Chapter 5 - Viable land use options to achieve multiple ecosystem services in the Eastern Himalayas of India

Abstract

Avoiding forest conversion to other land uses provides the best ecosystem integrity and functioning; however, other important ecosystem services such as food production and other livelihood needs must be considered. The target is therefore to maintain adequate soil organic carbon (SOC) stocks to mitigate the effects of climate change. Sustainable soil management allows for achieving several Sustainable Development Goals (SDGs). Specifically, SOC sequestration targets are addressed by “Climate action” and “Life on Land.” Shifting cultivation, locally named jhum, is a major land use in the Eastern Himalayas region of India, based on crops or crop mixtures for household consumption, following forest clearing and burning. Thereafter, jhum fields are abandoned and naturally regenerate into a secondary forest. However, jhum cultivation decreases the forest area, while erosion increases as a consequence loss of soil and nutritive elements. A total of 204 sites were sampled in Nagaland state and categorized according to land use, vegetation type, and final use. SOC stocks were higher in primary and secondary forests (29.8MgCha−1), followed by plantations (28.7MgCha−1) and jhum (25.5MgCha−1) land use. Considering vegetation type, SOC stocks were greatest in alder forests (31.7MgCha−1), tea gardens (36.6MgCha−1) among plantations and rice+maize (30.6MgCha−1) among jhum. The lowest values were found in secondary forests (26.7MgCha−1), Melia dubia (23.6MgCha−1) and mixed jhum crops (15.1MgCha−1). Considering final use, SOC stocks were the highest in cash crops (33.1MgCha−1) and the lowest in food crops (25.0MgCha−1) in jhum. Increase in SOC compared to the mixed forest land use was 18.3% in tea plantations, 2.4% in alder forests, and 0.4%–0.6% in bamboo and mixed timber trees plantations. The highest decreases corresponded to the jhum land uses, ranging from 1.2% to 51.2% (rice+maize and mixed jhum, respectively). Compared with the jhum land use, SOC increase was the highest in tea plantations (43.8%), followed by alder forests (24.4%), mixed timber trees (22.2%), and bamboo (21.9%). The lowest increases were found in Duabanga grandiflora (3.0%) and Gmelina arborea (1.9%) plantations for timber production.