LEMMA Team Detail
 | Heather Roberts Database Administrator/GIS Analyst Dept. of Forest Ecosystems and Society Oregon State University | Mailing address: Department of Forest Ecosystems & Society Phone:Oregon State University 321 Richardson Hall Corvallis, OR 97331 (541) 750-7347 Email: |
Educational Background
B.S., 2001 (computer and information science), University of Oregon, Eugene, OR
B.S., 2001 (environmental studies), University of Oregon, Eugene, OR
Research Interests
Heather is interested in all aspects of natural resource management, and she enjoys using her technical skills to assist in the compilation and analysis of environmental data. Specific interests include: Modeling ecosystem processes at various scales; Developing large-scale database management systems; Using design patterns and object-oriented development techniques to build robust and flexible software applications.
Biography
Heather has been a database administrator and GIS analyst on the LEMMA team since 2006. She spends most of her time developing and managing the database that contains input data for the GNN models, but she also processes spatial data layers and has been designing and implementing systems for documentation. From 2001-2006 she worked as a database administrator and field technician for Dorena Genetic Resource Center, which is a Forest Service research station that specializes in breeding tree populations that are naturally resistant to invasive pathogens. In her free time, Heather likes practicing yoga; exploring the outdoors on foot, ski, or bicycle; and watching movies.
Refereed Publications
 | Ohmann, JL, MJ Gregory, HM Roberts, WB Cohen, RE Kennedy, Z Yang. 2012. Mapping change of older forest with nearest-neighbor imputation and Landsat time-series. Forest Ecology and Management 272:13-25. |
| Ohmann, JL, MJ Gregory, EB Henderson, HM Roberts. 2011. Mapping gradients of community composition with nearest-neighbour imputation: extending plot data for landscape analysis. Journal of Vegetation Science 22(4):660-676. |
Peer-Reviewed Publications
| Moeur, M, JL Ohmann, RE Kennedy, WB Cohen, Z Yang, MJ Gregory, HM Roberts, M Fiorella. 2011. Northwest Forest Plan -- status and trends of late-successional and old-growth forests from 1994 to 2008. PNW-GTR-853, Pacific Northwest Research Station, USDA Forest Service, Portland, OR. |
Technical Reports
| Grossmann, EB, JL Ohmann, J Kagan, HK May, MJ Gregory. 2010. Mapping ecological systems with a random forest model: tradeoffs between errors and bias. USGS Gap Analysis Bulletin, No. 17; February 2010; pp 16-22. |
| Grossmann, EB, JL Ohmann, MJ Gregory, HK May. 2009. Nationwide Forest Imputation Study (NaFIS) - Western Team final report. Final Report of the Nationwide Forest Imputation Study (NaFIS). |
| Grossmann, EB, J Kagan, JL Ohmann, HK May, MJ Gregory, C Tobalske. 2008. Final report on land cover mapping methods, map zones 2 and 7, Pacific Northwest ReGAP. Institute for Natural Resources, Oregon State University, Corvallis, OR. |
Other Non-Refereed Publications
| May, HK, JS Conery. 2003. FOREST: A System for Developing and Evaluating Ecosystem Simulation Models. Proceedings from Summer Computer Simulation Conference: Montreal, Quebec; July 2003. |
Presentations
 | Gregory, MJ, JL Ohmann, HM Roberts, HSJ Zald, EB Henderson. 2013. Recent advances and applications of nearest neighbors methods for regional-scale forest vegetation mapping in the Pacific Northwest, USA. Landcare Research Seminar: Lincoln, New Zealand; February 2013. |
| Zald, HSJ, JL Ohmann, HM Roberts, M Gregory, EB Henderson, R McGaughey, RE Kennedy, J Braaten, M Simpson. 2013. Incorporating LiDAR and Landsat disturbance history into nearest neighbor mapping of vegetation composition and structure. USFS Region 6 office for Monitoring Inventory Mapping and LiDAR (MIML) working group: Portland, OR; February 2013. |
| Henderson, EB, JL Ohmann, MJ Gregory, HM Roberts, HSJ Zald. 2012. All for one or one for all? Mapping many species individually versus simultaneously with random forest. Ecological Society of America Annual Conference: Portland, OR; August 2012. |
| Ohmann, JL, MJ Gregory, HM Roberts, RE Kennedy, Z Yang, J Braaten, SL Powell, WB Cohen, V Kane, J Lutz. 2012. Mapping change in live and dead forest biomass with Landsat time-series, remeasured plots, and nearest-neighbor imputation. ForestSat 2012: Corvallis, OR; September 2012. |
| Powell, SL, RE Kennedy, JL Ohmann, WB Cohen, MJ Gregory, HM Roberts, V Kane, J Lutz. 2012. Comparison of biomass allometric approaches for regional scale carbon mapping. ForestSat 2012: Corvallis, OR; September 2012. |
| Ohmann, JL, MJ Gregory, HM Roberts, RE Kennedy, WB Cohen, Z Yang, M Moeur. 2011. Spatial monitoring of older forest and habitat for the Northwest Forest Plan. National FIA Users Group Meeting: Sacramento, CA; March 2011. |
| Ohmann, JL, MJ Gregory, HM Roberts, RE Kennedy, Z Yang, M Moeur, WB Cohen. 2011. Landscape context for density management: implications of land ownership and ecological gradients. Conference on state-of-the-art in west-side forest management: Corvallis, OR; October 2011. |
| Gregory, MJ, EB Grossmann, JL Ohmann, HM Roberts. 2010. The Nationwide Forest Imputation Study (NaFIS): Challenges, results and recommendations from the western United States. Forest Inventory and Analysis Science Symposium: Knoxville, TN; October 2010. |
| Ohmann, JL, MJ Gregory, HK May, EB Grossmann. 2010. Nearest neighbor mapping of vegetation gradients for landscape analysis and planning. 53rd International Symposium of the International Association for Vegetation Science: Ensenada, Mexico; April 2010. |
| Ohmann, JL, MJ Gregory, HM Roberts, RE Kennedy, WB Cohen, Z Yang, M Moeur. 2010. Spatial monitoring of late-successional forest habitat over large regions with nearest-neighbor imputation. XXIII International Union of Forest Research Organizations (IUFRO): Seoul, South Korea; August 2010. |
| Grossmann, EB, JL Ohmann, MJ Gregory, HK May. 2009. Gradients or hierarchies? Which assumptions make a better map?. US Regional Association of the International Association of Landscape Ecology Annual Meeting: Snowbird, UT; April 2009. |
| Grossmann, EB, JL Ohmann, MJ Gregory, HK May. 2009. Regional vegetation mapping: Making sense of the methods. Workshop on remote sensing for land managers: Redding, CA; June 2009. |
| Grossmann, EB, JL Ohmann, MJ Gregory, HK May. 2009. Bringing our best data into conservation and restoration planning. California Klamath-Siskiyou Fire Learning Network Workshop: Weaverville, CA; July 2009. |
| Grossmann, EB, JL Ohmann, MJ Gregory, HK May. 2009. Regional vegetation - methods behind the maps: Gradient Nearest Neighbor and random forest modeling. Information Sharing Workshop, Bureau of Land Management: Salem, OR; April 2009. |
| Gregory, MJ, JL Ohmann, EB Grossmann, HK May. 2008. Spatial scaling effects of inventory reference data on nearest neighbor model predictions. Forest Inventory and Analysis Symposium: Park City, UT; October 2008. |
| Gregory, MJ, JL Ohmann, HK May, EB Grossmann, KB Pierce Jr., TM Holt, JS Fried. 2008. Recent advances and applications of nearest neighbors methods for regional-scale forest vegetation modeling. Department of Forest Science Seminar: Corvallis, OR; April 2008. |
| Grossmann, EB, JL Ohmann, J Kagan, KB Pierce Jr., HK May, MJ Gregory. 2008. Random forests and nearest neighbors: Methods for mapping the West Cascades of Oregon. US Regional Association of the International Association of Landscape Ecology Annual Meeting: Madison, WI; April 2008. |
| Grossmann, EB, JL Ohmann, MJ Gregory, HK May. 2008. Is the World a Gradient, or a Hierarchy of Thresholds? Imputing Forest Composition and Structure Variables in the Pacific Northwest. Forest Inventory and Analysis Symposium: Park City, UT; October 2008. |
| Ohmann, JL, M Moeur, M Hemstrom, T Burcsu, J Merzenich, MJ Gregory, HK May, EB Grossmann. 2008. Integrating forest inventory data, vegetation maps, and models of vegetation dynamics to support landscape analysis and planning: the IMAP story. Forest Inventory and Analysis Symposium: Park City, UT; October 2008. |
| Ohmann, JL, MJ Gregory, HK May, EB Grossmann. 2008. Gradient Nearest Neighbor (GNN) maps of forest vegetation: accuracy assessment and uncertainty. Interagency Mapping and Assessment Project (IMAP) Users' Group: Portland, OR; February 2008. | |
| Grossmann, EB, JL Ohmann, J Kagan, KB Pierce Jr., HK May, MJ Gregory. 2007. Models for ecological systems map building: random forest and gradient nearest neighbor. Which one works best?. National GAP Analysis Program Conference: Asheville, NC; September 2007. |
| Ohmann, JL, KB Pierce Jr., EB Grossmann, MJ Gregory, HK May, TM Holt. 2007. Current Vegetation Mapping in Western Oregon. Presented at: USFS Klamath Falls Ranger District: Klamath Falls, OR; June 2007. |
| Ohmann, JL, MJ Gregory, KB Pierce Jr., HK May, EB Grossmann. 2007. Seeing the forest and the trees: harnessing GIS to map forests of the Pacific Northwest. Keynote address to GIS Day: Corvallis, OR; November 2007. |
| Ohmann, JL, KB Pierce Jr., EB Grossmann, MJ Gregory, HK May, TM Holt. 2006. Mapping current vegetation in the Pacific Coast States with GNN, CART, and other tricks. Workshop and field tour with NF, ODF, TNC, and R6: Sycan Marsh Research Station, OR; September 2006. |
| Ohmann, JL, MJ Gregory, KB Pierce Jr., TM Holt, HK May. 2006. Mapping forest species and plant communities with Gradient Nearest Neighbor imputation. 2006 Nearest Neighbors Workshop - Meeting in the Middle: Minneapolis, MN; August 2006. |
| May, HK. 2005. Database development for the Port-Orford-cedar resistance breeding program. Port-Orford-cedar Technical Team Meeting: Hoopa, CA; June 2005. |
Posters
| Ohmann, JL, MJ Gregory, HM Roberts, RE Kennedy, WB Cohen, Z Yang, M Moeur, M Fiorella. 2012. Mapping change of older forest with permanent plots, Landsat time series, and nearest-neighbor imputation. Ecological Society of America Annual Conference: Portland, OR; August 2012. |
| Roberts, HM, JL Ohmann, MJ Gregory, EB Henderson. 2012. Gradient nearest neighbor forest vegetation maps for landscape analysis and planning. ForestSat 2012: Corvallis, OR; September 2012. |
| Zald, HSJ, JL Ohmann, HM Roberts, R McGaughey, MJ Gregory, RE Kennedy. 2012. Influence of inventory plot and Landsat imagery positional accuracies on nearest-neighbor (NN) imputation maps of vegetation composition and structure. ForestSat 2012: Corvallis, OR; September 2012. |
| Gregory, MJ, JL Ohmann, HM Roberts, R Riemann. 2011. Nearest neighbor vegetation maps for landscape analysis and conservation planning: are they good enough, and how will I know?. US Regional Association of the International Association of Landscape Ecology Annual Meeting: Portland, OR; April 2011. |
| Ohmann, JL, MJ Gregory, HM Roberts, RE Kennedy, WB Cohen, Z Yang, M Moeur, M Fiorella. 2011. Spatial monitoring of forest landscape dynamics with permanent plots, Landsat time-series and nearest-neighbor imputation. US Regional Association of the International Association of Landscape Ecology Annual Meeting: Portland, OR; April 2011. |
| Roberts, HM, JL Ohmann, MJ Gregory, EB Henderson. 2011. Gradient nearest neighbor forest vegetation maps for landscape analysis and planning. US Regional Association of the International Association of Landscape Ecology Annual Meeting: Portland, OR; April 2011. |
| Roberts, HM, JL Ohmann, MJ Gregory, EB Grossmann. 2010. Nearest-neighbor forest vegetation maps from FIA plots and geospatial data for landscape analysis and planning in the Pacific Northwest (and beyond). Forest Inventory and Analysis Symposium: Knoxville, TN; October 2010. |
| Grossmann, EB, JL Ohmann, HK May, MJ Gregory. 2009. Mapping mountain hemlock and pinpointing ponderosa pine: Imputation mapping species distributions in Western Oregon. North American Forest Ecology Workshop: Logan, UT; June 2009. |
| Ohmann, JL, MJ Gregory, HK May, EB Grossmann, RE Kennedy, WB Cohen, Z Yang, E Pfaff, M Moeur. 2009. Spatial monitoring of disturbance and late-succesional forest dynamics in the Pacific Northwest. US Regional Association of the International Association of Landscape Ecology Annual Meeting: Snowbird, UT; April 2009. |
| Grossmann, EB, JL Ohmann, J Kagan, MJ Gregory, HK May. 2008. Context-dependent hierarchy of plant community predictors from the Oregon Coast Range to the eastern slopes of the Cascade Mountains. Ecological Society of America Annual Meeting: Milwaukee, WI; August 2008. |
| Ohmann, JL, MJ Gregory, JD Kline, RJ Alig, HK May, EB Grossmann. 2008. Implications of social and ecological gradients for conservation planning in large, multi-ownership, forested landscapes. US Regional Association of the International Association of Landscape Ecology Annual Meeting: Madison, WI; April 2008. |
| Grossmann, EB, JL Ohmann, J Kagan, KB Pierce Jr., HK May, MJ Gregory. 2007. A tale of two techniques: Gradient Nearest Neighbor and random forest for mapping ecological systems in Oregon's Western Cascades. North American Forest Ecology Workshop: Vancouver, BC; June 2007. |