Plant cover also increases evaporation (because the water get trapped by the plants on the surface), which increases warming (because water vapour is a very pow

Plant cover also increases evaporation (because the water get trapped by the plants on the surface), which increases warming (because water vapour is a very powerful greenhouse gas), but also reduces local temperatures (evaporation removes heat), and increases cloud cover (which reduces warming by increasing albedo). It's a very complex system, and working out the net effect is very difficult (as the paper says).