Plant functional types (PFTs) is a system used by climatologists to classify plants according to their physical, phylogenetic and phenological characteristics as part of an overall effort to develop a vegetation model for use in land use studies and climate models. PFTs provide a finer level of modeling than biomes, which represent gross areas such as desert, savannah, deciduous forest. In creating a PFT model, areas as small as 1 km2are modeled by defining the predominant plant type for that area, interpreted from satellite data[1] or other means. For each plant functional type, a number of key parameters are defined, such as  fecundity, competitiveness, resorption (rate at which plant decays and returns nutrients to the soil after death), etc.; the value of each parameter is determined or inferred from observable characteristics such as plant height, leaf area, etc. Climatologists and ecologists struggle to determine which minimal set of plant characteristics best model the actual responses of the biosphere in response to climate changes.any land models classify vegetation by biomes. These biomes set vegetation characteristics such as albedo, roughness length, rooting depth, and stomatal physiology. The use of biomes is reasonable in a top-down modeling approach based on bulk parameterizations of surface energy, water, and momentum fluxes required by atmospheric models.

Please have a look at some of these PDFs..

Thank You, Sir