Terrestrial Laser Scanning for Plot-Scale Forest Measurement

Glenn J Newnham,F Mark Danson,Mathias I Disney,John D Armston,Kim Calders,Crystal B Schaaf,Jenny L Lovell,Alan H Strahler

doi:10.1007/s40725-015-0025-5

Abstract

Abstract Plot-scale measurements have been the foundation for forest surveys and reporting for over 200 years. Through recent integration with airborne and satellite remote sensing, manual measurements of vegetation structure at the plot scale are now the basis for landscape, continental and international mapping of our forest resources. The use of terrestrial laser scanning (TLS) for plot-scale measurement was first demonstrated over a decade ago, with the intimation that these instruments could replace manual measurement methods. This has not yet been the case, despite the unparalleled structural information that TLS can capture. For TLS to reach its full potential, these instruments cannot be viewed as a logical progression of existing plot-based measurement. TLS must be viewed as a disruptive technology that requires a rethink of vegetation surveys and their application across a wide range of disciplines. We review the development of TLS as a plot-scale measurement tool, including the evolution of both instrument hardware and key data processing methodologies. We highlight two broad data modelling approaches of gap probability and geometrical modelling and the basic theory that underpins these. Finally, we discuss the future prospects for increasing the utilisation of TLS for plot-scale forest assessment and forest monitoring.

Highlights

Forest Plot MeasurementPlot-scale forest measurements have been the basis for commercial forest inventory since the late eighteenth century [1]
The use of gap probability and variable radius plots to characterise forests requires only a single scan, which remains very attractive for forest mensuration and large-area sampling, but the resulting metrics are often indirectly related to the feature of interest and conceptually difficult to accept for those accustomed to traditional forest surveys
There are examples of permanently deployed terrestrial laser scanning (TLS) instruments designed to monitor forest structural change over time [74, 75] and linking time series of structural measurements to ecological drivers [76]. While these instruments give up some performance in terms of maximum range, angular resolution and positional accuracy, they can be a useful tool for gap probability–based characterisation of forest plots

Summary

Introduction

Plot-scale forest measurements have been the basis for commercial forest inventory since the late eighteenth century [1]. The use of gap probability and variable radius plots to characterise forests requires only a single scan, which remains very attractive for forest mensuration and large-area sampling, but the resulting metrics are often indirectly related to the feature of interest and conceptually difficult to accept for those accustomed to traditional forest surveys Future developments in both hardware and data processing methods will help to create synergies from both approaches. There are examples of permanently deployed TLS instruments designed to monitor forest structural change over time [74, 75] and linking time series of structural measurements to ecological drivers [76] While these instruments give up some performance in terms of maximum range, angular resolution and positional accuracy, they can be a useful tool for gap probability–based characterisation of forest plots. The system has been tested in forest environments with some preliminary assessment of the results relative to conventional TLS [81]

Methods

Findings

Conclusions