Biomonitoring of Heavy Metals in Mediterranean Pine Ecosystems: Implications for Ecological Resilience Capacity and Sustainable Forest Management

Abstract

This study comprehensively evaluates the elemental composition of soil and Pinus species needle samples across 25 distinct plots established along the D825 highway in Kahramanmaraş, Türkiye. Located at the confluence of the Mediterranean, East Anatolian, and Central Anatolian regions, this area represents a critical ecological transition zone. A total of 75 soil and 75 needle samples were analyzed in triplicate to assess heavy metal contamination and potential toxicity risks across these elevation gradients. According to the results, the Geoaccumulation Index (Igeo) values for all examined metals remained below zero, categorizing the study area as “unpolluted.” Enrichment Factor (EF) analyses confirmed the lithogenic origin of Cr, Mn, and Ni; however, Lead (Pb) and Cadmium (Cd) exhibited an EF of 1.34. This ‘minimal enrichment’ could potentially be associated with anthropogenic pressures, possibly stemming from traffic emissions on the highway. Although current metal levels fall below global toxicity thresholds (WHO/FAO), the positive skewness and high variation in Pb and Cd distributions suggest a likelihood of localized accumulation, which may warrant systematic monitoring. The original contribution of this study lies in its integrated assessment of plant–soil barrier mechanisms within this unique transition zone, demonstrating how forest ecosystems maintain resilience capacity despite ophiolitic parent material contributions. While soil Cr and Ni levels were elevated due to the geological structure, plant tissue concentrations remained within safe physiological limits, suggesting effective stabilization within the soil-biomass matrix. The findings suggest that these forest ecosystems play a key role in maintaining ecological health and environmental sustainability against potential anthropogenic encroachment in this strategic intersection.