Darren Pouliot et al. – Trends in vegetation NDVI from 1 km AVHRR data over Canada for the period 1985-2006.

Vegetation is known to be sensitive to changes in climate. Drought in the Prairie regions of Canada is one example. Local changes in climate such as temperature and precipitation can alter vegetation productivity in the short term (e.g. 1-5 years). Over longer periods (> 10 years) consistent changes in climate can alter vegetation density and species composition. In northern regions field and remote sensing observations have identified that vegetation is undergoing both short and long term changes.

New research by Darren Pouliot and others looks at the Normalized Difference Vegetation Index (NDVI) for the entire country, for the time period 1985-2006. Using 1km data captured by the Advanced Very High Resolution Radiometer, temporal trends in vegetation NDVI have been mapped. NDVI is known to increase as the amount of healthy green vegetation increases, and has a strong linear relationship to a wavelength of solar radiation absorbed during photosynthesis, and as such is an excellent representation of gross photosynthesis (GPP) in a vegetation canopy. By comparing images, it is possible to determine the difference in vegetation within the same area and infer whether a positive or negative change has taken place.

By applying trend analysis to the processed 1km AVHRR data records, a positive trend in NDVI was discovered for some northern areas. This supports the phenomenon of northern “greening” identified in other studies, but the trend did not apply to all parts of the country. Most areas in southern Canada showed little significant change, and what was discovered was largely related to land use or land cover changes, not changes resulting from climate. It is unknown what impact a “greening” northern landscape will have on the people, plants, animals, hydrology or climate of these areas.

For more information contact Darren Pouliot or ERCC@nrcan.gc.ca

References
Long term changes in vegetation from 1KM AVHRR NDVI data over Canada for the period 1985-2006; Pouliot, D A; Latifovic, R; Olthof, I. International Journal of Remote Sensing. (ESS Cont.# 20070270 In Press).

Useful Link
Earth Science for National Scale Characterization of Climate Change Impacts on Canada's Landmass