ABSTRACT Litter production in forest ecosystems is a major indicator of primary productivity because litter helps incorporate carbon and nutrients from plants into the soil and is directly involved in plant-soil interactions. To our knowledge, few studies have investigated the relationship between species diversity and ecosystem processes in subtropical forest fragments. In this work, we determined forest structural parameters and assessed seasonal leaf litter input, leaf decomposition rate, litter quality and soil characteristics in two subtropical Atlantic Forest fragments. Litter production was greater in the native fragment with the higher species diversity (FN1). The two native fragments (FN1 and FN2) differed in basal area, volume and dominance in the upper stratum, which were positively correlated with litter production in FN1 but negatively correlated in FN2. Soil in FN1 exhibited higher contents of organic C, available phosphorus and exchangeable calcium, and the leaf litter had a higher C:N ratio. Although these results are consistent with a plant-soil feedback, which suggests the presence of a complementary effect, the dominance of certain families in subtropical forest fragments results in a selection effect on litter productivity and decomposition.