Agricultural inputs unevenly boost crop yields but consistently reduce biodiversity on Mount Kilimanjaro

Agricultural systems depend on Nature's Contributions to People (NCP), but their management often diminishes biodiversity, potentially undermining their sustainability. Thus, understanding the relationships between biodiversity, human capital (labour and physical inputs) and crop yields is essential for sustainable management, particularly in biodiverse ecosystems.

We investigated the relationships between biodiversity, human capital and crop productivity across 15 long‐term monitoring plots spanning three cropping systems (coffee, banana and intercropped maize and beans) on the southern slopes of Mount Kilimanjaro, Tanzania.

Using ecological surveys, semi‐structured farmer interviews and detailed yield assessments, we quantified crop yield (both mass and economic value), human capital and a multidiversity index (MDI) encompassing the species richness of birds, bats, bees, dung beetles and trees. Structural equation models were used to estimate the direct and indirect effects of climate, biodiversity and human capital on yield value.

Labour capital was strongly and positively associated with crop yield value. Meanwhile, physical capital, which included costs for agrochemicals such as fertilizers and pesticides, was negatively associated with the MDI but showed no positive association with yield value. Biodiversity, as measured by the MDI, was not significantly associated with yield value, which may reflect low statistical power, a dominant role of agricultural inputs in driving yields or weak ecological contributions. Among cropping systems, intercropped maize and beans exhibited the highest MDI, while coffee plantations showed the lowest.

Practical implications . These findings suggest that reducing agrochemical dependence could offer opportunities to enhance biodiversity without necessarily compromising productivity, though uncertainty remains. Nevertheless, in line with global calls for sustainable, biodiversity‐friendly agriculture and other regional research, we recommend policy and economic incentives for low‐input systems, the integration of agroecological practices and the use of precision input management. Overall, our results highlight the potential for ‘win‐win’ strategies that balance agricultural productivity, biodiversity and rural livelihoods on Mount Kilimanjaro.