Forests/Grass....both use photosynthesis which equates to a low albedo (initially)...read below.
copied from wikipediaBecause forests are generally attributed a low albedo, (as the majority of the ultraviolet and visible spectrum is absorbed through photosynthesis), it has been erroneously assumed that removing forests would lead to cooling on the grounds of increased albedo. Through the evapotranspiration of water, trees discharge excess heat from the forest canopy. This water vapour rises resulting in cloud cover which also has a high albedo, thereby further increasing the net global cooling effect attributable to forests
source:
http://en.wikipedia.org/wiki/Albedo