Comparison of Some Soil Quality Indicators of Forest Soils under Two Different Tree Species

Abstract

The study area was located at Duhok governorate, Kurdistan region, North of Iraq. Two study locations were selected under pine and oak forest cover. Five pedons were dug at each location and thirty three soil samples were collected air dried, grinded and sieved through (2) mm sieve to be used for physical and chemical analysis. pH values were indicate to slightly alkaline (7.39-8.10) and this is due to the presence of cations in increasing amounts and these soils are derived from calcareous parent material. EC values of all soil samples indicated to non-saline soils and attributed to desalinization process because affected by leaching process (0.20-0.42 dS.m-1). All exchangeable cations were concentrated at the surface and subsurface horizons (A and B horizons) and lower concentration in deep horizons (C horizon) (Ca+2=5.8-16.6, Mg+2=1.2-9.4, Na+=0.2-0.8, K+=0.48-2.49 Cmolc.kg-1), additionally at Sarki location (Oak forest) were relatively high values comparing with Zawita location (Pine forest) (Ca+2=8.8-18.8, Mg+2=3.0-10.0, Na+=0.13-0.87, K+=0.76-2.68 Cmolc.kg-1). CEC values at Zawita location under Pine forest cover (11.76-33.22 Cmolc.kg-1) were relatively less than it at Sarki location under Oak forest cover (19.24-47.74 Cmolc.kg-1). Vertical distribution of calcium carbonates (28.4-380.6 g.kg-1) in all study pedons under both forest covers indicated to increase total carbonate content towards downward of pedon from upper horizon to the lower horizons and this is belong to increasing rainfall effect and weathering of parent rocks. Generally, organic matter content in study pedons at both study locations under pine and oak forest covers was directly decreased towards depth of soil pedon (8.82-101.04 g.kg-1). Depending on the particles size distribution of study soils under pine trees indicated to the studying soils were clay, clay loam, and loam texture. Conversely, soil texture under oak trees was clay. Can be concluded study soil were calcareous, Clayey, alkaline, none saline, low organic matter and CEC with depth