Spatial Variability and Multivariate Assessment of Soil Physico-Chemical Properties in Kanger Valley National Park, India

Abstract

Soil physicochemical properties are basic soil fertility parameters and soil ecosystem function in tropical forests as they control soil nutrient cycling, soil organic matter decomposition and the productivity of vegetation. In the present study, spatial variations of soil physicochemical properties were explored in Kanger Valley National Park, Chhattisgarh, India, by Pearson correlation analysis and Principal Component Analysis (PCA). Nine representative sites were sampled and composite samples of the surface soil (0-10 cm and 10-20 cm) were taken for each sample site, and analyzed for pH, electrical conductivity (EC), organic carbon (OC), available nitrogen (N), available phosphorus (P), available potassium (K), particle density (PD), and bulk density (BD). Soils were found to be non-saline (pH 5.03 to 6.05) and had low electrical conductivity (0.08 to 0.34 dS m⁻¹), which is good for forest vegetation. Organic carbon content ranged between 0.64–0.72%, available nitrogen (160.25–179.75 ppm), phosphorus (9.23–13.05 ppm), and potassium (153.50–178.75 ppm) showed moderate fertility of the soil. The Pearson correlation values showed that there were high positive correlations between the available K and available N with organic C, and soil pH with organic C and available N, suggesting that these are more influenced by organic C than by bulk density, while the bulk density had significant negative correlations with most of the fertility parameters, indicating adverse effects of soil compaction on nutrient availability. Based on the Principal Component Analysis, the total variance was explained by two principal components with eigenvalues larger than one, accounting for 63.9% of the total variance. The first principal component (47.3%) explained the soil fertility gradient, which was dominated by soil organic carbon, pH, available soil N and soil K, and second principal component (16.6%) reflected variations in soil physical properties, mainly particle density and bulk density. PCA site scores and the biplot were able to clearly separate nutrient-rich sites from relatively nutrient-poor sites, indicating that there was a high degree of soil quality variability across the study area. The results show that organic carbon is the most important factor for soil fertility, while bulk density and particle density are secondary factors for soil variation. The results present a good baseline data for monitoring soil quality and aid sustainable conservation and management of the tropical forest ecosystems in Kanger Valley National Park.