Effects of forest plantations on soil carbon sequestration and farmers’ livelihoods

The establishment of monoculture forest plantations with exotic, fast-growing species is common in tropical countries. This study was conducted to determine both (1) the long-term effects of plantations on soil organic carbon (SOC) and (2) the social impact of the plantation on farmers’ livelihoods in Ethiopia. Tree plantations of Cupressus lusitanica and Eucalyptus saligna were established on abandoned mechanized farmland nearly 30 years ago. SOC amounts under forest plantations were compared with SOC of mechanized farmland, traditional farmland and natural forest which was the reference site. The study had a retrospective design and differences in SOC contents were compared between the five land uses sampled at two different occasions with a 10-year interval. Moreover, 20 farmers in total, both male and female, living at different distances from the plantations, were interviewed in order to assess the difference in the social impact of the plantations on farmers’ livelihoods. The results showed that the amount of SOC sequestered under the five land uses in the 0-20 cm soil layer differed significantly and was highest under C. lusitanica followed by E. saligna, natural forest, and traditional and mechanized farmland. However, the forest plantations do not yet seem to be in a steady-state with respect to SOC. Due to the establishment of plantations, farmers’ livelihoods have changed in different aspects. The impact of the plantations was stronger in households situated closer to the plantations than for those people who lived further away from the plantation area. Those farmers who lived near the plantations had easier access to collect firewood and graze their livestock. They had also more job opportunities and access to shelter and were inspired to start on-farm Eucalyptus plantings. On the other hand, they also had to face problems associated with the plantations such as loss of agricultural land due to the establishment of plantations, crop destruction by wildlife, and conflicts with the forest guards