Monitoring Natural Vegetation in Southern Greenland Using NOAA AVHRR and Field Measurements

Abstract

The application of the Normalized Difference Vegetation Index (NDVI) for monitoring natural vegetation and biomass production has been evaluated for a sheep farming area in southern Greenland. Field measurements of spectral reflectance data during the growing season have been used to make a calibration between NOAA AVHRR NDVIs and aboveground vegetation quantities. The potential biomass production is estimated as the product of mean NDVI and the length of the growing season. Lowest-order atmospheric as well as geometric corrections were carried out on the satellite data before the seasonal and regional variations were correlated with climate and water balance. Agriculture in southern Greenland started when Eric the Red came from Iceland around 982 A.D., and the Norse era ended approximately 500 years later because of climatic change, extensive overgrazing and soil erosion. Modern sheep farming started in 1924, but the threats to sheep breeding and the environment are the same today as during the Norse era. The satellite-based monitoring has proved to be a useful tool to avoid overgrazing, which in this foehn-affected area easily implies soil erosion. It is a quick and low-cost method, and in combination with meteorological and soil water data it is possible to forecast the dry biomass production at the beginning of each growing season. This facilitates agricultural management and planning of the potential breeding capacity in this vulnerable marginal environment.

Key words: southern Greenland, NOAA-AVHRR, Normalized Difference Vegetation Index, atmospheric corrections, biomass production