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This study examined a pair of neighbouring small watersheds with similar topographical and geological backgrounds.Since 1954, natural revegetation has been conducted in one of these watersheds, and artificial afforestation has been conducted in the other.The two watersheds have formed completely different landscapes: naturally restored grassland and artificial forestland.The differences in soil total N, soil nitrate (NO3-) and ammonium (NH4 +) N and soil δ15N in the upper 1 m of soils were investigated in the two ecosystems.Additionally,δ15N was measured in tree rings in the forestland and used as a proxy for soil N availability.