中科院成都生物研究所高山生态学科组史长光、副研究员孙庚等人在青藏高原东部典型的高寒草甸采用开顶式温室模拟秋季气候变暖方式, 研究了4种典型的草本植物秋季枯萎过程中叶片及茎中叶绿素和N的动态变化过程以及根系中非结构性碳水化合物(TNC)的贮存量，同时跟踪观测了这些物种第二年的生长和物候变化。研究结果发表于近期的美国《公共科学图书馆—综合》上。该研究得到了国家自然科学基金项目的资助。

研究发现，在秋季增温背景下，多数植物在枯萎初期叶绿素分解进程延缓而在后期加快，并最终保持与未变暖相似的分解程度。但是，变暖使整个枯萎过程植物地上组织中的N浓度升高，光合产物的合成增加，进而导致晚秋和初春根系中的TNC贮存量显著增加。虽然目前的研究结果显示，在复杂的种间作用下，秋季TNC贮存的增加未显著改变植物种群来年的生长和物候，但是气候变暖潜在通过改变生长末期生态过程而影响来年植物群落生长和物候的机制值得深入研究。（来源：中国科学报 鲁捷）

Effects of Warming on Chlorophyll Degradation and Carbohydrate Accumulation of Alpine Herbaceous Species during Plant Senescence on the Tibetan Plateau

Abstract  Plant senescence is a critical life history process accompanied by chlorophyll degradation and has large implications for nutrient resorption and carbohydrate storage. Although photoperiod governs much of seasonal leaf senescence in many plant species, temperature has also been shown to modulate this process. Therefore, we hypothesized that climate warming would significantly impact the length of the plant growing season and ultimate productivity. To test this assumption, we measured the effects of simulated autumn climate warming paradigms on four native herbaceous species that represent distinct life forms of alpine meadow plants on the Tibetan Plateau. Conditions were simulated in open-top chambers (OTCs) and the effects on the degradation of chlorophyll, nitrogen (N) concentration in leaves and culms, total non-structural carbohydrate (TNC) in roots, growth and phenology were assessed during one year following treatment. The results showed that climate warming in autumn changed the senescence process only for perennials by slowing chlorophyll degradation at the beginning of senescence and accelerating it in the following phases. Warming also increased root TNC storage as a result of higher N concentrations retained in leaves; however, this effect was species dependent and did not alter the growing and flowering phenology in the following seasons. Our results indicated that autumn warming increases carbohydrate accumulation, not only by enhancing activities of photosynthetic enzymes (a mechanism proposed in previous studies), but also by affecting chlorophyll degradation and preferential allocation of resources to different plant compartments. The different responses to warming can be explained by inherently different growth and phenology patterns observed among the studied species. The results implied that warming leads to changes in the competitive balance among life forms, an effect that can subsequently shift vegetation distribution and species composition in communities.

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journal. pone.0107874&representation=PDF