Logging residues and CO2 of Brazilian Amazon timber: Two case studies of forest harvesting

Forest management has been repeatedly mentioned as a strategy to reduce damage caused by logging when compared with conventional logging. Much has been learned about logging impacts and prospects for forest management, but there are still too many gaps regarding the CO2 emissions in logging, due to residues and their impact on the carbon balance. Here we compare CO2 emissions between two timber harvesting intensity systems. Logging with an intensity of 30 m3 ha−1 (L30) and logging with an intensity of 15 m3 ha−1 (L15) were compared over 4 rotation periods (120 year total timeframe). Original logging residues (LR) data was used to determine emissions from residues decomposition. On average, L30 has produced more LR (41.60 t ha−1), than L15 (20.90 t ha−1); for each tonne of commercial stem in L30, 2.13 tonnes of logging residues were obtained and 2.05 tonnes of residues were found in L15. Moreover, we have created a scenario representing the carbon balance (emissions from residues versus carbon uptake from biomass re-growth) over a 120 year long period to evaluate the outcomes for both logging intensities. We find that it will need about 38.3 years under L30; whereas 18.2 years were required in the case of L15. The L30 growth period is greater than the cutting cycle, which means that aboveground standing biomass is not able to fully recover until the next cutting cycle. Fully biomass recovery was only achieved when L15 was applied. Furthermore, the diameter of the commercial tree species takes a longer time to recover than the cutting cycle. Finally, ignoring the post harvesting life cycle phases, both CO2 balances were negative, which means that both practices ended up uptaking CO2 from the atmosphere.