The Prototype of Forest Structural Instability in Persian Oak (Quercus brantii) Slash and Burn Agricultural Areas in the Zagros, Western Iran

In the Zagros ecosystem, many local communities rely on traditional slash-and-burn agriculture for their livelihoods, yet this practice has resulted in significant forest damage. This study delves into the structural impact on trees within these agricultural zones. We conducted a comprehensive 100% sampling, documenting both quantitative and qualitative traits of all trees in the study area. Quantitative data encompassed species type, regeneration method (coppice or standard), Diameter at Breast Height (DBH), tree height, crown major and sub-diameters, tree health, and the proportion of cut and damaged roots. To ascertain the number and volume of felled trees across three locations, we analyzed reports of natural resource violations spanning 2001 to 2021. In the absence of available 2001 data, samples were extracted radially from the diameter at breast height using an increment borer to detect structural changes by 2021. We calculated diameter increment during this period. Comparison of canopy areas in 2021 to those in 2001 at Kasehkaran, Avalviar, and Cheshmeh Pahn-e Rashid sites revealed declines from 54,686 to 43,180 m², 15,830 to 12,762 m², and 22,232 to 19,064 m² respectively. Over the second period, tree frequency in diameter classes decreased across all three areas compared to 2001. Initially, total tree volumes in Kasehkaran, Avalviar, and Cheshmeh Pahn sites were 153 m³, 1,174.5 m³, and 565.6 m³ respectively in 2001. However, by 2021, these volumes decreased to 144 m³, 822 m³, and 515 m³ respectively. Over the past two decades, 118, 523, and 132 trees were removed from these areas. A paired t-test with a 99% confidence level demonstrated significant mean volume differences between the two periods in all habitats. Despite appearances, shifting agriculture has undergone structural degradation over time. We recommend specialized monitoring by relevant agencies, in addition to implementing standard protective measures.