Evaluation of fungal and enzymatic activities in relation to soil quality along altitudinal gradient in Hyrcanian forests (Case study: Vaz watershed - Mazandaran province)

The activity of fungal and enzymes are important for soil quality in forest ecosystems. Altitudes above sea level (a.s.l.) are important for their impacts on biological and non-biological characteristics of soil by effecting distribution of fungal communities and their enzymatic activities. The aim of this study was to investigate fungi diversity and soil enzyme activities in relation to soil quality index (SQI) along an altitudinal gradient (0, 500, 1000, 1500, 2000 and 2500 m a.s.l.) in Vaz watershed- Mazandaran province. In each elevation level, nine 400 m2 plots were investigated for tree cover and soil characteristics. The soil physical, chemical, and enzymatic properties were measured by conventional laboratory technique. To profile fungal community, ITS region was PCR amplified using barcoded primers and sequenced using next-generation sequencing technologies. Our results showed that the highest SQI and leucine aminopeptidase activities were observed at the lowest elevation level with the highest soil microbial respiration, nitrogen and temperature. The highest percentage of ectomycorrhizal and yeasts fungi, as well as the highest activates of arylsulfatase and acid phosphatase enzymes were associated with middle SQI in 1500 m altitude level with a high correlation with soil carbon concentration. The lowest SQI, along with the activity of saprotrophic fungus and β-glucosidase and cellobiohydrolase enzymes was noted in higher elevations. It can be concluded that with increasing elevation, SQI is decreased due to a reduced ectomycorrhizal fungi population and decreased activities of carbon/nitrogen-dependent enzymes in the absence of coexisting tree species.