|Title||Télédétection de la dynamique et de la productiité de la forêt boréale à partir de l'indice de végétation global AVHRR-NOAA|
|Author||Goita, K; Royer, A; Beaudu, F; Cihlar, J|
|Source||17th Canadian Symposium on Remote Sensing, Proceedings, Saskatoon, Saskatchewan, June 13-15; 1995 p. 67|
|Alt Series||Earth Sciences Sector, Contribution Series 20042597|
|Abstract||The boreal forest that circles the entire northern hemisphere is a major ecosystem that may be making a significant contribution to biogeochemical cycles and water and energy exchanges. Specifically,
its role in absorption of atmospheric CO2 is at the heart of current concerns about changes in the global environment. Characterization of interannual forest dynamics will lead to a better understanding of biosphere-climate interactions
associated with phenomena caused by the biological activity of the ecosystem.|
This article presents the results of an analysis of weekly variations in the Global Vegetation Index (GVI) identified from synthetic images from the NOAA AVHRR
sensor over the period from 1985 to 1992. The data were corrected for radiometric (sensor calibration drift) and atmospheric effects. A filtering model was then applied to the corrected GVI data to attenuate residual directional effects. The study
covered all of Quebec and various forested areas of Alaska, Finland and Siberia.
GVI data were used to quantify certain parameters that characterize boreal forest dynamics, e.g., the period, duration and intensity of photosynthetic activity of
the tree cover during the growing season. Significant relationships were established between these parameters and the climate factors that govern net primary productivity (NPP): air temperature (growing degree-days), surface temperature estimated
from AVHRR thermal channels, precipitation and photosynthetically active radiation (PAR). The marked differences observed among the areas studied emphasize the importance of an improved analysis of the functioning of boreal forests, at a high level
of spatial resolution. Finally, various possibilities for the development of a model to estimate and monitor NPP by global-scale remote sensing are discussed.
The availability of synthetic imagery such as that provided by NOAA AVHRR
satellites, which covers the entire planet on a weekly basis, opens up new prospects for the study of ecosystem dynamics.