[Objective] This study investigated the differences and dynamic relationships among multiple ecosystem services by considering the trade-off relationship of a Robinia pseudoacacia plantation with different ages and slope aspects. The findings will provide a theoretical basis for the scientific management of R. pseudoacacia plantations in the residual gully region of the Loess Plateau.[Methods] We set up 36 plots according to different stages of forest age and different slope aspects. The water conservation

soil carbon storage

soil nitrogen storage

annual productivity

and biodiversity of the selected stands were measured. Statistical parameters including the root mean square deviation were used to determine their trade-off relationship

and a redundancy analysis was performed to determine the correlation between ecosystem services and stand factors.[Results] ① The ecosystem services of the R. pseudoacacia plantation at the various ages and slope aspects were significantly different (p<0.05). As the forest age increased

so did the benefits of water conservation. Annual productivity initially increased but then decreased from young forests to middle-age forests

and was the greatest for the middle-age forests. Biodiversity increased at first and then decreased

and reached the maximum during the mature forest period

whereas the benefits of soil carbon and nitrogen storage increased gradually. Moreover

the benefits of ecosystem services on the shady slope were higher than those on the sunny slope. ② Forest age was the dominant factor causing the change in the ecosystem services trade-off relationship (p<0.05)

whereas slope aspect did not have a significant effect on the trade-off of ecosystem services (p>0.05). Soil carbon retention and soil nitrogen retention were synergistic

and the trade-off of water conservation with other ecosystem services was relatively high. ③ The ecosystem services of the plantation were positively correlated with different degrees with coverage

canopy density

and litter thickness

but were negatively correlated with different degrees of slope.[Conclusion] The trade-off of ecosystem services in the R. pseudoacacia plantation was higher during the middle-age and over mature periods

which is not conducive to the overall ecosystem service benefits. Drought-tolerant shrubs or native herbs should be introduced during the middle-age forest period. Regarding the management of the over-mature period

stand density should be reasonably controlled for water conservation such that the role of other ecosystem services can be promoted to improve the overall benefits.