NDVI variation and its relation to climate in Canadian ecozones |
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Authors: | Yuhong He Xulin Guo Paul Dixon John F Wilmshurst |
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Institution: | 1. Department of Geography, University of Toronto Mississauga;2. Department of Geography and Planning, University of Saskatchewan;3. Western and Northern Service Centre, Parks Canada;4. Jasper National Park of Canada |
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Abstract: | Parks Canada began the Northern Satellite Monitoring Program in 1997, with the objective of tracking large‐scale vegetation variation in Canadian ecosystems and helping land managers to develop appropriate management practices in response to climate change. Under this program, a sequence of 10‐day composite Advanced Very High Resolution Radiometer (AVHRR)‐derived Normalized Difference Vegetation Index (NDVI) data from 1985 to 2007 was examined to study seasonal and inter‐annual relationships between vegetation and climate data over Canadian ecosystems using statistical and wavelet analysis. Statistical analysis showed that temperature was the principal driver for seasonal variability in greenness, explaining more than 70 percent of seasonal variation in vegetation for most Canadian ecozones. In comparison with temperature, the relationships between NDVI and precipitation were weaker but still significant. Maximum annual NDVI showed increasing trends in Canadian ecozones during the study period, although increasing rates were spatially heterogeneous. Wavelet analysis confirmed that inter‐annual variation in NDVI was different at two ecozones in Canada. NDVI variation in the Northern Arctic was significant at scales of 3–4 years from 1997 to 2001, which was associated with temperature and precipitation variation. Comparatively, NDVI variation in the Boreal Shield was significant at scales of 5–8 years from 1991 to 1999, but did not correspond with climate variation. |
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Keywords: | vegetation variation AVHRR NDVI climate conditions seasonal and inter‐annual relationships wavelet analysis variation de la vé gé tation Radiomè tre perfectionné à trè s haute ré solution Indice de vé gé tation par diffé rence normalisé e conditions climatiques relations saisonniè res et interannuelles analyse par ondelettes |
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