Multisource Single-Tree Inventory in the Prediction of Tree Quality Variables and Logging Recoveries

Abstract

Abstract:The stem diameter distribution, stem form and quality information must be measured as accurately as possible to optimize cutting. For a detailed measurement of the stands, we developed and demonstrated the use of a multisource single-tree inventory (MS-STI). The two major bottlenecks in the current airborne laser scanning (ALS)-based single-tree-level inventory, tree detection and tree species recognition, are avoided in MS-STI. In addition to airborne 3D data, such as ALS, MS-STI requires an existing tree map with tree species information as the input information. In operational forest management, tree mapping would be carried out after or during the first thinning. It should be highlighted that the tree map is a challenging prerequisite, but that the recent development in mobile 2D and 3D laser scanning indicates that the solution is within reach. In our study, the tested input tree map was produced by terrestrial laser scanning (TLS) and by using a Global Navigation Satellite System. Predictors for tree quality OPEN ACCESSRemote Sens. 2014, 6 3476 attributes were extracted from ALS data or digital stereo imagery (DSI) and used in the nearest-neighbor estimation approach. Stem distribution was compiled by summing the predicted single-tree measures. The accuracy of the MS-STI was validated using harvester data (timber assortments) and field measures (stem diameter, tree height). RMSEs for tree height, diameter, saw log volume and pulpwood volume varied from 4.2% to 5.3%, from 10.9% to 19.9%, from 28.7% to 43.5% and from 125.1% to 134.3%, respectively. Stand-level saw log recoveries differed from −2.2% to 1.3% from the harvester measurements, as the respective differences in pulpwood recovery were between −3.0% and 10.6%. We conclude that MS-STI improves the predictions of stem-diameter distributions and provides accurate estimates for tree quality variables if an accurate tree map is available.

Outlook for the Next Generation’s Precision Forestry in Finland

“…For example, in ABA, stem-quality attributes required by the forest industry, such as species-specific timber assortments, cannot be obtained accurately [5,[8][9][10]. Single tree-level information would be required to solve the above-mentioned limitations [11,12]. Thus, there is growing interest for more detailed forest measurements.…”

“…With existing tree map and tree-species information, airborne 3D data are used in extraction of predictors for tree quality variable update. In our investigations, multisource single tree inventory (MS-STI, Figure 3) has provided accuracies that have been unobtainable by ABA or traditional ALS-based single-tree inventories [11,12]. Ground truth for MS-STI can be obtained by MLS measurements from harvester and harvester crane measurements.…”

Characterizing the Height Structure and Composition of a Boreal Forest Using an Individual Tree Crown Approach Applied to Photogrammetric Point Clouds

“…For structural attribute quantification, both ABA and ITC can now achieve results of relatively high accuracy. However, for more species-specific attributes estimations in mixed forests, it can be argued that ABA reaches limitations and ITC methods can theoretically produce more detailed information [12,13] because the point cloud characteristics of individual trees can be linked to species-specific features, such as crown shape, porosity or reflectance [7,14]. ABA on the other hand can only describe overall point cloud features on a plot or stand basis, leading to substantial ambiguity when multiple species are present.…”

Estimation of the Timber Quality of Scots Pine with Terrestrial Laser Scanning

“…The measurement procedure should be fully automatic before it can be used in operational forestry. A combination of ALS, TLS and also mobile laser scanning (MLS) could be a viable option in tree quality estimation (e.g., [53]). …”