Effect of Pistachio (Pistacia atlantica) canopy on the spatial distribution of soil chemical characteristics (Case study: Sarvabad, Kurdistan)

In arid and semi-arid ecosystems, isolated trees have an important effect on soil properties and could determine the structure of the soil fauna communities and herbaceous species under the tree which could influence these types of ecosystems. The aim of this study was to find out the effect of tree canopy on the spatial distribution of soil nutrients (OC, N, P, K, Na and Li) with varied chemical characteristics. In this research, soil samples were taken under and around a pistachio (Pistacia atlantica Desf.var.Kurdica) tree in Sarvabad region, West of Iran. The samples were taken every 2 m and then at 50 cm intervals in a regular grid of 20 m × 20 m around the tree for analyzing the spatial properties using geostatistical techniques. Total nitrogen (N) content similarly to soil organic carbon (OC) was higher under the tree. Phosphorus (P) content also was higher under the tree canopy. Potassium (K) decreased with distance from the tree base. Sodium (Na) had a medium spatial distribution related to tree canopy, while Lithium (Li) showed a sparse spatial pattern and its distribution seems to be independent of the tree position. These results support the hypothesis that the presence of a tree affects differently the spatial distribution of the various nutrients depending on their chemical characteristics.