Coffee forests are the most valuable land-use systems that provide multiple benefits such as biodiversity conservation, carbon sequestration and source of income. This study aimed to estimate the carbon stock of coffee agroforestry systems and the contribution of coffee plants (Coffea arabica L.) to carbon sequestration in the entire coffee agroforestry systems in southwestern Ethiopia. The carbon stock in trees was estimated by field-based measurements and allometric equations, whereas the carbon stocks in litter and soil were determined using field sampling and laboratory analysis. The carbon stocks of the coffee agroforestry systems in the study site ranged from 254.9 t C/ha in the Syzygium-shaded coffee forest to 321.8 t C/ha in the Albizia-shaded coffee forest. The overall mean carbon sequestration in the present coffee agroforestry systems was 287.1 t C/ha. The net carbon sequestered by coffee plants in the agroforestry systems ranged from 18.8 t C/ha in the Syzygium-shaded coffee stratum to 48.5 t C/ha in the Albizia-shaded coffee stratum. This demonstrates that Albizia is the most compatible shade tree for coffee plants. On average, coffee plants contributed 37.5 t C/ha, accounting for approximately 12.8% of the total carbon sequestered in the coffee agroforestry systems. Hence, we recommend coffee forests for all-in-one benefits such as climate change mitigation, sustainable landscape management and income generation.

Wood density and wood chemical traits are strong predictors of tree performance, carbon stock, and wood decomposition, which play important roles in ecosystem processes and carbon and nutrient cycling in forests. However, it remains unknown how root wood traits are related to stem wood traits. We examined the relationships of wood density and wood chemical traits (lignin and nitrogen concentrations, carbon-to-nitrogen ratio) between the stems and coarse roots of 90 individuals representing 53 tropical tree species in Malaysian Borneo. We developed regression equations of each wood trait using the standardized major axis method. Each root wood trait was highly correlated with the corresponding stem wood trait, and most regression equations fitted well (R2 > 0.5). The lignin concentration of roots was significantly greater than that of stems. We conclude that root wood traits can be estimated from the corresponding stem wood traits in South-East Asian tropical trees. Further analysis of coarse root decomposability will provide more accurate estimates of carbon and nutrient fluxes in tropical forest ecosystems.

Conversion of forest to other land uses is a major contributor to climate change. The coastal forests of Tanzania have increasingly been recognized as being of global biodiversity importance, due to high rates of species endemism. Rates of forest loss are similar to those of other tropical regions, resulting in increasing levels of threat for the biological values within the remaining forest and potentially significant source of CO2 emissions. This study estimated the remaining cover and carbon stock of Tanzania's coastal forests and the CO2 emissions due to forest loss between c. 1990 and c. 2007. Coastal Tanzania contained over 273 700 ha of forest in 2007. Deforestation rates in the area have slowed from 1.0% yr−1, or > 3735 ha yr−1 during the 1990s, to 0.4% yr−1, or > 1233 ha yr−1 during 2000–2007. Despite lower deforestation rates in 2000–2007, the percentage forest lost from within reserved areas has remained steady at 0.2% yr−1 for both time periods. CO2 emissions from deforestation slowed from at least 0.63 Mt CO2 yr−1 in 1990–2000 to at least 0.20 Mt CO2 yr−1 in 2000–2007. Regional forest clearance in Tanzania is highly dynamic; while rates have slowed since 2000, forest habitat conversion has continued and there is no guarantee that future rates will remain low. A rigorous policy on reducing emissions from deforestation and degradation (REDD) should be implemented to avoid future increases in deforestation rates.