中国科学院青藏高原研究所罗天祥课题组发现，高寒草地广布优势物种普遍形成了一种能感应季风雨来临时间的物候适应策略。相关成果近日发表于《Scientific Reports》。 

　　青藏高原过去30年气温普遍升高且升温速率远高于全球平均值，但基于遥感数据的区域草地植被返青期表现为推迟、提前、没有变化等不同趋势。在青海5个站点近20年定位观测发现，高寒草甸优势物种的返青期无显著变化趋势，有关调控因子和机制仍不清楚，而这是理解气候变化响应的关键。 

　　该研究表明，嵩草属和针茅属等广布优势物种的返青期与季风雨来临时间同步，对降水变化敏感，但对温度变化不敏感；伴生的垫状植物返青期最早且在温暖年份提前，对温度变化敏感，但对降水变化不敏感。研究表明，在雨热同期的季风气候效应下，为避免春季低温和干旱胁迫，高寒草地广布优势物种普遍形成一种能感应季风雨来临时间的物候适应策略。这一新认识解释了青藏高原高寒草甸/草原的扇型分布格局以及返青物候和生产力的时空变化格局，并为理解季风气候变化及其影响范围、古植被演变及西风与季风交互作用等提供了理论基础。（来源：中国科学报 陆琦 彭科峰） 

　　Leaf unfolding of Tibetan alpine meadows captures the arrival of monsoon rainfall 

　　Abstract  The alpine meadow on the Tibetan Plateau is the highest and largest pasture in the world, and its formation and distribution are mainly controlled by Indian summer monsoon effects. However, little is known about how monsoon-related cues may trigger spring phenology of the vast alpine vegetation. Based on the 7-year observations with fenced and transplanted experiments across lower to upper limits of Kobresia meadows in the central plateau (4400–5200 m), we found that leaf unfolding dates of dominant sedge and grass species synchronized with monsoon onset, regardless of air temperature. We also found similar patterns in a 22-year data set from the northeast plateau. In the monsoon-related cues for leaf unfolding, the arrival of monsoon rainfall is crucial, while seasonal air temperatures are already continuously above 0 °C. In contrast, the early-emerging cushion species generally leafed out earlier in warmer years regardless of precipitation. Our data provide evidence that leaf unfolding of dominant species in the alpine meadows senses the arrival of monsoon-season rainfall. These findings also provide a basis for interpreting the spatially variable greening responses to warming detected in the world’s highest pasture, and suggest a phenological strategy for avoiding damages of pre-monsoon drought and frost to alpine plants.