Assessment of protected vs. degraded oak forests: A geostatistical approach based on soil and plant diversity

Assessment of forest soil and vegetation characteristics provides basic and essential information for the protection and rehabilitation measures in forest ecosystems. Therefore, regard to the importance of this issue, the distribution of different soil properties and vegetation diversity in relation to conservation management and degradation investigated in the oak forests of Ilam province using geostatistical methods. First, in each area, 50 plots were determined by systematic random method. In each plot, the percent cover of plant species estimated. Also, soil samples (0 to 20 cm) collected by selecting three random points in each plot. After calculating different soil properties and understory plant species diversity, the accuracy of Kriging and Inverse Distance Weighting (IDW) in estimating of variables investigated. Then the distribution map prepared for those variables that their estimation accuracy was acceptable. The results showed that there is a spatial dependency between soil properties and diversity, richness and evenness and their distribution map of these variables can be prepared with suitable accuracy. So, the distribution map of variables which had appropriate accuracy and estimation accuracy (R2> 0.5) was provided that included saturated moisture percentage (IDW method), soil salinity (Kriging), exchangeable magnesium (IDW), calcium (Kriging), Lime percentage (IDW), total Phosphorus (IDW), organic carbon (Kriging), soil bulk density (IDW), litter rate (IDW), total nitrogen (IDW) and Shannon–Wiener index (Kriging). The results of this study showed that habitat degradation weakens the spatial structure of soil attributes and plant species diversity.