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Soil samples were taken from rhizosphere zone and off-rhizosphere zoneofash (Fraxinus mandshurica Rupr.) and larch (Larix olgensis Henry) in mixed a nd monoculture stands, and the nutrient concentration of N, P, and K was analyze d to study the effect of nutrients variation on yield improvement in the mixed stand. The result showed that: 1) The stand level total soil N concentration and available N in the mixed stand was similar to that in the monoculture stand of ash, but higher than that in monoculture stand of larch. The total N and availabl e N concentration in rhizosphere soil of ash in the mixed stand was similar to t hat in the monoculture stand of ash, but the available N concentration in rhizos phere of larch in mixed stand was much higher than in its monoculture. 2) The stand level total P, total K concentration in the mixed stand was similar to that in monoculture stands of both species, but available P and K was more concentrat ed in the mixed stand than in the monoculture stands of ash. The rhizosphere ava ilable P and K of ash in the mixed stand was 44.1% and 13.5% (for the 9-yr-old s tands) and 79.6% and 25.6% (for the 21-yr-old stands) higher than that in its monoculture. The improvement of soil P and K availability in the mixed stand is concluded.