بومشناسی جنگلهای ایران (May 2024)
Short-Term Effects of Fire on Soil Physicochemical Properties and the Vegetation Cover of Tamarix sp. Stands in Qara Gheshlagh Bonab Lagoon, East Azarbaijan Province
Abstract
Extended Abstract Background: Fire is one of the most significant ecological elements that can alter the functioning of natural ecosystems, as well as one of the most significant natural disasters that endangers the ecosystem of forests. The intensity and frequency of forest fires are increasing daily due to the consequences of global climate change and population growth in sensitive areas. This factor not only damages individuals and property but also poses a serious risk to environmental preservation and the well-balanced ecological conditions of vegetation. Worldwide, thousands of fires in natural areas result in unquantifiable and unfathomable calamities each year. For many years, this problem has been the subject of investigation. The investigation of the fire that occurred in 2021, the conditions of its creation, and its effect on the soil and vegetation characteristics of the Qara Qeshlaq Lagoon are the most important goals of this research. Methods: An area of approximately four hectares of the Qara Gheshlagh Lagoon was burned twice on April 16, 2021, in two different time frames (hours) at 15:30 and 19:30. This area was chosen to investigate the effect of fire on the geological characteristics and vegetation of the wetland. Furthermore, a control area (unburned) was chosen to be close by, of the same size and at the appropriate distance from the burned region. The vegetation was sampled along a transect that ran along these regions. Given that the vegetation in both the burned and control areas is densely covered by Tamarix, 40 rectangular sample plots (a total of 80) with an approximate area of 10 m2 (5 ×2 m) and a distance of 20 m from each other were used to record the height, collar diameter, dbh, small and large diameters of the crown, the number of sprouts, and stem health traits. The percentage of grass cover was determined using a 1-m2 sample plot in the center of the sample plots. Additionally, five randomly selected sample plots were used from the center to measure the soil physicochemical characteristics, including its acidity, electrical conductivity, organic carbon, percentage of lime, percentages of clay, silt, and sand, and absorbable potassium and phosphorus. A soil sample was taken from a depth of 0-10 cm. After determining the normality of the data distribution with the Kolmogorov-Smirnov test, the Mann-Whitney and independent t-tests were used to compare the average quantitative characteristics of the vegetation cover and soil characteristics in the two burned and control areas. In addition, the principal component analysis (PCA) was utilized to explore the most essential fire-related elements in vegetation cover and soil. Results: At the 99% confidence level, the average collar diameter in the burned region was significantly higher at 4.41 cm than in the control area (3.17 cm). The average dbh (1.64 vs. 1.24 cm) and the number of sprouts (20.05 vs. 14.76) varied significantly in the burned and control areas, with a 95% confidence level. Additionally, a significant difference was observed between the average tree height (1.96 vs. 1.36 m), the percentage of grass cover (70.19 vs. 50.28%), and the stem health (all healthy stems versus all burnt stems) in the control and burned areas at the 99% confidence level. After about a year of the fire, there was a difference in pH characteristics (7.12 vs. 6.73) and sand (27.10 vs. 22.90%) in the two burned and control areas, with a significant difference at the 95% confidence level. A significant difference in the properties of organic carbon (2.86 vs. 1.71%), phosphorus (71.63 vs. 34.28 mg/kg), and potassium (921.40 vs 606.60 mg/kg) was seen in these two areas at the 99% confidence level. The PCA results revealed an effect of fire on the organic carbon, phosphorus, and available potassium parameters. Among the vegetation cover characteristics, the most effects belonged to the dbh, the collar diameter, tree height, and the large and small diameters of the crown with a factor load greater than 0.8. Conclusion: According to the current study, the quantitative features of the trees in the wetland were impacted in the burnt area, and changes occurred in vegetation and soil characteristics. As a result, all of the soil properties were significantly higher in the burned region than in the control area. Other than the collar diameter factor, other plant features in the burned region dropped dramatically. Thus, careful management and conservation of such areas following the fire is critical to restore the strength and potential of ecosystems to ensure the continuance of survival and sustainability. Therefore, it is advised to investigate the long-term impacts of fire on vegetation alterations and to accelerate the reconstruction process of the region by protecting such ecosystems and carrying out restoration operations.
