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چکیده
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Abstract The Zagros forests, as one of the most important ecosystems in Iran, play a significant role in carbon sequestration. However, rare and endangered species in this region, such as Anagyris foetida L. (Ghareh Ghaj), have been less studied. Due to its unique ecophysiological characteristics, including thick leaves and a summer dormancy period, this species is an ideal model for investigating carbon and water dynamics in Mediterranean semi-arid ecosystems. The main objective of this study was to (1) develop allometric models for estimating the leaf biomass, Leaf Area Index (LAI), and Leaf Carbon Sequestration (LCS) of this species at the individual tree level, and (2) to scale these estimates using stand density to accurately determine the contribution of its leaves to carbon storage at the forest stand level (per hectare). Materials and Methods: This study was conducted in the pure habitat of this species in the Sardasir Chaleh basin, Gilan-e-Gharb County. Using systematic sampling, 30 healthy trees were selected, and biometric parameters including tree height, crown diameter, and crown area were measured. Leaf samples were collected in a stratified manner from three parts of the crown (upper, middle, lower) and transported to the laboratory. Leaf dry biomass was determined by the gravimetric method, and the percentage of organic carbon in the leaves was determined by combustion in a furnace at 450°C. Leaf Area Index (LAI) and Specific Leaf Area (SLA) were calculated using a leaf area meter and weighing: SLA was derived as the ratio of leaf area to dry weight, and LAI was computed by aggregating the total leaf area of trees on a per-hectare basis. To generalize sample tree data to the stand level, the "Mean Tree" method was used, considering a density of 253 trees per hectare. Allometric relationships between independent variables (crown diameter, crown area) and dependent variables (leaf biomass, LCS, LAI) were analyzed using linear, logarithmic, and power regression models. Results: The average leaf carbon sequestration (LCS) per hectare was estimated at 468.13 kg of carbon, CO₂ absorption at 1718.03 kg, and leaf dry biomass at 975.27 kg. The average LAI at the tree and hectare levels was 1.6 and 0.302, respectively. Correlation analysis showed that leaf biomass and LCS had a positive and highly significant correlation with crown diameter and crown area (p < 0.01). In contrast, LAI showed a significant correlation only with tree height. Among the different models, the linear regression model had the best fit, and crown area was identified as the strongest predictor for LCS (R² = 0.719). Final Conclusion: This study provides, for the first time, accurate and species-specific allometric models for estimating leaf parameters in Anagyris foetida. The findings show that despite its long dormancy period, this species has significant carbon sequestration potential, and the role of its leaves in carbon storage should not be overlooked. The developed models based on crown area can be used as a powerful and non-destructive tool for carbon monitoring, valuation of
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