Enhanced CO ₂ Response and Aging‐Related Dynamics Drive a Greater Leaf Area Index Increase in China's Planted Forests in Comparison to Natural Forests

Abstract China's forests have experienced a notable increase in leaf area, driven by planted forest expansion and natural forest conservation. However, how planted and natural forests respond differently to environmental changes remains unclear. Using leaf area index (LAI) data, propensity score matching (PSM), and machine learning, we compared these forest types under similar conditions. We show that planted forests increased their leaf area 65.8% faster than natural forests nationally. Even when comparing forests of similar age and growing conditions, planted forests grew 4.6% faster—especially in mixed and evergreen forests, where they showed stronger responses to rising CO 2 . This CO 2 ‐driven advantage declines markedly after age 40. Although natural forests eventually surpass planted forests in age‐related LAI growth, planted forests' initial advantage is stronger due to their younger age (34 vs. 57 years) and greater CO 2 sensitivity. Our findings highlight planted forests' role in carbon sequestration and could help inform improvements in ecosystem models.