Taxonomic and Genetic Pedodiversities on Different Geomorphic Units in Marand Region, East Azarbaijan

In this research work, taxonomic richness and pedodiversity were used for studying soil evolution on rock pediment, mantled pediment, piedmont plain and alluvial plain geomorphic units and genetic richness was also used to evaluate the effect of classification system on genetic pedorichness in Marand region. 26 pedons were excavated and sampled in different geomorphic surfaces. Calculation of indices was done considering soil individuals and soil type areas at different levels of USA Soil Taxonomy System (order, family) as well as diagnostic horizons. Soil richness at the level of order increases from rock pediment to alluvial plain and alluvial plain with four suborders is the richest geomorphic unit. The index shows only a little difference between great group and subgroup in mantled pediment and piedmont plain and at the family level, indices increase in all geomorphic units except alluvial plain. The number of taxa increases from order to family level and rock pediment has the least richness by impossibility of deposition processes. The taxonomic diversity index on each geomorphic unit increases from order to family by increasing in taxa richness and diversity indices calculated based on pedon numbers are higher than those based on area coverage. Cambic horizon is the most dominant horizon in the study area and piedmont plain is genetically the richest geomorphic unit. Genetic pedodiversity depends on soil classification system and soil taxonomy system tries to homogenize the soils in geomorphically active regions.