Teaching Responsibilities

• FOR 6984 Forestry Lidar Applications
  Hyperspectral Remote Sensing for the Natural Resources (Fall 2008)

Selected Research Activities

• Scaling of canopy biophysical and physiological variables (in affiliation with the Canada Carbon Program).  Highly detailed representations of the canopy structure and ecologically meaningful variables (e.g., fPAR, LAI) are being derived from ground-based and airborne lidar and used to evaluate and modify existing reflectance-based algorithms. The influence of canopy shape, shadow, and heterogeneity (as determined by lidar) on multiple reflectance products (i.e., Landsat and/or Hyperion (30 m) à MODIS (250 m) à AVHRR (1 km)) will be investigated to the impact of sub-pixel spatial heterogeneity on coarse resolution estimates of carbon exchange.
• Modelling of canopy-scale photosynthesis through the integration of high-resolution airborne remote sensing data and micrometeorological measurements (in affiliation with Fluxnet-Canada and Queen’s University).  Light detection and ranging (lidar) data were analysed to derive models of tree structure, including: canopy height, basal area, crown closure, and average aboveground biomass.  Lidar and hyperspectral remote sensing data were used to model canopy chlorophyll and carotenoid concentrations (known to be good indicators of photosynthesis). The integration of lidar and hyperspectral data was applied to derive spatially explicit models of the fraction of photosynthetically active radiation (fPAR) absorbed by the canopy as well as a species classification for the site.  These products were integrated with flux tower meteorological measurements (i.e., air temperature and global solar radiation) collected on a continuous basis over 2004 to apply the C-Fix model of carbon exchange to the site.
• Estimation of diameter and basal area distributions using airborne lidar and Weibull modeling (in affiliation with the Ontario Ministry of Natural Resources and Lim Geomatics). This study investigates the ability to predict forest diameter distributions from lidar data using Weibull modelling for the Great Lakes-St. Lawrence forests of central Ontario.  Simple unimodal two-parameter Weibull models are predicted for all forest stands analyzed in the study.  For the most irregular multimodal diameter distribution, prediction of finite mixture models is also investigated.  

Selected Publications

Journal Publications:

• Thomas, V., Treitz, P., McCaughey, J.H., Noland, T., and Rich, L., 2007 (accepted). Canopy chlorophyll concentration estimation using hyperspectral and lidar data for a boreal mixedwood forest in northern Ontario, Canada.  Accepted by the  International Journal of Remote Sensing on February 3, 2007.
• Thomas, V., D.A. Finch, J.H. McCaughey, T. Noland, L. Rich, and P. Treitz, 2006. Spatial modelling of the fraction of photosynthetically active radiation absorbed by a boreal mixedwood forest using a lidar-hyperspectral approach. Agricultural and Forest Meteorology, Vol. 140, 287-307.
• Thomas, V., P. Treitz, J.H. McCaughey, and I. Morrison, 2006. Mapping stand-level forest biophysical variables for a mixedwood boreal forest using lidar: an examination of scanning density. Canadian Journal of Forest Research, Vol. 36, 34-47.
• Thomas, V., P. Treitz, D. Jelinski, J. Miller, P. Lafleur, and J. H. McCaughey, 2002. Image classification of a northern peatland complex using spectral and plant community data, Remote Sensing of Environment, Vol. 84, Issue 1, pp. 83-99.
• Massam, B., B. Prenzel, V. Thomas, and P. Treitz, 2000.“Quality of Life Surfaces: An Application of Two Techniques”, Journal of Geographic Information and Decision Analysis, Vol. 4, pp. 12-26. http://publish.uwo.ca/~jmalczew/gida_8.htm

Proceedings:

• Thomas, V, Treitz, P., McCaughey, J.H., Finch, D., Noland, T., Rich, L., and Morrison, I., 2006. Integration of lidar and hyperspectral data with micrometeorological measurements to develop spatially explicit models of canopy chlorophyll, fPAR, and photosynthesis. In proceedings of Silvilaser 2006, Matsuyama, Ehime (Japan), 7-10 November 2006, Shikoku Research Center and Ehime University, pp. 145-151.
• Thomas, V, Treitz, P., McCaughey, J.H., Noland, T., Rich, L., and Morrison, I., 2006. Estimating forest canopy chlorophyll concentration using complementary remote sensing technologies: lidar and hyperspectral data. In proceedings of Silvilaser 2006, Matsuyama, Ehime (Japan), 7-10 November 2006, Shikoku Research Center and Ehime University, pp. 224-230.
• Thomas, V., P. Treitz, D. Jelinski, J. Miller, P. Lafleur, and H. McCaughey, 2000. Classification of Ecological and CASI Reflectance Data for a Fen Community in Northern Manitoba, Proceedings, 22nd Canadian Symposium on Remote Sensing, Victoria, British Columbia, August 15-19.
• Thomas, V. and S.  Rawlinson , 1999.  “Integration of Colour Theory and Digital Elevation Models as an Alternative to Traditional Stereoscopic Terrain Visualization”,  Proceedings of the WECI-III The Third Workshop on Electro-Communication Information, Institut Teknologi Bandung, Indonesia.