Document Type : Research Paper
Authors
1 MSc. in Rangeland Management, University of Kurdistan, Department of Range and Watershed Management, Faculty of Natural Resources, University of Kurdistan, Iran
2 Assistant professor, Department of Range and Watershed Management, Faculty of Natural Resources, University of Kurdistan; Sanandaj, Iran
3 Associate Professor, Faculty of Natural Resources, University of Tehran, Karaj, Iran
Abstract
Background and Objective
Fire is a significant ecological factor that influences rangeland ecosystems, particularly in arid and semi-arid regions, where it plays a crucial role in the growth, development, and evolution of plant species. Historically, controlled burning of vegetation in natural ecosystems has been one of the simplest methods for altering and enhancing habitats, as well as for eliminating pests, diseases, and undesirable plants, while also modifying vegetation cover. Understanding the effects of fire on the characteristics of rangeland vegetation is essential for effective post-fire management. Therefore, this study aims to investigate the impact of fire on specific vegetation characteristics and to analyze vegetation responses to fire, with the goal of improving the management of the Sanandaj rangelands.
Methodology
For this study, three areas Khalichian, Hasanabad, and Haft Asiab located around Sanandaj and affected by fires one to three years prior were selected. Following field surveys and sampling, the flora of these areas was identified using available resources. Vegetation types were determined through the physiognomic-floristic method. Six sites were established for vegetation sampling, comprising three burned sites and three control sites. Each pair of burned and control sites was matched based on topographic conditions, including elevation, slope percentage, and slope direction, to minimize the effects of environmental gradients and focus on the impact of fire. In each site, two transects (one along the slope and one perpendicular to it) were established, with 15 plots along each transect, resulting in a total of 12 transects and 180 plots. Within each plot, vegetation characteristics such as the percentage of canopy cover of plant species, bare soil, stones and gravel, and litter were estimated. The Shannon-Wiener index was utilized to calculate diversity and evenness, while the Margalef index was used to assess richness. An independent t-test was conducted to compare the mean vegetation characteristics.
Results
The results revealed a significant decrease in the canopy cover of shrubs in the burned sites, accompanied by notable increases in the cover of grasses and both annual and perennial forb plants. Total canopy cover, bare soil percentage, production, and species richness significantly increased in all three areas as a result of fire, while litter significantly decreased. Total rangeland production in the fire-affected sites was significantly higher than in the control sites (P < 0.01), with increases of 26.48%, 26.48%, and 40.14% observed in Khalichian, Hasanabad, and Haft-Asiab, respectively. The difference in the species diversity index (Shannon-Wiener index) was not significant in Khalichian; however, it showed a significant increase in the other areas. Comparisons of the Margalef species richness index indicated that fire enhanced species richness in all three areas, with increases reaching significance at the 1% level. The species evenness index exhibited a significant increase in Hasanabad and Haft-Asiab, but not in Khalichian. An examination of plant composition in the studied areas indicated that fire reduced the prevalence of woody species while promoting an increase in herbaceous plants.
Conclusion
This study concluded that fire generally results in an increase in live vegetation cover, a reduction in litter, and an increase in bare soil. Additionally, fire alters plant composition, favoring herbaceous plants over woody species. Therefore, it is recommended that controlled burning be implemented in grasslands where plant composition has shifted and woody species have proliferated. Such practices should be considered alongside other economic, social, and environmental factors to enhance rangeland conditions.
Keywords
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