Relationship between Plant Diversity and Soil Characteristics in a Deciduous Cercis griffithii.L Site of Northern Zagros, Iran

Of the 49 samples taken, the relationship between surface soil factors with understory vegetation diversity was investigated (Shannons- H/, diversity index) along with the species tree by Canonical Components Analysis (CCA). Soil samples were taken and analyzed for pH, EC, C, K, Na, Mg, N, P, clay, sand, loam and organic matter.Major soil gradients of the study area were determined by Principal Component Analysis (PCA) and were used in additional analyses rather than the original factors, thus avoiding the colinearity problem. The relationship between understory species diversity with soil gradients were studied by multiple regressions and the species tree by CCA. Results showed that the relationship of soil gradients with understory diversity was best described by a unimodal curve and the species tree by a CCA graph. The most important variables were the soil gradients with understory diversity, clay percentage, silt percentage, N and Mg. Also, within the species tree were clay, silt, sand and organic matter.
However, there were unexplained variations in the relationship between soil factors and understory diversity. The remaining variation could partly be explained by the canopy cover.