Habitat heterogeneity and fine-scale environmental gradients are key drivers of plant biodiversity in mosaic landscapes. I examined how small-scale habitat structure and neighbouring land use influence plant communities within meadow plots bordered by forest, shrubland, fallow land, or orchard. Using a nested quadrat design (1 m2, 5 m2, 25 m2), I assessed species richness, Shannon–Wiener diversity, and environmental conditions at multiple spatial scales. Plots adjacent to structurally complex habitats (forest or shrubland) supported higher species diversity (Shannon), whereas species richness increased mainly with quadrat size and showed mixed patterns among plots. Smaller quadrats also captured greater fine-scale variation, particularly in vegetation structure and species turnover, while microclimatic gradients in light and soil moisture strongly influenced diversity patterns. Moist, partially shaded plots supported the highest diversity, whereas open, high-light sites were dominated by a few heliophilous species. Among Ellenberg indicators, soil moisture values showed the strongest positive relationship with diversity, while other factors remained relatively stable; only fertility values declined slightly between years. These findings demonstrate that even in very small patches, subtle within-plot gradients can function as fine-scale analogues of habitat transition zones. Conserving structurally heterogeneous habitats and the fine-scale gradients they generate is crucial for maintaining species-rich and functionally diverse plant communities in fragmented landscapes.