The qualified prevalence of natural and planted tropical reforestation

AbstractRecent satellite estimates suggest that planted tree cover rivals, and possibly exceeds, the area of natural reforestation pantropically, challenging longstanding models of forest change. Such estimates underscore a tension between studies of reforestation as an areal expansion of undifferentiated forest cover versus dynamic land-change processes by which forest variously emerges in transformed states. A review of land-change processes bearing on the nature of reforestation would qualify the relative prevalence of planted tree cover, but with caveats. Planted tree cover would be less than half the nominal extent of natural reforestation if including the 29-61% of natural reforestation re-cleared within 15 years and excluding the 25-50% of planted tree-cover entailing extant forest conversion. Planted tree cover would however be comparable to natural reforestation if also discounting the 31-52% of natural reforestation that similarly follows from forest conversion. Satellite-based estimations of reforestation area may now, and should, incorporate such qualifying land-change processes by borrowing from demographic models of population change and including ‘spurious’ reforestation integral to the broader processes of reforestation of interest.