Post-landslide restoration through multistrata agroforestry-based land management in the West Bogor area of Indonesia

Abstract

The West Bogor area experienced a landslide disaster, causing extensive damage to secondary forest areas, plantations, and residential homes. Despite evacuations, the community persists in using the affected land for agriculture. This study aims to develop a land management model based on agroforestry for post-landslide restoration, to prevent landslide reactivation, and to provide benefits for the local community. Introducing an agroforestry system that includes deep-rooted trees and perennial crops on landslide-prone slopes can improve slope stability by enhancing soil structure and water retention, minimising erosion and landslides. The study examines unexplored aspects of landslide characteristics and zoning as a novel approach to improve mitigation strategies. We classify the post-landslides area into depletion, transition, and accumulation zones. The lithology comprises Breccia with pumice and Andesite gravels, a sandy tuff matrix, and Claystone underneath, acting as the slip surface. The northern landslide has depletion, transition, and accumulation zones ranging from 743 to 710 m above sea level (masl), 710 to 694 masl, and 694 to 676 masl. In the southern landslide, these zones range from 783 to 720 masl, 720 to 705 masl, and 705 to 676 masl. Based on the characteristics of those zones, we develop an agroforestry model in a vertical pattern with species strata, fast-growing local plants, strong and deep roots, and a relatively high evapotranspiration rate. The depletion zone is managed as a complex agroforestry system (forest type) consisting primarily of forest plants and plantation crops. The transition zone is a complex agroforestry (garden type) with plantation crops and some forest plants. The accumulation zone is a simple agroforestry system with seasonal crops. On almost flat land in an accumulation zone suitable for Oryza sativa cultivation, we apply Cocos nucifera as a protective plant. Soil fertility in all zones is improved with organic and inorganic fertilization, and it also increases the mycorrhizal population through the planting of leguminous plants. The multistrata agroforestry model, created and adapted to the specific characteristics and zoning of landslide-prone areas, is expected to significantly enhance landslide restoration and erosion mitigation and reduce the risk of future landslides. Such approaches can be extended to regions with comparable characteristics.