Alpine plants have evolved a tight seasonal cycle of growth and senescence to cope with a short growing season. The potential growing season length (GSL) is increasing because of climate warming, possibly prolonging plant growth above- and belowground. We tested whether growth dynamics in typical alpine grassland are altered when the natural GSL (2–3 months) is experimentally advanced and thus, prolonged by 2–4 months. Additional summer months did not extend the growing period, as canopy browning started 34–41 days after the start of the season, even when GSL was more than doubled. Less than 10% of roots were produced during the added months, suggesting that root growth was as conservative as leaf growth. Few species showed a weak second greening under prolonged GSL, but not the dominant sedge. A longer growing season under future climate may therefore not extend growth in this widespread alpine community, but will foster species that follow a less strict phenology.

高山植物进化出了严格的生长和衰老季节周期，以应对较短的生长季节。由于气候变暖，潜在生长季长度（GSL）正在增加，可能会延长植物的地上和地下生长。我们测试了当自然 GSL（2-3 个月）通过实验提前并因此延长 2-4 个月时，典型高山草原的生长动态是否会发生改变。额外的夏季月份并没有延长生长期，因为树冠褐变是在季节开始后 34-41 天开始的，即使 GSL 增加了一倍多。在接下来的几个月里，只有不到 10% 的根产生了，这表明根的生长与叶子的生长一样保守。很少有物种在长时间的 GSL 下表现出微弱的二次绿化，但优势莎草却没有。因此，未来气候下更长的生长季节可能不会延长这个广泛的高山群落的生长，但会培育遵循不太严格的物候学的物种。