Variation in soil nutrient variables in relation to altitude and aspects in Sikilsdalen and Heimdalen of Southeast Norway
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The study investigates the variation in soil nutrients variables in an altitudinal gradient and aspect of Sikilsdalen and Heimdalen of Southeast Norway. The study was carried out with the data collected during the field work. The aim of the study was to analyse the variation in soil variables along altitude (1000 to 1575m) and from the slope with different aspect (north-facing slope/south-facing slope). Soil samples were taken in the homogeneous vegetation plots in every 25 meters of both mountains. Soil variables, volume weight, pH, Ca, Mg, K, P and Loi (organic carbon) were analyzed in a laboratory. The data was analysed by the MINI TAB program7.1. Pearson correlation, Regression, ANOVA and PCA analysis were done to examine the data from all perspective so that clear significant correlation and difference can be found along altitude and aspect. Pairwise comparisons were done by Tukey’s methods to find the significant mean difference with confidence intervals. The method for soil analysis was followed by the standard soil analysis methods written by Krogstad, (1992). Soils of both northern (SF) and southern (NF) valley were acidic as pH was range from 4.1 to 5.3. Soil nutrients are correlated with each other but the significant correlation with altitude was showed only by P, Mg, Ca and Vw with different trends. In the southern slope (north-facing slopes) of both mountains, K, Mg, Ca, and Vw showed significant trends along altitude whereas in the northern slopes, P showed the significant difference with altitude in Sikilsdalen and none of the soil variables showed any significant difference with altitude in Heimdalen. The null hypothesis was rejected only for pH in both mountains. There is increasing tendency in pH with altitude in both valleys, but with different directions in Sikilsdalen and Heimdalen. All the soil variables were found high in the middle part of both mountains. More variation was observed in northern aspect than the southern aspect due to more vegetation. Vw in both slopes increased with altitude and most other soil variables decreased with altitude. The effect of Loi was smaller in Heimdalen compared to Sikilsdalen.