Value of airborne laser scanning and digital aerial photogrammetry data in forest decision making

Abstract

Highlights• Airborne laser scanning (ALS) and digital aerial photogrammetry (DAP) are nearly equally valuable for harvest scheduling decisions even though ALS data is more precise.• Large underestimates of stand volume are most dangerous errors for forest owner because of missed cutting probabilities.• Relative RMSE of stand volume and the mean volume in a test area explain 77% of the variation between the expected losses due to errors in the data in the published studies.• Increasing the relative RMSE of volume by 1 unit, increased the losses in average by 4.4 € ha -1 . AbstractAirborne laser scanning (ALS) has been the main method for acquiring data for forest management planning in Finland and Norway in the last decade. Recently, digital aerial photogrammetry (DAP) has provided an interesting alternative, as the accuracy of stand-based estimates has been quite close to that of ALS while the costs are markedly smaller. Thus, it is important to know if the better accuracy of ALS is worth the higher costs for forest owners. In many recent studies, the value of forest inventory information in the harvest scheduling has been examined, for instance through cost-plus-loss analysis. Cost-plus-loss means that the quality of the data is accounted for in monetary terms through calculating the losses due to errors in the data in the forest management planning context. These costs are added to the inventory costs. In the current study, we compared the losses of ALS and DAP at plot level. According to the results, the data produced using DAP are as good as data produced using ALS from a decision making point of view, even though ALS is slightly more accurate. ALS is better than DAP only if the data will be used for more than 15 years before acquiring new data, and even then the difference is quite small. Thus, the increased errors in DAP do not significantly affect the results from a decision making point of view, and ALS and DAP data can be equally well recommended to the forest owners for management planning. The decision of which data to acquire, can thus be made based on the availability of the data on first hand and the costs of acquiring it on the second hand.

Structure from Motion Photogrammetry in Forestry: a Review

“…Three-dimensional (3D) RS data, which can describe tree or canopy height, have shown great potential for forest inventory [4]. In the past 20 years, the use of airborne laser scanning (ALS) has been widely used for forest inventory purposes and has become the standard data source for operational forest inventories in many countries around the world [5][6][7]. Nevertheless, the acquisition of ALS data requires a degree of planning and investment, making these data sources cost-effective only on a relatively large scale [8].…”

“…This data synergy has been thoroughly discussed by Goodbody et al [11], indicating the potential for cost-efficient forest inventory updates. Similarly, Kangas et al [6] suggest an equal value of photogrammetric and ALS data in forest management planning, given that a ALS ground information is available from previous campaigns. Additional to the proven complementary use of LiDAR and photogrammetric data [9,11,12], recent attempts at deriving inventory relevant forest metrics from photogrammetric data alone show potential for aerial [13•, 14] and terrestrial [15•, 16] acquisitions.…”

Detection of necrotic foliage in a young Eucalyptus pellita plantation using unmanned aerial vehicle RGB photography – a demonstration of concept

“…In particular, a substantial research effort has been directed at assessing the capability of photogrammetric methods to generate canopy and tree-level metrics that support estimation of forest inventory (Nurminen et al 2013;White et al 2015;Bonnet et al 2017;Goodbody et al 2017;Ota et al 2017;Alonzo et al 2018;Caccamo et al 2018;Guerra-Hernández et al 2018;Navarro et al 2018;Iqbal et al 2019). These studies have demonstrated that DAP and photogrammetric methods are a practical alternative to airborne laser scanning (ALS) for the purposes of forest inventory when there are sufficient operational and financial benefits (Kangas et al 2018).…”

Economic losses caused by tree species proportions and site type errors in forest management planning

“…The value of the information contained in forest inventory data can be examined using cost-plus-loss (CPL) analysis (Hamilton 1978;Burkhart et al 1978), in which the losses due to non-optimal decisions caused by inaccurate data are added to the total costs of the forest inventory (Eid 2000;Borders et al 2008;Duvemo 2009;Islam et al 2009;Mäkinen et al 2012;Kangas et al 2018a). Losses occur when sub-optimal decisions are made because of erroneous data, and their magnitudes usually increase with the uncertainty of the data.…”

“…Recently, the interest has been more in three-dimensional digital aerial photogrammetry data (3D), which have been seen as a promising and clearly cheaper data source than ALS data (e.g. Ørka et al 2013;Kangas et al 2018a). However, the use of three-dimensional aerial data necessitates an available digital terrain model.…”