Trade-offs between soil biodiversity and agricultural expansion : evidence from litter decomposition dynamics in Madagascar Sauvadet, M. /Ba, Seydina Mohamad Razafindrakoto, M. Razafimbelo, T. M. Razafimanantsoa, M. P. Bouvet, J. M. Leong Pock Tsy, J. M. /Trap, Jean Bouillet, J. P. deforestation eucalyptus plantations functional breadth home field advantage litter decomposition slash-and-burn agriculture soil fauna Home-Field Advantage (HFA) theory-positing that litter decomposes faster at its site of origin-allows us to disentangle the respective influences of litter quality, soil biota composition, and microclimate on shifts in litter decomposition following land use conversion. However, HFA remains poorly understood in tropical ecosystems with nutrient-poor soils. We conducted a full in situ litterbag transplant experiment across land use conversion driven by agricultural expansion in Madagascar: secondary natural forests, two stages of slash-and-burn fallows, and Eucalyptus plantations. Litter mass loss, HFA and Functional Breadth (FB)-defined as the capacity of soil biota to decompose different litter types with varying properties at similar rates-was assessed to distinguish the influence of the whole soil food web (coarse mesh) versus micro- and mesofauna-driven processes (fine mesh). These indicators were compared across land uses in relation to soil properties, litter quality, and soil biota composition. Forested land uses had lower microbial alpha-diversity but a higher proportion of specialist taxa than fallows. Natural forests showed markedly higher nematode and macrofauna alpha-diversity, as well as a greater proportion of omnivores and predator taxa, than all the other land uses. Litter decomposition was higher in natural forests, for both litterbag mesh sizes, during the early stage of decomposition, leading to higher FB, but no evidence of HFA effects was observed. Conversely, higher FB in natural forests and positive HFA in Eucalyptus plantations were observed at the late stage of decomposition, but only in coarse-mesh litterbags. This suggests that the decline in ecosystem functioning following forest conversion is linked to the loss of larger-sized macrofauna. Therefore, while Eucalyptus plantations caused less disturbance to microbial communities and early-stage decomposition processes than slash-and-burn fallows, they may not fully replace the multiple ecological roles of native forests, particularly for the functions requiring more specialised organisms and taxa. 2026 text https://www.documentation.ird.fr/hor/fdi:010097459 fdi:010097459 Sauvadet M., Ba Seydina Mohamad, Razafindrakoto M., Razafimbelo T. M., Razafimanantsoa M. P., Bouvet J. M., Leong Pock Tsy J. M., Trap Jean, Bouillet J. P.. Trade-offs between soil biodiversity and agricultural expansion : evidence from litter decomposition dynamics in Madagascar. 2026, [Early Access], [15 p.] EN MADAGASCAR