Bulkley Valley Research Centre - Science in the Public Interest

LIDAR

Project Reference Number: 2008-22

Project Status: Complete

Led by: Dave Coates, PhD, Research Silviculturist, Ministry of Forests, Lands and Natural Resources, Smithers

Funder: University of British Columbia

This UBC-based study in collobration with Technische Universität München (Drs. Hans Pretzsch and Stefan Seifert) and the University of New Hampshire (Dr. Mark Duecy) is being undertaken at stem-mapped sites around Smithers. Terrestrial LIDAR scans are being taken across successional and productivity gradients.  In summer 2008 the first set of scans were completed. Further scanning will take place over the next few summers. This study is only indirectly related to SORTIE-ND, however, findings from this study could result in new behaviours being added to SORTIE-ND or aid in model testing and validation.

The current focus on managing structurally complex stands requires a shift in emphasis away from non-spatial data. To better understand the role of complexity in stand dynamics and to efficiently plan management regimes that take advantage of interactions among tree species we require additional information on the key processes that determine individual tree performance. This study will provide some of the basic relationships that are required to predict growth and stand development in complex-structured stands. Additionally, this study will improve our knowledge of how terrestrial LIDAR can be applied in forest research and forest measurements.

The study investigates three dimensional crown structures in complex-structured stands and how crown structure and crown efficiency is affected by a gradient of competition and below-ground resources. The study will quantify crown structures with terrestrial LIDAR technology and create a spatial 3D model of all individual trees in each scanned plot. The 3D crown information in combination with measures of resource availability will allow tests of hypothesises related to competition and crown efficiency and the development of predictive equations of crown development and tree growth.

Tree growth in complex-structured stands is affected by intra- and inter-specific competition for growing space, site-specific nutrient and moisture availability, and spatial pattern of neighborhood trees of different canopy positions (e.g. Kobe 2006, Coates et al. 2009). To predict stand development and growth of complex-structured stands we need to understand how these factors interplay. The following topics will be addressed in this study: (1) how resource availability affects species-specific crown development patterns, (2) how crown efficiency is affected by moisture or nutrient availability, (3) how variation in crown development and crown efficiency account for differentiation of stand development patterns along a resource gradient, and (4) the relation between crown size and tree growth. 

Comparision of different terrestrial LIDAR technologies.  

To our knowledge, there has been no published comparison of results obtained with terrestrial LIDAR using different scanners at identical points within the same forest stand, despite the fact that commercially available instruments such as the Riegl and the Leica differ in terms of light wavelength, beam width, and intensity. In this project, we will mitigate this methodological gap by conducting scans over identical benchmarks with both a Riegl and a Leica LIDAR platform. These benchmark scans will allow us to: (a) compare scanner performance, (b) compare algorithms for extracting tree location, stem taper, and crown shape, and (c) compare the performance of the two scanners to existing traditional tree allometry measurements. Thus, this project will not only test interesting hypotheses relating to crown dynamics but also contribute to the methodological knowledge of application of terrestrial LIDAR in forest research and measurement.

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