Changes in vegetation parameters due to fire (Case study: woody rangelands of Veysian site in Lorestan province)

Fire affects quantitative and qualitative indicators by changing stable plant communities, changing genetic diversity and reducing plant and animal species and the succession and steps are effective. The severe effects of fires on the reduction of soil protection, production and changes in plants palatability, animal breeding conditions, challenges in the livelihoods of farmers, disturbance in ecosystem cycles, and on a large scale the impact on climate change, add to the sensitivity of the issue. Therefore, wildfire in natural areas is an ecological and economic risk and has profound effects on vegetation and soil and economic production of the country. So, it seems necessary to know the effects of fire, which is the purpose of writing this article.

To conduct this study, Veysian site with an average height of 1580 meters above sea level and an average annual rainfall of 470 mm was selected. Then, 200-meter transects with four numbers and a distance of 100 meters from each other and 10 squares of one square meter fixed on each of them formed the sample units in each field. This sample unit was executed exactly in a similar and homogeneous arena in its immediate area, which is protected from fire and is called the control area, with the same quality. This site was burned for the second time in 2011 and 2016, and it was surveyed in 2018 and 2019. In this site, 80 plots of one square meter each year and finally 160 plots were studied in two years and in two areas of control and treatment. After sampling, the data were normalized and analyzed using T-TEST and ANOVA in the SPSS version 22 software environment and comparing the average data using the DUNCAN method.

In this research, the general comparison of the control and treatment areas in all sites shows that there is a significant difference between the control and fire treatments at the level of 1%. In other words, the fire has been able to create major changes in terms of quantitative and qualitative indicators in the sites. The fire has obviously increased the forbs relatively compared to the grasses due to the overall decrease in canopy cover and production. The dominant species in this vegetative form is the annual species Coronilla scorpoioides (L.) Koch, which prevailed over other species after the fire. Also, the fire caused the reduction of the condition rangeland from average to poor and the trend of the status from +22 points in the control to +1 in the fire treatment. According to the annual increase of rainfall from 356 mm in the first year to 778 mm in the second year, data shows that the amount control area of production has increased from 1276 to 1454 kg per hectare (178 kg), while the burned area has decreased by 2 kg.

Covering the soil surface and its quality is one of the most important factors for soil health protection and reducing erosion and preventing of splash erosion. Fire resistance is different in different species in a vegetative form. Plant species whose seeds are more easily moved by the wind are more successful in reestablishing in the burned zone and this point is independent of their vegetative form. In this research, fire is like preparing the field for planting plants, so reviving fire fields with high-quality species is a necessity. Considering that the fire destroyed the positive aspects of the soil and vegetation and the management of burnt areas is very specialized and sensitive. Therefore, according to the existing conditions, it is not recommended to create a fire either intentionally or accidentally in this vegetation area of Iran.