Document Type : Research Paper
Authors
1
Associate Prof., Forests and Range Lands Research Department, Lorestan Agricultural and Natural Resources Research and Education Center, AREEO, Khorramabad, Iran
2
Assistant Professor, Research institute of Forests and Rangelands, Agricultural Research Education and Extension Organization (AREEO), Tehran, Iran
3
Assistant Professor, Forests and Range Lands Research Department, Lorestan Agricultural and Natural Resources Research and Education Center, AREEO, Khorramabad, Iran.
Abstract
Background and Objectives: Fire is a destructive phenomenon in natural areas, affecting large parts of forests and rangelands annually with both quantitative and qualitative impacts. One of the most significant consequences is its negative impact on soil conservation, at least in the short term. The average annual area affected by fire in the world’s forests is estimated at four million square kilometers, leading to the destruction of vegetation, global warming, air pollution, loss of biodiversity, and intensified desertification.
Methodology: Given the importance of this issue, the effects of fire on soil surface cover were studied in the Farakash shrubland habitat in Lorestan province in 2017, 2018, and 2019. This site is located at geographical coordinates 33° 29’ 33” to 33° 30’ 12” N latitude and 48° 38’ 57” to 48° 40’ 56” E longitude, covering an area of 500 hectares, with an average elevation of 2050 meters above sea level. The statistical population consisted of 4 transects of 200 meters, each with 10 plots of 1 square meter spaced every 20 meters, totaling 40 plots in the treatment area. This was repeated exactly in the control field, resulting in a total of 240 plots studied. In these plots, the canopy cover was assessed using vertical images of species on the ground, along with amounts of bare soil, litter, and stones. The range condition was determined using Parker’s four-factor method, suitable for rangelands in semi-arid areas, and the condition trend was assessed by scoring the condition of the soil and vegetation. Pairwise comparisons and multivariate data averages were analyzed using a T-test, one-way ANOVA, and Duncan’s comparison method.
Results: The results showed a significant difference at the one percent level (P≤0.01) between the average values of the canopy, litter, and soil in the two areas over the statistical years. The percentage of vegetation and litter in the burnt field decreased significantly, while bare soil increased. This effect was so strong that it reduced the total plant canopy from 52.54% to 41.44%, causing a negative slope in the burned area compared to the control up to nine years after the fire. It was also found that fire led to the reduction of woody plants and the increase of grasses, changing the vegetation type from Astragalus adscendens-Daphne mucronata-Agropyron trichophorum to Agropyron trichophorum-Annual grasses. The results indicate that fire increases bare soil and erosion. This destruction is caused by quantitative changes such as the reduction of canopy, litter, and natural mulch, and qualitative changes such as alterations in plant composition, vegetative form, structure, age classes, soil seed bank, phenology, and moisture levels. Overall, fire influences the stages of soil erosion by changing vegetation type.
Conclusion: Given the current conditions in fire-affected areas, management programs such as implementing short and medium-term enclosures, determining appropriate stocking rates, seeding, and mulching with fire-resistant species compatible with the climatic and edaphic conditions of these areas can help preserve and restore vegetation and prevent erosion. Finally, due to the common ownership of Iran’s natural areas and the lack of a coherent reclamation plan for burnt areas, controlled fires are not recommended in these regions.
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