenbach

doi:10.1007/s13595-021-01061-4

Johannes Rahlf, Rasmus Astrup + Show 2 more

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https://doi.org/10.1007/s13595-021-01061-4

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Abstract

Key messageLarge-scale forest resource maps based on national forest inventory (NFI) data and airborne laser scanning may facilitate synergies between NFIs and forest management inventories (FMIs). A comparison of models used in such a NFI-based map and a FMI indicate that NFI-based maps can directly be used in FMIs to estimate timber volume of mature spruce forests.ContextTraditionally, FMIs and NFIs have been separate activities. The increasing availability of detailed NFI-based forest resource maps provides the possibility to eliminate or reduce the need of field sample plot measurements in FMIs if their accuracy is similar.AimsWe aim to (1) compare a timber volume model used in a NFI-based map and models used in a FMI, and (2) evaluate utilizing additional local sample plots in the model of the NFI-based map.MethodsAccuracies of timber volume estimates using models from an existing NFI-based map and a FMI were compared at plot and stand level.ResultsEstimates from the NFI-based map were similar to or more accurate than the FMI. The addition of local plots to the modeling data did not clearly improve the model of the NFI-based map.ConclusionThe 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.

Highlights

Forest management inventories (FMIs) in the Nordic countries (Næsset et al 2004) mainly provide standlevel information in order to support forest management decisions, while national forest inventories (NFI) mainly provide statistics for reporting and policy making on regional to national scale (Tomppo et al 2010; Vidal et al.Extended author information available on the last page of the article.2016)
To analyze if the national forest inventory (NFI)-based model could be improved by using additional local sample plots, we fitted models based on a combination of the NFI data and either all or a subset of the forest management inventories (FMIs) data
We compared the accuracies of a NFI model, as it is used in a NFI-based map linking airborne laser scanning (ALS) data and NFI sample plots, and local FMI models for timber volume of mature spruce

Summary

Introduction

Forest management inventories (FMIs) in the Nordic countries (Næsset et al 2004) mainly provide standlevel information in order to support forest management decisions, while national forest inventories (NFI) mainly provide statistics for reporting and policy making on regional to national scale (Tomppo et al 2010; Vidal et al.Extended author information available on the last page of the article.2016). FMIs and NFIs have been completely separate activities but the increasing availability of fineresolution remotely sensed 3D data such as large-scale or even nationwide airborne laser scanning (ALS) campaigns has triggered the creation of detailed national forest resource maps, and as a consequence, the search for synergies between NFIs and FMIs (Kangas et al 2018a). Sensed data from ALS or digital aerial photogrammetry allow accurate estimation of forest stand parameters (Rahlf et al 2014) to support forest management decisions (Kangas et al 2018b). In the Nordic countries, ALS is currently the most common method for the acquisition of auxiliary data in FMIs (Næsset 2014; Maltamo et al 2021). Common steps in an ALS-based FMI are (1) manual stand delineation, (2) stratification of the stands into four or more treespecies and maturity-class-specific strata, (3) ALS data

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