Fig. 1. LUC processes and associated carbon fluxes.

LUC processes considered in this study are: conversion of intact land (exemplified as intact forest (a)) into agricultural land (c), forest wood harvest for fuel wood (d), and industrial wood (e), and regeneration of secondary forest following harvest or agricultural abandonment (f). An old forest was used as an example for intact land in this figure, but similar land transitions involving natural grassland were also included. Likewise, pasture was also included as a form of agricultural land. The individual carbon fluxes comprising E_LUC are: b, d E_fire, immediate emissions following forest clearing through burning of aboveground biomass and other on-site disturbance, plus emissions from harvested fuel wood assumed to be burned at the year of harvest; e E_legacy, emissions from recently established agricultural land that is dominated by the decomposition of legacy slash and soil carbon inherited from former intact land; b E_wood, long-term, gradual carbon release from industrial wood product degradation; and f S_recov, carbon sink in recovering secondary forest and grassland. The net land-use change emissions (E_LUC) is defined as: E_LUC = E_fire + E_wood + E_legacy − S_recov, with a positive sign indicating a carbon source to the atmosphere. The dashed arrows indicate conversion of secondary forest (or grassland) into agricultural land in shifting cultivation, or reharvest of wood in case of forest management.