Agrochemical properties and fertility potential of mountain-forest soils in the Lankaran-Astara region supporting persian ironwood (Parrotia persica) and caspian locust (Gleditsia caspica)

This study investigates the relationship between the distribution patterns of two relict tree species-ironwood (Parrotia persica) and Caspian locust (Gleditsia caspica) - and soil conditions in the mountain forest ecosystems of the Lankaran-Astara economic region. The research was conducted between 2022 and 2025. A total of 112 soil samples were collected from 28 soil profiles and analyzed for total organic carbon (TOC), FTIR spectroscopy, pH, particle size distribution (laser diffraction), trace element composition (ICP-MS), and clay mineral composition (XRD). The results indicate that P. persica reaches its maximum density (410 trees/ha) on northern slopes at elevations of 600–800 m, whereas G. caspica attains higher density (265 trees/ha) on southeastern slopes at 400–600 m. Mountain forest brown soils formed under P. persica show higher humus content (6.2%), TOC (4.2%), and slightly acidic pH (6.0), while mountain forest yellow and brown soils under G. caspica are characterized by moderate humus content (3.5%), TOC (2.4%), and neutral pH (6.5). Soils under P. persica are enriched in Zn (54 mg/kg) and Cu (14.5 mg/kg), whereas those under G. caspica contain higher concentrations of Fe (5400 mg/kg) and Mn (400 mg/kg). The soils under P. persica exhibit high potential for organic farming, while those under G. caspica have neutral pH, making them suitable for a wide range of crops.

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