Phenology differences between native and novel exotic-dominated grasslands rival the effects of climate change

1. Novel ecosystems can differ from the native systems they replaced. We used phenology measures to compare ecosystem functioning between novel exotic-dominated and native-dominated grasslands in the central US.

2. Phenology, or timing of biological events, is affected by climate and land use changes. We assessed how phenology shifts are being altered by exotic species dominance by comparing remotely sensed Normalized Difference Vegetation Index (NDVI) within growing seasons at exotic- and native-dominated sites along a latitudinal gradient. Exotic species were dominated by the C3 species functional group in the north and the C4 species functional group in the south.

3. Date of senescence was an average of 36 days later in exotic than native-dominated grasslands, and this effect was consistent across latitudes.

4. Exotic-dominated grasslands greened up an average of 10.7 days earlier than native-dominated grasslands, but this effect was highly dependent on latitude and the plan...

1. 新型生态系统（Novel ecosystems）与其所替代的原生生态系统存在显著差异。本研究以美国中部地区外来物种主导型与本土物种主导型草原为研究对象，通过物候学（Phenology）指标对比二者的生态系统功能。
2. 物候学，即生物事件的发生时序，受气候变化与土地利用变化的影响。本研究通过对比沿纬度梯度分布的外来主导型与本土主导型样地在生长季内的遥感归一化植被指数（Normalized Difference Vegetation Index，NDVI），评估了外来物种优势度对物候偏移的调控作用。北部地区的外来优势群落以C3物种功能群为主，南部则以C4物种功能群为主。
3. 外来物种主导的草原的枯黄衰老期平均较本土主导草原延后36天，且该效应在所有纬度梯度上均保持一致。
4. 外来物种主导的草原平均较本土主导草原早10.7天返青，但该效应在很大程度上依赖于纬度及[原文未完整呈现内容]。