The effects of afforestation are of great importance for terrestrial nitrogen (N) cycling. However, theconsequences of afforestation for soil nitrogen (N) dynamics remain poorly quantified. We investigatedsoil net N mineralization and nitrification rates as well as the inorganic N (NH4+-N and NO3？-N) con-centration in the top soil (0–10 cm) in a woodland, shrubland and adjacent cropland in the DanjiangkouReservoir region of central China using the in situ closed-top tube incubation technique over one year.Afforestation significantly decreased the soil net N mineralization rate and soil inorganic N concentrationbut increased the soil NH4+-N concentration and soil ammonification rate. The major form of soil inor-ganic N was NO3？-N in the cropland versus NH4+-N in the woodland. The soil net N mineralization andnitrification rates were more sensitive to soil moisture than to soil temperature and were positively cor-related with soil moisture. In contrast, the soil net N mineralization and nitrification rates were negativelyrelated to SOC and the C:N ratio. These results suggest that afforestation could decrease N mineralizationand availability due to increasing the recalcitrant C input and plant N uptake, which might in turn causeprogressive N limitation over the long term.