在全球变暖与大气CO₂浓度升高背景下，植被叶面积增加与生长季延长共同驱动植被显著“变绿”趋势，然而二者间是相互权衡还是协同变化尚不明确。利用多源遥感数据，分析了2003—2020 年中国落叶阔叶林最大叶面积指数和生长季长度的变化规律。结果表明：①叶面积增加和生长季延长为负相关关系，东北地区落叶阔叶林叶面积增加较少而生长季延长更多；北方过渡区相反，两种策略存在权衡机制。②这种权衡关系可由树高解释，矮树的基底叶面积小、叶面积与边材面积比高，其叶片在CO₂的施肥效应影响下倾向于增加叶面积；高树的叶面积大、叶面积与边材面积比较低，受地表温度影响而更依赖于延长生长季。③生态系统光能利用效率随树高增加而降低，获取型策略的矮树通过增加叶面积以提升光合作用速率，而保守型策略的高树选择延长叶片生长季但降低光能利用效率。研究为理解气候变化背景下中国地区落叶阔叶林的叶片适应策略提供了新见解，并拓展了对生态系统功能的潜在影响的认识。

Under the context of global warming and rising atmospheric CO₂ levels, increases in vegetation leaf area and longer growing seasons both contribute to a clear greening trend. However, whether these two factors show a trade-off or work together remains unclear. In this study, we used multi-source remote sensing data to analyze the patterns of maximum leaf area index (LAImax) and growing season length (LOS) in deciduous broadleaved forests (DBF) across China from 2003 to 2020. The results indicated that: ① An increase in leaf area is negatively correlated with the extension of the growing season. In Northeast China, deciduous broadleaf forests show relatively small increases in leaf area but more significant extensions of the growing season. Conversely, in the northern transitional zone, the opposite pattern is observed, suggesting a trade-off between these two strategies. ② Tree height plays an important role in explaining this trade-off. In the northern transitional zone, where dwarf trees dominate, forests tend to adopt a strategy of increasing leaf area with only small changes in growing season length. By contrast, in Northeast China, where tall trees are more common, forests are more likely to extend the growing season while showing limited leaf area change. This spatial difference reflects the contrasting physiological adaptations of trees with different heights. ③ These contrasting strategies are jointly shaped by climate factors and vegetation traits. Rising atmospheric CO₂ is more likely to promote leaf area increase in dwarf trees, whereas higher surface temperature has a stronger effect on growing season extension in tall trees. In addition, dwarf trees generally have lower initial leaf area and a higher leaf-to-sapwood area ratio, which favors leaf area increase, while tall trees tend to extend the growing season because of their larger basal leaf area and lower leaf-to-sapwood ratio. ④ The two strategies have different ecosystem consequences. Dwarf trees can enhance photosynthesis and ecosystem productivity by increasing leaf area. In contrast, tall trees mainly adapt by extending the growing season, but their lower photosynthetic efficiency may reduce ecosystem productivity.This expansion provides additional context to the ecological dynamics, emphasizing how specific strategies driven by tree height and climate factors interact to shape vegetation function across regions.