Effect of Soil Properties on Above-ground Net Primary Production in Moghan-Sabalan Rangelands, Iran

The aim of this study was to investigate the relationship between total community and Plant Functional Types (PFTs) Aboveground Net Primary Production (ANPP) with soil variables. Sampling done in two altitude gradients (20-3300m) and 25 sites at the rangelands of the northern Ardabil province in 2016. In each site, PFTs ANPP and soil were sampled. In laboratory soil variables including Soil Texture, Dispersible Clay, Bulk Density, Volumetric Soil Water Content, Saturation Percent, pH, EC, Organic Matter, Particulate Organic Matter, Calcium, Magnesium, Phosphorous, Sodium, Soluble Potassium, Exchangeable Potassium, Lime and Carbonate were measured. Cluster analysis was used to group sites based on soil variables. ANOVA and Tukey tests were employed to compare the value of ANPP and soil variable at different groups resulting from cluster analysis. Then, linear regression was used to investigate relationship between ANPP and soil variables. Based on cluster analysis, 25 sites were divided in four soil types and results showed that the value of PFTs and total ANPP and 26 soil variables from 37 soil variables had significant differences between grouping sites. Regression model showed that SK and P in first depth of soil were effective on grasses (R2=0.51), VWC and P in the first depth and EK and Mg in the second depth were effective on forbs ANPP (R2=0.61), Clay, VWC, Mg and POM in the second depth were effective on shrubs ANPP (R2=0.71) and pH in the first depth, Sand and POM in the second depth were effective on total ANPP (R2=0.76). According to the obtained models, ANPP changes can be predicted by soil variables. Also, based on the result, PFTs can be a suitable indicator for soil condition of rangeland. So, the results of the present study can be used to refine rangelands in this area and even to extend them to other areas.