The transitions between PFTs were calculated as follows. Firstly,
the land cover maps between different years were compared in
order to find the classes that changed between epochs. Only 15
land cover classes were involved in the pixels that changed (the
classes with stars in Table S1). The possible transitions among these
15 land cover classes were then calculated. In order to reduce the
computing load and time, transitions with an area of less than 0.5%
of the global total transition area were ignored. Consequently, the
total coverage of global transitions was 95% from 2000 to 2005 and
92% from 2005 to 2010, respectively. The transitions in the original land cover classes of the CCI maps were then translated to the
transitions in the 14 PFTs using the conversion factor table (Table
S1).