Invasive shrubs are an emergent concern in deciduous forests of eastern North America. Their extended leaf phenology (ELP)—earlier leaf emergence and later leaf off compared to native shrubs and the overstory canopy—can simultaneously provide photosynthetic benefits to invasive shrubs while negatively affecting native flora and fauna through producing novel understory shade when the overstory canopy is leafless. However, phenology varies geographically, and the degree to which ELP from local-scale studies applies across the range of forests experiencing shrub invasion is unknown. In partnership with the USA National Phenology Network, we developed a citizen science campaign to record broad patterns of species-specific ELP—an otherwise prohibitively large effort. Using 1500 observations of 14 species spanning 4 years, we found that the difference in leaf phenology between native and invasive shrubs can exceed 77 days within a growing season, a gap that decreases with increasing latitude by 2.9 [1.6, 4.2] days per degree latitude in the spring, and 2.2 [0.6, 1.9] in the fall. Geographic trends in ELP provide a context for interpreting local scale phenology research while bridging inconsistent findings between existing studies and can streamline management by targeting detection and removal of invasive shrubs with leaves while natives are dormant. Furthermore, even small changes to seasonal phenology can impact forest communities, especially if there is a differential response to climate cues by nativity. After exploring broad-scale environmental variables associated with leaf phenology, we find a similar correlation with pre-growing season warmth for native and invasive shrubs, but a different relationship with dormant chill days—a variable less frequently considered for modeling spring phenology for forest productivity.

在北美东部的落叶林中，入侵灌木丛已成为一个紧急问题。它们的扩展叶片物候学（ELP）（与原生灌木和树冠相比，较早出现，后来脱落）可以同时为侵入性灌木提供光合作用，同时当树冠无叶时通过产生新颖的树荫来负面影响原生动植物。 。但是，物候学在地理上是不同的，并且尚不了解地方规模研究得出的ELP适用于所有经历灌木入侵的森林的程度。通过与美国国家物候网络的合作，我们开展了一项公民科学运动，以记录各种特定物种的ELP的广泛模式，而这本来是一项艰巨的努力。使用4年中对14种物种的1500次观测，我们发现，在生长季节内，天然灌木和入侵灌木之间的叶片物候差异可能超过77天，随着春季每度纬度增加2.9 [1.6，4.2]天以及2.2 [0.6，1.9 ]在秋天。ELP的地理趋势为解释当地规模的物候学研究提供了一个背景，同时弥合了现有研究之间不一致的发现，并且可以通过针对本地人处于休眠状态的入侵灌木进行检测和清除来简化管理。此外，即使季节物候变化很小，也会影响森林群落，尤其是当诞生对气候线索的反应不同时。在探索了与叶片物候相关的广泛环境变量之后，