Geostatistical assessing of some soil properties variability due to the oak land deforesting in Mokhtar plain, Yasouj

Assessing the variation of different soil properties through the land use changes may provide useful information for land managers. The present study aimed to assess the soil quality variation due to the land use changes from dense (non-degraded) to semi-dense (degraded) oak forest and then to dry-farming in Mokhtar plain located in Yasouj region. A total number of 100 surface soil samples were collected in order to analyses of the selected physicochemical soil properties. After statistical analyses, the continuous distribution maps were prepared for all soil variables using ordinary kriging and inverse distance weighting methods in ArcGIS software (ver. 10.2; ESRI). Analyses of the average values of selected soil properties showed that after changing the land use from dense to the degraded oak forest and then to dry-farming, organic matter and CEC changed in a decreasing trend and bulk density changed in an increasing trend. Moreover, electrical conductivity, carbonate calcium equivalent and clay percentage decreased in lower contents; whereas soil pH and sand percentage inconsiderably increased. Among the soil properties, organic matter content as one of the most important soil quality indices showed a significant change with an average of 6.74%, 3.42% and 1.58% in dense forest, degraded forest, and dry-farming lands, respectively. Supporting these findings, spatial distribution maps of the selected properties revealed that the most optimum soil properties were found in the southwest of the studied area, i.e. in the soils covered with dense oak forest; whereas increasing distance to the dry-farming lands in the northeast of the area, the selected soil properties were adversely changed. According to these findings, it can be stated that wide deforesting and land use change have been led to the considerable soil quality decline and therefore if deforesting will not be stopped a huge portion of the studied soils may lose their vital capabilities.