In GlobCover 2005 and 2009 project, the sensor used for spectral data collection was MEdium Resolution Imaging Spectrometer (MERIS). It observes the Earth in 15 spectral bands in visible and near infra-red region. But I am not getting which of those spectral bands is used for vegetation height detection. Land cover classes in GlobCover consist of vegetation distinguished on the basis of height. But without LIDAR, I do not think that data such as tree or shrub height can be determined. Then how is the vegetation height measured in GlobCover classification?
I'm responding to the comments here which will hopefully sort of answer the question.
I went on an LCCS training course in Rome a few years ago. LCCS is a methodology for creating a legend for your land classification. You build a rule set that says land cover X must have vegetation Y, in semi-arid areas and a periodic brackish water supply, etc etc. You might also state that it's vegetation must be between height X and Y metres.
LiDAR isn't the only way to determine height, LiDAR is relatively new and vegetation heights have been derived for decades from autocorrelation like the techniques used by drone software, also from stereo pairs where more accuracy is required.
So, I would not expect a spectral band in MERIS to be providing height data.