The transition from shifting cultivation to indigenous agroforestry as nature-based solution for land restoration in the Indian Eastern Himalayas

Abstract

In the Indian Eastern Himalayas, shifting cultivation has long been a major cause of land degradation. However, indigenous communities, like the Hmar, have successfully transitioned from shifting cultivation to agroforestry systems such as pineapple agroforestry, leading to land restoration and increased household incomes. Despite these positive outcomes, little is known about how soil health indicators change during this transition. Thus, the present study aimed to investigate changes in selected soil health indicators and erodibility across different age classes of pineapple agroforestry systems (<5, 5–10, 11–15, and > 15 years old) compared to shifting cultivation and nearby natural forests. Soil samples were collected from six sites, including different stages of pineapple agroforestry systems, shifting cultivation phases, and a natural forest. At each site, three (10 × 10 m) quadrats were selected, and two (1 × 1 × 1 m) vertical soil pits were dug in each quadrat, sampling soil depths from 0 to 100 cm. The transition from shifting cultivation to pineapple agroforestry improved soil organic carbon (SOC) and stratification ratios while reducing soil erodibility. SOC stocks were estimated at 182.7 Mg C/ha for natural forest land and 188.2 Mg C/ha for the cropping phase in shifting cultivation. On the other hand, estimated SOC stocks for < 5, 5–10, 11–15 and > 15 years old stands of pineapple agroforestry system were 169.7 Mg C/ha, 157.2 Mg C/ha, 168.9 Mg C/ha and 177 Mg C/ha respectively. Thus, the estimated SOC stocks under > 15 years of pineapple agroforestry were comparable with adjacent natural forest land. The stratification ratios (SR > 2) for SOC and macronutrients indicated better soil quality in the pineapple agroforestry system than in the cropped land. The clay and modified clay ratios decreased with increasing age of pineapple agroforestry system stands. The highest clay ratio was recorded in the topsoil of < 5-year-old pineapple agroforestry system, indicating a greater risk of exposure to rainfall events than in natural forest land and the cropping phase in the shifting cultivation cycle. It is concluded that transitioning from shifting cultivation to a pineapple agroforestry is a nature-based solution to restore degraded lands and presents an excellent opportunity for sustainable soil health and carbon sink management.