Sawing yield estimation of defective logs in Olea europaea L., Robinia pseudoacacia L., and Castanea sativa Mill. species growing in Southern Italy

Abstract Key message This study assessed sawmill efficiency for olive ( Olea europaea L.), black locust ( Robinia pseudoacacia L.), and chestnut ( Castanea sativa Mill.) logs in Southern Italy evaluating the impacts of taper, ovality, sweep, and fluting defects on sawing yield. Taper was the most significant defect, especially for olive and chestnut logs. Black locust showed stable yields (70%), highlighting its commercial potential. The results of this study demonstrate that the quality and defectiveness of logs—particularly taper and ovality—significantly influence the sawing yield of the investigated species and emphasize the importance of selecting high-quality raw materials to reduce waste and enhance the economic value of Mediterranean hardwoods. Context The hardwood sawmilling sector plays a crucial role in the wood supply chain, where the efficiency of the sawing process is directly influenced by the quality of raw material and the presence of inherent log defects. Accurate evaluations of sawing productivity and yield potential are therefore essential to minimize wood waste, enhance value recovery, and support sustainable forest resource utilization. Aims This study aimed to evaluate the sawing yield of hardwood sawn timber from olive ( Olea europaea L.), black locust ( Robinia pseudoacacia L.), and chestnut ( Castanea sativa Mill.) logs sourced from Southern Italy, investigating the impact of four log defects: taper, ovality, sweep, and fluting defects across different diameter classes. Methods Over 200 logs were analyzed for sawing yield using a vertical band saw and adopting a live-sawing pattern. Defects were measured and statistically assessed. Yield was calculated as the ratio of sawn product weight to raw log weight. Results Taper significantly reduced yield, particularly in olive and chestnut logs, and, to a lesser extent, ovality was found to be a defect affecting yield only for olive trees and for the smaller diameter class. Black locust and chestnut maintained stable yields (70%), demonstrating strong commercial potential. Olive logs showed competitive yields in larger diameter classes, despite their irregular shapes. Conclusion The results of this study demonstrate that the quality and defectiveness of logs—particularly taper and ovality—significantly influence the sawing yield of Mediterranean hardwoods. Despite these challenges, species such as olive, black locust, and chestnut have shown yield values comparable to other widely used hardwoods, confirming their suitability for commercial applications. These findings support the potential for more sustainable and efficient use of locally available hardwood resources in Mediterranean forestry contexts.