A warmer world could extend the growing seasons for plants. Changes in spring phenology have been studied, yet autumn phenology remains poorly understood. Using >500,000 phenological records of four temperate tree species between 1951 and 2013 in Europe, we show that leaf senescence in warm autumns exhibits stronger climate responses, with a higher phenological plasticity, than in cold autumns, indicating a nonlinear response to climate. The onset of leaf senescence in warm autumns was delayed due to the stronger climate response, primarily caused by night-time warming. However, daytime warming, especially during warm autumns, imposes a drought stress which advances leaf senescence. This may counteract the extension of growing season under global warming. These findings provide guidance for more reliable predictions of plant phenology and biosphere–atmosphere feedbacks in the context of global warming.

世界变暖可能会延长植物的生长季节。已经研究了春季物候的变化，但对秋季物候的了解仍然很少。根据欧洲1951年至2013年间四种温带树种的500,000多个物候记录，我们发现，与寒冷的秋季相比，温暖的秋天的叶片衰老表现出更强的气候响应和更高的物候可塑性，表明对气候的非线性响应。由于较强的气候响应（主要是夜间升温），推迟了温暖的秋天叶片衰老的开始。但是，白天变暖，特别是在温暖的秋天，会造成干旱胁迫，从而加剧叶片衰老。在全球变暖的情况下，这可能抵消了生长期的延长。