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Canada Centre for Remote Sensing

Canada Centre for Remote Sensing. Field measurements and remote sensing-derived maps of vegetation around two arctic communities in Nunavut. F. Zhou, W. Chen, B. A. Marriner. Introduction. Objectives

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Canada Centre for Remote Sensing

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  1. Canada Centre for Remote Sensing Field measurements and remote sensing-derived maps of vegetation around two arctic communities in Nunavut F. Zhou, W. Chen, B. A. Marriner

  2. Introduction • Objectives • Quantitatively assess spatial distribution of vegetation around two northern communities using remote sensing technology • Provide vegetation information for • Community planning/development • Impact assessment of climate warming on • Ecosystems • Environment • Wildlife habitat Canada’s Natural Resources – Now and for the Future

  3. Community Locations of the Study Canada’s Natural Resources – Now and for the Future

  4. Field Measurements • Vegetation parameters • Leaf Area Index (LAI) • Cover Percent • Aboveground Biomass (all species) • Total 73 plots at 7 sites measured • 34 plots of 3 sites at Iqaluit • 39 plots of 4 sites at Clyde River • Each plot has a size of 0.5m by 0.5m, separated by 5 meters along a 100 meter transect • Include sparse, medium, and dense vegetation coverage • Remote sensing images used for site selection • Geographic Coordinates Canada’s Natural Resources – Now and for the Future

  5. Harvest Canada’s Natural Resources – Now and for the Future

  6. Vegetation Species • Crowberry • Arctic willow • Net-veined willow • Labrador tea • Blue grass • Mountain Avens • Sedge • Arctic oxytrope • Saxifrage • Arctic white heather • Blueberry • moss • Mountain sorrel • lichen • Pepper grass • Lingonberry • Pepper grass • Forbs Canada’s Natural Resources – Now and for the Future

  7. Sorting Separate species Separate live and dead Separate leave and stems Canada’s Natural Resources – Now and for the Future

  8. Weight (wet and dry) Canada’s Natural Resources – Now and for the Future

  9. Measurement Results Canada’s Natural Resources – Now and for the Future

  10. Images and Processes • Landsat 7 ETM+ • Multiple bands covering from blue to near Infrared • Resolution: 30 by 30 meters • Geometrical correction • Atmospheric correction (6s) • true reflectance from vegetation (+background) • for result comparison of the two communities • Plot coordinates superimposed on the images • Reflectance at the measurement sites extracted from the images for regression analysis Canada’s Natural Resources – Now and for the Future

  11. Regression between RS Images (Reflectance) and Vegetation Parameters • Three groups of linear regression model are experimented • Single band (3, 4 and 5) • Band combination (3 & 4; 4 & 5; and 3, 4 & 5) • Vegetation Index • Normalized Difference Vegetation Index (NDVI) • (b4-b3)/(b4+b3) • Soil Adjusted Vegetation Index (SAVI) • (b4-b3)*(1+L)/(b4+b3+L) • Ratio Vegetation Index -- (RVI) • b4/b3 Canada’s Natural Resources – Now and for the Future

  12. Regression Statistics • Single band vs. Vegetation parameter Canada’s Natural Resources – Now and for the Future

  13. Regression Statistics (cont.) • Band combination vs. Vegetation parameter Canada’s Natural Resources – Now and for the Future

  14. Regression Statistics (cont.) • Vegetation Indices vs. Vegetation parameter Canada’s Natural Resources – Now and for the Future

  15. Regression Statistics (cont.) • Band combination • P-value of the coefficient for Bands 3 and 5, and the intercept is very big. • Band 4 • P-value for variable coefficient and intercept is small intercept (<0.001). • SAVI (Soil Adjusted Vegetation Index) • has the similar magnitude of P-values to those of Band 4. • has an advantage that background soil contribution to image reflectance is reduced. Canada’s Natural Resources – Now and for the Future

  16. Soil Adjusted Vegetation Index ~ Vegetation Parameters Regression Equations Leaf Area Index Aboveground Biomass Cover % Canada’s Natural Resources – Now and for the Future

  17. Vegetation Cover % Map Clyde River Iqaluit Canada’s Natural Resources – Now and for the Future

  18. Aboveground Biomass Map Clyde River Iqaluit Canada’s Natural Resources – Now and for the Future

  19. Vegetation LAI Map Clyde River Iqaluit Canada’s Natural Resources – Now and for the Future

  20. Vegetation Cover Statistics • Clyde River • ~50% of lands -- polar desert • ~30% -- polar semi-desert • Ecosystem with vegetation percent cover > 50% only accounts for ~1.5% of the lands • Iqaluit • ~30% of lands -- polar deserts • ~30% -- polar semi-deserts • Ecosystem with vegetation percent cover > 50% accounts for about 5% of the landmass Canada’s Natural Resources – Now and for the Future

  21. Discussion • Relative sample errors of measurements reduce with increases in plot number and vegetation coverage. • For the two communities, SAVI has a good correlation coefficient with the measured vegetation parameters. • Vegetation in Arctic varies locally and regionally. Remote sensing is an efficient tool to investigate the spatial distribution and temporal variation of the vegetation in Arctic region. It usually could produce more accurate results. • The vegetation maps around the two communities are derived from the field measurements at 7 sites and RS images. More field measurements may be required to improve the accuracy of the results. Canada’s Natural Resources – Now and for the Future

  22. The team in the field … Thank you Canada’s Natural Resources – Now and for the Future

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