Optimizing Afforestation Techniques for Cedrus and Pinus in Semi-Arid Mediterranean Lebanon: Insights from Chmistar Field Trials

Abstract

Afforestation in semi-arid Mediterranean environments is frequently constrained by water scarcity, shallow rocky soils, and strong competition from herbaceous vegetation, resulting in low seedling establishment and growth. This research evaluated the effects of three planting methods (traditional pits, hoedad, and auger) and four vegetation control treatments (mulching, mowing, herbicide application, and no vegetation control) on the early establishment of three native Mediterranean conifer species (Cedrus libani, Pinus halepensis, and Pinus pinea) at Chmistar, eastern Lebanon, from 2022 to 2024. The experiment used a randomized complete block design (RCBD) with four blocks and 48 plots, with 24 seedlings per plot. Seedling survival, height growth, and root collar diameter (RCD) growth were assessed annually. Data were analyzed using analysis of variance (ANOVA) at a significance level of £ 0.05. Vegetation control had a significantly greater influence on seedling performance than planting technique. Across all species, the hoedad × mulch treatment produced the highest survival rates, reaching 97.9% in 2022 and maintaining 70.8% in 2024. P. halepensis showed the highest survival under this treatment, reaching 87.5% in 2022 and 2023 and remaining at 75.0% in 2024. In contrast, P. pinea and C. libani reached a maximum survival rate of 68.8% in 2024. Height growth was also enhanced by effective vegetation control, with maximum annual increments reaching 41.7 cm for P. halepensis, 20.8 cm for P. pinea, and 20.8 cm for C. libani. Similarly, maximum RCD increments reached 1.50 cm, 1.08 cm, and 1.24 cm for P. halepensis, P. pinea, and C. libani, respectively. Overall, mulching consistently improved seedling survival and growth across species and years, demonstrating that vegetation control is a more important determinant of early conifer establishment than planting technique under semi-arid Mediterranean conditions. These findings highlight the importance of combining effective vegetation management with site-adapted species selection to enhance afforestation success in water-limited environments.

Keywords: afforestation success, competitive vegetation, environmental conservation, pit-digging methods, seedling survival