Microwave observations of boreal forests in the NOPEX area of Sweden and a comparison with observations of a temperate plantation in the United Kingdom

The Synthetic Aperture Radar of the University of Denmark's Electromagentics Institute was used to monitor boreal forests at two sites in the Northern hemisphere climate-Processes land-surface Experiment (NOPEX) region of central Sweden. The microwave response of boreal forest was determined as a function of frequency and polarization, and was compared to the behavior of a temperate plantation in the UK. The Swedish stands were also examined by ground measurements. Results showed that, although the Swedish and UK sites were dominated by similar forest species, different relationships were noted between microwave response and biomass density. This was attributed to the fact that the Swedish forests were less intensively managed. The findings showed that the effects of moisture content and surface roughness exerted a considerable influence on the measured relationship between backscatter and biomass density.