Agroforestry offers multiple ecosystem services in degraded lateritic soils

Abstract

Degradation of agricultural and forest lands is a global problem causing climate change, loss of biodiversity, ecosystem services, and environmental hazards. In the red and lateritic soils of the northeast, central and southern India, land degradation remains a major problem affecting the lives of millions of people. Agroforestry systems with appropriate combinations of arable crops, horticultural trees, and forest tree species are suggested as effective strategies to combat land degradation by restoring biodiversity and ecosystem services but the scientific evidence is lacking for red and lateritic soils of northeast India. In response, a forest deciduous tree species Gmelina [ Gmelina arborea Roxb.], a fruit tree mango [ Mangifera indica L.], and a legume crop pigeon pea [ Cajanus cajan (L.) Millsp.] were grown solely or in various combinations for ten years (July 2009 to June 2019) in the red and lateritic soil of West Bengal, India to evaluate their role in the restoration of degraded land and the potential for offering multiple ecosystems services. Eleven indicators were selected for evaluating the multifunctionality of ecosystem services having synergies between them. Results after ten years of field experiments revealed that the Gmelina -mango-pigeon pea agroforestry system has provided multiple ecosystem goods like edible seeds (pigeon pea), fruits (mango), fuelwood and timber (mango/ Gmelina ) sequentially, and was 2–3 times more profitable in terms of net present value compared to sole Gmelina or mango or pigeon pea. This system also offered greater climate resiliency with 1–2 times higher annual biomass production , thus offsetting greenhouse gases emission . The composite evaluation index demonstrated that this system offers the highest level of multifunctionality of multiple ecosystem services. Evidence from this long-term experimentation suggests that the crop-fruit tree-forest tree-based agroforestry system has the potential to restore the land productivity of the degraded red and lateritic soils and provide multiple ecosystem services to millions of people dependent on such land. This system could potentially be out-scaled in many other similar agroecological zones of the world. • A new comprehensive evaluation index of ecosystem services is proposed. • Agriculture, horticulture, forestry and agroforestry were compared with the new index. • Agroforestry shows the highest level of synergies of multiple ecosystem services. • It results in net positive C balance, high EROI, and improved biodiversity.