Comparison of some physicochemical properties of the soil of the habitat of Gaz Shahi (Tamarix aphylla (L.) Karst) in the desert areas of southeastern Iran under the influence of fire (case study: Niatek habitat, Sistan and Baluchistan province)

Fire is one of the climatic crises and threats to the habitats of arid and semi-arid regions, and the reduction of ecological capacity intensifies the process of desertification of these ecosystems. The reaction of species in different habitats to fire is different. Therefore, the present study investigates the effect of fire on soil properties of T. aphylla in Niatek stands, Sistan and Baluchistan province, Iran.

The statistical design was completely randomized design and sampling was done as a sample line. After surveying in the area, the stands where the fire period had passed for 10 years and control stand were selected. In each stand, area (100 × 100 m) was determined on the sides of the square and the approximate distance of 50 meters was set up from the linear sides. Then, plots with (5 × 5 m) were determined at approximately 50 m from each other (three plots on each side as a transect and 9 plots in total). After setting up the plot, 5 soil samples were collected from the four corners and the center of the plot from a depth of 0-30 cm in the month of February, and 5 samples were combined and one composite sample was obtained and were transferred to the laboratory for laboratory analysis to determine the physical properties (moisture, specific gravity,) and chemical properties (sodium, Exchangeable potassium, phosphorus, nitrogen, organic matterو electrical conductivity and acidity) were determined. The experiment and statistical analysis in the physicochemical part of the soil was done using the t-test and the non-parametric Mann-Whitney U test.

According to the results, the number of 93 and 56 trees per hectare, 11 and 25 saplings under one meter height, 2 and 30% coppice trees were observed in the control and burnt stands, respectively. Examining the physical characteristics of the soil indicated a decrease in soil moisture due to fire compared to the control, and on the other hand, an increase in bulk density in the burned stand. Also, the examination of soil-chemical properties showed that the percentage of soil nitrogen, absorbable phosphorus, exchangeable potassium and soil organic carbon in the control stand was higher than the burned stand (P≤0.05). In this study, there was no significant difference in the acidity variable between the two plots of burned and control (P≥0.05). But the electrical conductivity in the burned stand was higher than that of the control stand (P≤0.05).

According to the results, fire leads to density and regeneration changes in vegetation as well as soil physicochemical properties. Although, 10 years have passed since the fire in Thamarix aphylla Ecosystems, it could not do the necessary reconstruction and reach the edaphic and vegetation balance.