Effect of Maintained Early Silvicultural Treatments over Two Rotations and Climate Change on Early Growth of Radiata...

Sustaining forest plantation productivity across successive rotations is increasingly challenging under changing environmental conditions. This study evaluated whether repeated establishment silviculture can maintain early second-rotation growth performance of Pinus radiata D. Don in central-south volcanic sandy soils in Chile. An experiment encompassing soil preparation (shovel planting vs. subsoiling + bedding), fertilization (B vs. NPKB), and weed control (pre-planting only vs. 2-year banded application) was conducted over two rotations. Survival, diameter, height, and stand-volume responses were compared between rotations at age 3. The second-rotation establishment period received 33% less annual rainfall than the first. Across all treatment combinations, mean survival decreased from 90.5% during the first rotation to 62.2% during the second rotation, while mean stand volume decreased from 6.58 to 1.16 m³ ha^-1. During the second rotation, weed control was the only treatment that significantly increased individual-tree and stand growth: plots receiving pre-planting weed control only averaged 38.7% survival and 0.29 m³ ha^-1, whereas those receiving additional 2-year banded vegetation control averaged 85.8% survival and 2.02 m³ ha^-1 stand volume. These findings indicate that vegetation control is key to sustaining P. radiata productivity. However, progressively unfavorable environmental conditions will jeopardize forest productivity across rotations.