标题： 太阳辐射和大气CO$_2$预测湿润常绿热带森林中幼叶的产生：23年的见解 显示英文标题

标题： Solar radiation and atmospheric CO$_2$ predict young leaf production in a moist evergreen tropical forest: Insights from 23 years

摘要： 气候变化对全球生态系统产生影响，通过食物可用性等变化，直接影响和间接影响动物的行为和生存。 对于依赖叶子作为主要食物来源的动物来说，了解气候变化如何影响树木的叶子生产至关重要，但这一领域研究不足，尤其是在湿润常绿热带森林中。 我们分析了乌干达基巴莱国家公园一个湿润热带森林23年的幼叶物候数据，以研究12种被食叶灵长类动物食用的关键树种的季节性和长期模式。 我们描述了物候模式，并探讨了不同树种幼叶产量与气候变量之间的关系。 我们还评估了增强植被指数（EVI）作为湿润常绿热带森林中幼叶产量的替代指标的适用性。 我们的结果表明，树种表现出不同的物候模式，大多数物种在与雨季一致的两个季节性高峰期间产生幼叶。 降雨、云量和最高温度是预测幼叶产量季节性变化的最有信息量的预测因子。 然而，太阳辐射和大气CO$_2$是关于长期趋势最有信息量的预测因子。 EVI在年度内与幼叶产量高度相关，但在捕捉年际趋势方面效果较差。 这些发现突显了湿润常绿热带森林中气候与幼叶物候之间的复杂关系，并帮助我们理解热带食叶动物食物可用性的变化。 显示英文摘要

摘要： Climate change impacts ecosystems worldwide, affecting animal behaviour and survival both directly and indirectly through changes such as the availability of food. For animals reliant on leaves as a primary food source, understanding how climate change influences leaf production of trees is crucial, yet this is understudied, especially in moist evergreen tropical forests. We analyzed a 23-year dataset of young leaf phenology from a moist tropical forest in Kibale National Park, Uganda, to examine seasonal and long-term patterns of 12 key tree species consumed by folivorous primates. We described phenological patterns and explored relationships between young leaf production of different tree species and climate variables. We also assessed the suitability of the Enhanced Vegetation Index (EVI) as a proxy for young leaf production in moist evergreen tropical forests. Our results showed that tree species exhibited distinct phenological patterns, with most species producing young leaves during two seasonal peaks aligned with the rainy seasons. Rainfall, cloud cover, and maximum temperature were the most informative predictors of seasonal variation in young leaf production. However, solar radiation and atmospheric CO$_2$ were most informative regarding long-term trends. EVI was strongly correlated with young leaf production within years but less effective for capturing inter-annual trends. These findings highlight the complex relationship between climate and young leaf phenology in moist evergreen tropical forests, and helps us understand the changes in food availability for tropical folivores.