soil quality indices in pure and mixed forest stands of southern caspian region

the present study aimed to assess pure planted species (i.e., alnus subcordata l., poplus deltoids l., taxadium distichum l. rich) and a mixed natural forest (i.e., dominated by quercus castaneifolia c. a. mey. - carpinus betulus l. - parrotia persica c. a. meyer) on basis of some soil quality indices in mazandaran province, northern iran. sixteen samples per stand were taken from the top 10 cm of soil and bulk density, texture, water content, ph, ec, organic c, total n, available nutrients, earthworm biomass, microbial respiration, fine root biomass with organic c and total n of litter layer were determined. nine criteria (i.e., silt, ec, k, ca, mg, microbial respiration, fine root biomass, nitrogen mineralization and litter c/n) were selected according to principal component analysis (pca) as minimum data set (mds). the analytical hierarchy process (ahp) method was employed to assign the data integration in an index. the calculated overall priority based on nine criteria, showed that the a. subcordata forest type had higher ecological potential (0.370) compared to the other stands. whereas, p. deltoids mixed natural forest and t. distichum with ecological potential of 0.295, 0.213 and 0.122 had next priorities, respectively. as a conclusion, the n-fixing species, a. subcordata, was found more efficient in improving soil quality in degraded forest regions