Changes of understory species diversity and richness in relation to overstory and some edaphic factors in central Zagros forest types

This study explores the relationship between diversity of herbaceous understory of forest types with tree layer as well as some edaphhic factors in central Zagros. To do this, tree layer of the forest types were randomly sampled using 24 sample plots (500 m2) and herbaceous understory of these forest types were randomly sampled using 288 sample plots (1 m2) at the growing season. In main plots (tree layer), in addition to physiographic features, density, coppice shoots and tree canopy area, soil variables were measured from soil samples taken from the depths of 0-10 and 10-30 cm. In plots sampled from herbaceous understory (1 m2 plots), in addition to measuring species richness, the percentage of species was recorded as an indicator of the abundance. Results showed that the values of richness indices (total richness, Menhinic, and Margalef indices) and diversity indices (Shannon-Wiener and Alpha Fisher diversity) of herbacious layer in Quercus infectoria Oliv. Forest type was significantly higher than Q. brantii Lindl forest type. No difference was found among these types in terms of indicators of dominance, evenness and Simpson diversity indices. The results of Pearson correlation indicated that the richness and diversity indices of studied forest types is positively correlated with soil clay, silt, lime, calcium and acidity.