Assessing the Correlation Among Soil Quality, Tree Species, and Productivity in Forest Ecosystems using SMAF Method

Abstract

Ensuring soil quality and sustainability is of vital importance in combating global climate change and desertification. Factors such as weakening of vegetation, soil erosion, compaction, and degradation reduce soil fertility, thus impacting soil quality. Evaluating soil quality accurately is essential, and the Soil Management Assessment Framework (SMAF) is a method that uses soil indicators to assess soil properties comprehensively. This study aimed to evaluate the relationship among tree species, bonitet classes, and soil quality in forest ecosystems at the watershed scale using the SMAF method. The research took place in the Karasu Watershed in Akifiye, Andırın district of Kahramanmaraş province. Soil indicators were selected from the physical and chemical properties of the soil. Soil indicators such as aggregate stability, water-filled pore volume, bulk density, carbon content, nutrient levels, pH, and electrical conductivity were used to determine soil quality indices in forest stands. Soil quality indices were determined and statistically interpreted by applying the SMAF method between tree species and bonitet classes in forest lands. Results showed that soil quality was lowest in black pine stands (69.42%) and the highest in oak stands (77.31%). Leafy stands had statistically higher soil quality. Soil quality indices ranged from 72.54 to 74.75 across bonitet classes, which are indicators of productivity (bonitet) in forest stands. No significant differences were found between bonitet classes and soil quality scores in karst forest ecosystems due to their karstic characteristics. Although soil quality may be high in karst areas, shallow soil depth limits plant growth. Therefore, a high soil quality index in karst areas can correspond to a low bonitet class. The negative effects of production activities and silvicultural interventions in forest ecosystems on soil quality can be eliminated by activities such as soil tillage. Implementing management strategies that prioritize soil protection and improvement in forest ecosystems with natural plant cover will enhance soil functionality and ensure long-term soil quality sustainability.