Effects of pure mixed species on soil nutrients, soil organic carbon and total nitrogen stock capacities

In this study, some soil properties (bulk density, soil pH, soil sand, silt and clay contents), soil organic carbon and total nitrogen stock capacities of pure and mixture stands of Scots pine and fir tree species were studied using 6 different soil depths (0-5 cm, 5-10 cm, 10-15 cm, 15-20 cm, 20-25 cm and 25-30 cm). Mean bulk density was 0.60 for fir pure stands, 0.57 for Scots pine pure stands and 0.54 for Scots pine and fir mixture stands. Mean soil pH was 7.31 for Scots pine pure stands, 7.29 for Scots pine and fir mixture stands and 6.99 for fir pure stands. Pure Scots pine stands had the highest sand (50%) and silt (43%) followed by fir pure stands (46%) and (37%), and Scots pine and fir mixture stands (43%) and (20%). Percent clay was however higher for Scots pine and fir mixture stands (37%) than both pure Scots pine and fir stands which had similar clay (33%). Pure Scots pine stands had the highest soil organic carbon and total nitrogen (6.19% and 0.30 % respectively) followed by mixture stands of Scots pine and fir (4.42% and 0.25% respectively) and pure fir stands (3.44% and 0.20 % respectively). As for the SOC and TN stock capacities, mean soil organic carbon stock capacity was also highest for pure Scots pine stands (95.8 Mg C ha-1) followed by mixture stands of Scots pine and fir (70.0 Mg C ha-1) and pure fir stands (57.7 Mg C ha-1). Similarly, pure Scots pine stands had the highest mean total nitrogen stock capacity (4.55 Mg N ha-1) followed by mixture stands of Scots pine and fir (3.98 Mg N ha-1) and pure fir stands (3.38 Mg N ha-1).