Inventory of Agroforestry systems in the highland regions of Kerala, India

Abstract

Agroforestry systems (AFS) play a vital role in tropical regions, integrating diverse tree species with field crops to support sustainable agriculture and biodiversity conservation. Despite their significance, comprehensive assessments of AFS, particularly in regions like the Western Ghats, remain limited. This study investigates the agroforestry systems in the Kerala region of the Western Ghats, a biodiversity hotspot focusing on species composition and abundance patterns across different crop-based systems particularly above 600 meters (msl). Field sampling was conducted by direct on-ground observations, to determine the crop and tree compositions in each AFS. The study enumerated 119 tree species within 116 sample plots, categorized into five main AFS types: coffee-based, cardamom-based, rubber-based, tea-based, and homegarden-based. The species were represented in various functional groups including timber, medicinal, fuelwood, food crops, fodder crops, ornamentals and other MPTs. The functional diversity has been computed for the prominent agroforestry systems under study. The most dominant functional group among all the systems was timber species followed by medicinal plants and food crops. The study revealed the consistent prominence of Artocarpus heterophyllus across various agroforestry systems with 187 trees/ha in coffee based, 360 trees/ha in cardamom based, and 327 trees/ha in homegarden based systems. In rubber-based systems, Hevea brasiliensis dominated with 917 trees/ha, while Grevillea robusta took the lead in tea-based systems with 550 trees/ha. Considerable variation was observed in species composition among the agroforestry systems which indicate the distinctiveness of each system. Average standing stock per hectare of prominent timber species for the entire AFSs studied ranged from Grevillea robusta (50.33 m³/ha) to Erythrina variegata (5.08 m³/ha).  The study underscores the importance of understanding AFS for their sustainable management and biodiversity conservation, especially in climate vulnerable ecoregions like the Western Ghats. It also highlights the need for continued research and conservation initiatives to safeguard the unique biodiversity and cultural heritage of these landscapes.