The early studies of the ASB Partnership for the Tropical Forest Margins stratified the domain for study into stages of a generic transition pathway that suggested a strongly non-linear trajectory of change. In this scheme, a phase of degradation of above-ground vegetation, based on over-logging or shortening fallow cycles in intensified swiddens can lead to a grass-fire cycle that needs special conditions to allow successful rehabilitation. Many places with current agroforestry and tree mosaics have gone through such a phase. A new review of the global literature on these ‘forest transitions’ by Meyfroidt and Lambin (2011) framed important conclusions.
Land use trajectories that avoid a low tree-cover phase and ‘bypass’ the high emission stages are often targeted in REDD+ policies; examples exist in transitions of swiddens to agroforests rather than intensive annual cropping systems degrading into grasslands with frequent fire. Changes in land tenure regime are often key to change in tree cover.