Department of Forest Resources and Environmental Conservation
 

Valerie Thomas - Assistant Professor

Teaching Responsibilities

  • FOR/GEOG 6214: Forestry Lidar Applications
  • FOR/GEOG 5154: Hyperspectral Remote Sensing of Natural Resources
  • FOR 2984: Forests, Society, & Climate

Selected Research Activities

  • Remote Sensing for Forest Physiology and Structure.  My primary research focus involves the use of remote sensing to examine canopy physiology and structure.  In particular, I focus on the use of light detection and ranging data (lidar) to examine forest structure, canopy architecture and the forest light regime.  I use hyperspectral remote sensing to investigate foliar biochemistry (chlorophyll, nitrogen, phosphorus, magnesium, potassium, and calcium), canopy photosynthesis parameters, and indicators of health and vigor.  Combined, these two remote sensing technologies tell us much more about the structure and function of a forest than is possible with any other type of remote sensing.  These data and insights are used to model carbon stocks and carbon exchange.  Of particular interest is the potential response of forest ecosystems to environmental stressors, such as climate change, insect infestation, deforestation, and other types of disturbance. 

  • Ecosystem Services for Biodiversity.  We are developing a remote-sensing-based ecosystem services calculator, Biodiversity 1.0, using wildlife-habitat databases that are based on inferences from literature, field biodiversity data of plant and animal species, and their known habitat associations.    The tool is based on the concept that landscape features (i.e., land cover, landscape pattern, topography, etc.) are correlated with species and can be used to predict biodiversity based on known associations and regression models.  Our tool will be a module within a more comprehensive ecosystem services tool, MEASURES (Management-Scale Ecosystem Assessment using Remote Sensing), which examines the impacts of land management scenarios on carbon, water, and biodiversity.  Biodiversity 1.0 is funded by the Virginia Department of Games and Inland Fisheries.

  • Remote Sensing and the US Forest Inventory and Analysis (FIA) Program. We are integrating remote sensing with broad-scale inventory data from the FIA program in the Southern Region. Extensive and intensive land-based data sets will be linked to satellite imagery and auxiliary geospatial databases organized at multiple scales to accomplish three major objectives for this work: 1) to assess the ecological representativeness of the experimental forest network, 2) to extrapolate monitoring data to unsampled areas of the landscape, and 3) to demonstrate how EFR knowledge of cause and effect can be extrapolated to representative portions of the broader landscape.  This work is funded by the USDA Forest Service, Southern Research Station.

  • Remote Sensing of Virginia Wetlands.  We are using remotes sensing, primarily a combination of light detection and ranging (lidar) data with the 25-year Landsat time series, to detect areas of wetland disturbance, to improve the classification of wetland types as compared to the National Wetland Inventory, and to examine wetland hydroperiod and hydrologic function.  This work is part of a larger study: Pilot Assessment of Virginia Wetland Permits, funded by the Virginia Department of Environmental Quality (EPA Region III).

Selected Publications

  • Thomas, V., T. Noland, J.H. McCaughey, and P. Treitz (2010, in press). Leaf area and clumping indices for a boreal mixedwood forest: lidar and hyperspectral models. International Journal of Remote Sensing (in press). 
  • Treitz, P.M., V. Thomas, P.J. Zarco-Tejada, P. Gong, and P.J. Curran (2010). ASPRS Monograph - Hyperspectral Remote Sensing for Forestry. ASPRS Monograph Series, ISBN 1-57083-093-2, 107 pages.
  • Thomas, V., J.H. McCaughey, P. Treitz, D.A. Finch, T. Noland, T., and L. Rich, 2009. Spatial modelling of photosynthesis for a boreal mixedwood forest by integrating micrometeorological, lidar and hyperspectral remote sensing data.  Agriculture and Forest Meteorology, 149:639-654.
  • Thomas, V., R. Oliver, K. Lim, and M. Woods, 2008. Lidar and Weibull modeling of diameters and basal area distributions. The Forestry Chronicle, 84(6): 866-875.
  • Thomas, V., P. Treitz, J.H. Mccaughey, T. Noland, and L. Rich, 2008. Canopy chlorophyll concentration estimation using hyperspectral and lidar data for a boreal mixedwood forest in northern Ontario, Canada. International Journal of Remote Sensing, 29(4): 1029-1052.
  • Chasmer, L. and V. Thomas, 2008. Integrating Airborne Lidar with Eddy Covariance and Beyond: New Research within the Canadian Carbon Program. FluxLetter, The Newsletter of FLUXNET, 1(2):9-13.
  • 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, 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 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.

Conference Presentations and Posters

  • Kayastha, N. and V. Thomas, 2010. Exploring approaches to extracting lidar points for LAI estimation. Presented at the annual symposium of the Office of Geographic Information Systems and Remote Sensing, Virginia Tech.  Award 3rd prize.

  • V. Thomas, M. Khomik, J.H. McCaughey, A. Arain, and P. Treitz (2010) Leaf and Canopy Physiology: Synergistic Use of Field Measurements, Radiative Transfer Modeling, and Lidar-Hyperspectral Remote Sensing. Presented at the Canadian Remote Sensing Symposium, Prairie Summit in June 2010.

  • Gökkaya, K., Thomas, V., Noland, T., Wynne, R., McCaughey, H., Morrison, I., and Treitz, P. 2009. Prediction of Foliar Biochemistry Using Canopy Reflectance and Structure Information. 30th Canadian Symposium on Remote Sensing. 22-25 June, 2009. Lethbridge, AB, Canada.

  • Kayastha, N. and V. Thomas, 2009. Exploring approaches to extracting lidar points for LAI estimation. Presented at the Silvilaser 2009 in College Station, Texas.

  • Thomas, V., T. Noland, J.H. McCaughey, and P. Treitz. 2009. Lidar-hyperspectral analysis to examine leaf area index, clumping, and canopy biochemistry in a boreal mixedwood environment.  Presented at the ASPRS 2009 Annual Conference, March 9-13, 2009. Baltimore, Maryland.

  • Banskota, A., R.H. Wynne, P. Johnson, B. Emessiene, V.Thomas, 2008. Synergistic use of very high frequency radar and profiling lidar for estimating biomass in hardwood and mixed forests. 2008 IEEE International Geoscience & Remote Sensing Symposium, July 6-11, Boston, Massachusetts, USA.

  • Thomas, V. 2008. Lidar-derived assessments of primary productivity and photosynthetic capacity. Changing Land Base Section, Society of American Foresters 2008 National Convention, Nov. 5-9, 2008, Reno, Nevada.

  • Quirino, V.F., R.H. Wynne, J.R. Seiler, and V. Thomas, 2008. How much variability in soil respiration can remotely sensed forest structure explain? AGU, 89(53), Fall Meet. Suppl., Abstract B41A-0352.

  • Banskota, A., R.H Wynne, V. Thomas, N. Kayastha, and A. Peduzzi, 2008. Predicting biomass in temperate hardwood and mixed forests using VHF radar, interferometric SAR and discrete-return lidar data. EOS Trans. AGU, 89(53), Fall Meet. Suppl., Abstract B32A-06.

  • Thomas, V., J.H. McCaughey, P.M. Treitz, and T. Noland, 2008. Integration of lidar and hyperspectral remote sensing to examine the influence of tree species arrangements on site estimates of biophysical variables, LAI, fPAR, and GPP. EOS Trans. AGU, 89(53), Fall Meet. Suppl., Abstract B32A-05.

  • Peduzzi, A., V. Thomas, R.H. Wynne, and T. Fox, 2008. Estimation of leaf area using imaging lidar data in intensively and extensively managed temperate forests. EOS Trans. AGU, 89(53), Fall Meet. Suppl., Abstract B41A-0349.

  • Thomas, V., J.H. McCaughey, P.M Treitz, D.A. Finch, and T. Noland, 2006. Spatial Variability at the Groundhog River Flux Site. Poster presentation at the Fluxnet-Canada 2006 Annual General Meeting, Victoria, British Columbia, Feb. 24-26, 2006.

  • McQueen, S., K. Mahoney, J.H. McCaughey, M.A. Arain, A. Cameron, R. Dexter, D.A. Finch, L. MacLean, M. Pejam, V. Thomas,  and P. Treitz, 2006. 2004-2005 Carbon and Energy Exchange in the Ontario Mixedwood Forest. Poster presentation at the Fluxnet-Canada 2006 Annual General Meeting, Victoria, British Columbia, Feb. 24-26, 2006.

  • Thomas, V., D. Finch, J.H. McCaughey, P. Treitz, T. Noland, and L. Rich, 2005. Modelling below-canopy PAR for a mixed-wood boreal forest environment. Presented at the Canadian Association of Geographers Annual General Meeting, London, Ontario (May 29-June 3, 2005). 

  • Thomas, V., J.H. McCaughey, and P. Treitz, 2005.  Modelling Photosynthesis at the Groundhog River Flux Station: Preliminary Results. Poster presentation at the Fluxnet-Canada 2005 Annual General Meeting, February 25-27, 2005, Quebec City.

  • Thomas, V., J.H. McCaughey, P. Treitz, D.A. Finch, I. Morrison, T. Noland, and L. Rich, 2005.  Preliminary results of the 2003-2004 sampling of canopy characteristics at the Groundhog River Flux Station. Presented at the Fluxnet-Canada 2005 Annual General Meeting, February 25-27, 2005, Quebec City.

  • McCaughey, J.H., M.A. Arain, A. Cameron, M. Khomik, L. MacLean, M. Pejam, V. Thomas, and  P. Treitz, 2005.  Carbon, water, and energy exchange in the Ontario mixedwood forest region. Poster presentation at the Fluxnet-Canada 2005 Annual General Meeting, February 25-27, 2005, Quebec City.

  • McCaughey, J.H., M.A. Arain, A. Cameron, L. Chasmer, D.A. Finch, M. Khomik, L. MacLean, I. Morrison, M. Pejam, V. Thomas, and  P. Treitz, 2005.  Progress report of the Groundhog River Flux Station (Ontario) 2004. Poster presentation at the Fluxnet-Canada 2005 Annual General Meeting, February 2005, Quebec City.

  • Thomas, V., J.H. McCaughey, and P. Treitz, 2004. Preliminary work toward the estimation of canopy carbon uptake:  Large tree characterization of the Groundhog River flux station, Ontario. Poster presentation at the Fluxnet-Canada 2004 Annual General Meeting, February 2004, Banff.

  • Thomas, V., J.H. McCaughey, and P. Treitz, 2004. Preliminary work toward the estimation of canopy carbon uptake through the integration of flux tower measurements, hyperspectral and lidar remote sensing. Presented atthe Fluxnet-Canada 2004 Annual General Meeting, February 2004, Banff.

  • Thomas, V., P. Treitz, and J.H. McCaughey, 2003. Modelling photosynthesis of a boreal forest; an integrated remote sensing approach. Poster presentation at CRESTech Innovation 2003.  September 2003, Toronto.

  • Thomas, V. and P. Treitz, 2002.  Hyperspectral Indices of Acer saccharum Forest Structure.  Poster presentation at CRESTech Innovation 2002.  September 2002, Toronto.

  • Treitz, P., K. Lim, V. Thomas, and A. Groot, 2002. LiDAR and Hyperspectral Data for Assessment of Stand Structure and Function.  Presented at the International Workshop on Three-dimensional Analysis of Forest Structure and Terrain using LiDAR technology.  Victoria, BC, March 14-15, 2002.

  • Thomas, V. and P. Treitz.  2001.  Hyperspectral Assessment of Acer saccharum Stand Structure. Poster presentation at CRESTech Innovation 2001. September 2001, Toronto.

  • Thomas, V., and P. Treitz, 2001. CASI Hyperspectral Analysis of Acer saccharum Stand Structure, Proceedings, 23rd Canadian Symposium on Remote Sensing, Sainte-Foy, Québec, August 21-24.

  • Thomas, V., and P. Treitz, 2001. Hyperspectral Assessment of Sugar Maple Stand Structure, Third North American Forest Ecology Workshop, Measuring and Monitoring Forest Ecosystem Health Session, Duluth, MN, June 21-24.

  • Maher, B., V. Thomas, and S. Rawlinson, 1999. Canadian Involvement in the Design and Delivery of the New M.Sc. in Information Technology for Natural Resources Management, Biotrop, IPB,Indonesia.  1999 International Cartographic Association Conference, July 1999, Ottawa.

  • Thomas, V. and P. Treitz.  2000.  Characterization of Acer saccharum for Analysis With CASI Hyperspectral Data. Presented at the Ice Storm 1998 Forest Damage Research Conference, October 2000, Ottawa.

  • Thomas, V. and P. Treitz.  2000.  Development of Hyperspectral Structural Indices for Acer saccharum: Preliminary Work.  Poster presentation at CRESTech Innovation 2000.  September 2000, Toronto.

  • Thomas, V., P. Treitz, and D. Jelinski, 2000. Use of Species Abundance Data for Classification of High Spatial Resolution CASI Imagery for a Northern Manitoba Fen, Program and Abstracts, Canadian Association of Geographers 2000 Annual Conference, Brock University, St. Catharines, Ontario, May 31 to June 3.

  • Treitz, P., P. Sampson, and V. Thomas, 2000. Remote Sensing of Forest Structure and Function, Program and Abstracts, Canadian Association of Geographers 2000 Annual Conference, Brock University, St. Catharines, Ontario, May 31 to June 3.

  • Thomas, V., P. Treitz, and D. Jelinski, 2000. Use of Species Abundance Data for Classification of High Spatial Resolution CASI Imagery for a Northern Manitoba Fen, Program and Abstracts, Canadian Association of Geographers 2000 Annual Conference, Brock University, St. Catharines, Ontario, May 31 to June 3.

  • Maher, B., V. Thomas, and S. Rawlinson, 1999. Canadian Involvement in the Design and Delivery of the New M.Sc. in Information Technology for Natural Resources Management, Biotrop, IPB,Indonesia.  1999 International Cartographic Association Conference, July 1999, Ottawa.