Evaluation of soil nitrogen mineralization under different tree species using various analytical methods under unique conditions (same climate, topography and soil genotype) were investigated to understand the tree effects on N mineralization. Tree species were introduced Monteri Pine (MP) and a native Oak-Beech mixed stand (OBM). A data matrix was formed from the parameters of tree species, period and incubation type, and we aimed to demonstrate how tree species induced changes in soil nitrogen mineralization under both laboratory and in situ conditions, and its relationship with intrinsic soil properties. The highest (26 mg N/kg/60 d - Tube; MP) and lowest (1.5 mg N/kg/60 d Bag; OBM) ammonium-N accumulation was detected April 2014 and June 2013, respectively. Mineral N accumulation (NH4 + NO3) was apparently 2 times higher at MP than OBM, while N mineralization was 1.4 times higher for MP than OBM. Ammonium-N values were 1.3 times higher with using the buried bag method than the tube method whilst we found 1.3 times higher nitrification with tube method than the buried bag method. Total N (R-2: 0.27; p<0.005) and organic C (R-2: 0.15; p<0.005) were positively related to ammonium-N accumulation, and there was also a positive relation with nitrate-N accumulation and pH (R-2: 0.20; p<0.001).