Effects of forest cover, temperature and flower abundance on cashew pollinators in the northern Western Ghats, India

Abstract

Global declines in pollinators pose serious risks for biodiversity, ecosystem functioning, and human well-being. Understanding how landscape structure and climate shape pollinator communities is critical, yet studies that jointly assess these factors in human-dominated tropical landscapes remain scarce. Here, we investigate how forest cover, distance to forest patches, flower abundance, and temperature influence pollinator communities in monoculture cashew plantations that are rapidly expanding in the northern Western Ghats, part of the Western Ghats-Sri Lanka global biodiversity hotspot. We conducted 210 half-hour observation sessions across 30 cashew orchards in Dodamarg, India. At the community level, flower abundance and forest cover positively influenced pollinator richness, number of pollinators, and number of visits. The number of visits showed a unimodal response to temperature, with peaks occurring within narrow, taxon-specific ranges, lower temperatures for birds and higher for insects, likely reflecting physiological constraints. At the species level, flower abundance and temperature emerged as key predictors of occurrence, while three butterfly species occurred more frequently near forest patches. Contrary to expectations, proximity to forest did not reduce ambient orchard temperatures, suggesting limited forest-mediated thermal buffering in our site. Together, these findings highlight the vulnerability of pollination services to both land-use change and rising temperatures. Ongoing conversion of natural forests to cashew monocultures, coupled with climate warming, may erode pollinator communities and jeopardize crop yields in tropical agroecosystems. More broadly, our results underscore the importance of conserving remnant forests and accounting for thermal sensitivity of pollinators to sustain ecosystem services in changing landscapes worldwide.