Study of Soil Quality Changes in Different Forests Covers

The current study is conducted to identify and compare soil quality index in different land covers including three afforestation masses (Alnus subcordata, Populus deltoids a Taxodium distichum) and a natural mixed stand (Quercus, Carpinus betulus, Parrotia persica) located in Caspian forest seed center (Amol Province). In each of the masses, along four 200-meter transects, four soil samples (with a 20×20 m2 quadratic sampler with 10 cm depth) at 60-m intervals were taken. A total of 16 samples were collected from each forest. The soil properties including bulk density, organic carbon, total nitrogen, nitrate, ammonium, papulation of earthworms, and soil microbial respiration were measured in vitro. Finally, using the obtained values, rate of mineralization of the soil carbon, as well as the soil quality index were measured for each of the studied masses. ANOVA analysis of the physical, chemical and biological properties of the soil samples, taken from different forest stands, indicated significant statistical difference between them at level of 99%. Alnus Subcordata significantly showed the highest soil quality index (5.84 at 95%). Other masses, i.e. Populus deltoids, natural mixed, and Taxodium with quality indices values of 5.26, 4.66, and 4.40, respectively, were the next ones in the categories. The results indicated the very effective role of Alnus Subcordata forest cover in improving the quality of soil ecosystem.