Recent work by Pearson et al. [24] focused on the perceived key cause of forest degradation: timber harvest and associated infrastructure (skid trails and logging roads).
Common drivers of forest degradation include timber harvesting (legal and illegal), fuel wood collection, non-stand replacing fires, and animal grazing in the forest (preventing forest regeneration) [11].
Marchak's description ("Forest Degradation, the Timber Trade, and Tropical-Region Plantations") provides a particularly sobering case of how market-driven initiatives especially those with a global reach have resulted in widespread degradation and the loss of tropical timber species.
Table 5 Proportion of total forest degradation emissions by degrading activity by region Timber Woodfuel Fire America 69 10 21 Africa 31 36 33 Asia 61 35 5.
In the JGP (85,200 ha) we identified four major drivers of deforestation and forest degradation, including unsustainable timber and fuel wood extraction, agriculture and pasture expansion, each responsible for 21%, 28%, 37% and 14% of the total historical deforestation respectively over the past 10 years, equivalent to 14,163 ha (1.8 % annual deforestation rate).
In our modelling of unsustainable timber production for the JGP, which has led to deforestation and forest degradation over the past 10 years, we estimated that the forest is used for timber extraction over a period of seven years with an available extraction volume of 5.9 m³/year and a commercial recovery rate of 30%, sold at an average of US$ 112.5/m³ at the farm-gate.
Thus the findings of Hosonuma et al. are largely in agreement with the findings of this study (Table 5) and highlight that the harvesting of timber and woodfuel are the largest contributor of emissions associated with forest degradation.
Fig. 3 Spatial distribution of forest degradation emissions and percent of total forest emissions for: a, b total degradation emission by region within countries, c, d timber extraction emissions (only national level), e, f woodfuel emissions, and g, h fire emissions.
Table 4 Estimated annual emissions from deforestation and forest degradation and relative proportions Activity Annual emission (Gt CO2e year−1) % Degradation 2.06 25 Timber 1.09 53 Woodfuel 0.62 30 Fire 0.35 17 Deforestation 6.22 75.
We estimated total forest degradation emissions of 2.1 Gt CO2e year−1, of which 53% was derived from timber harvest, 30% from woodfuel harvest, and 17% from forest fires.
