Department of Botany, Ecology and Plant Physiology, University of La Laguna (ULL), Apdo. 456, 38200, La Laguna, Tenerife, Spain.
Physiol Plant. 2020 Jun;169(2):228-243. doi: 10.1111/ppl.13069. Epub 2020 Feb 15.
High-mountain-ecosystems in the Mediterranean-type climate are exceptional because of their outstanding biodiversity but also because of their characteristic drought stress in summer. Still, plant functioning in these habitats has been largely understudied. Here, morphological, photochemical, and biochemical traits were seasonally assessed in six shrubs characterized by contrasting morphological traits, in the Teide mountain in the Canary Islands. Two adjacent populations, the first located in an open site and the second in the understorey of Pinus canariensis treeline forest, were evaluated. We aimed at disentangling (1) the role of morphological and biochemical photoprotective strategies and of their seasonal plasticity to cope with changing environmental conditions in this semiarid ecosystem, (2) how the interspecific differences in biochemical photoprotection are related to leaf morphology and phenology and (3) how living in the understory of the treeline may affect those responses. Our results indicate that both morphological and biochemical traits (particularly leaf habit, morphology and carotenoids from the β-branch) play an intricate role in photoprotection, and that a high interspecific variability exists. According to the down-regulation of photochemical activity and the upregulation of photoprotective molecules, species could be grouped into three types: (1) those more responsive to summer stress (e.g. Descurainia bourgeauana); (2) those more responsive to winter stress (e.g. Pterocephalus lasiospermus, Scrophularia glabrata and Adenocarpus viscosus); and (3) those showing rather constant behavior across seasons (e.g. Spartocytisus supranubius and Erysimum scoparium). In all the species, plants in the open site showed a marked seasonal physiological response in most of the studied parameters. Pinus canariensis canopy buffers environmental abiotic constrains. On a global change scenario, and provided further functional studies are needed, our results pinpoints heterogeneity in the sensitivity of these species against for instance late-frost or summer-heat/drought events, which could easily shift current species distribution in the coming years.
高山生态系统在具有地中海气候的地区是独特的，这不仅是因为它们拥有杰出的生物多样性，还因为它们在夏季会经历特征性的干旱胁迫。然而，这些生境中的植物功能仍在很大程度上未被研究。在这里，我们在特内里费岛的泰德火山对 6 种具有不同形态特征的灌木进行了季节性评估，这些灌木的形态特征各异，并且处于不同的生境中。两个相邻的种群，第一个位于开阔地，第二个位于针阔混交林林冠下，我们评估了它们的形态、光化学和生化特征。我们的目标是（1）在这个半干旱生态系统中，解析形态和生化光保护策略及其季节性可塑性在应对不断变化的环境条件中的作用；（2）种间生化光保护的差异与叶片形态和物候之间的关系；（3）生活在林冠下如何影响这些反应。我们的结果表明，形态和生化特征（特别是叶片习性、形态和来自β分支的类胡萝卜素）在光保护中起着复杂的作用，并且存在高度的种间变异性。根据光化学活性的下调和光保护分子的上调，物种可以分为三种类型：（1）对夏季胁迫更敏感的物种（例如，播娘蒿）；（2）对冬季胁迫更敏感的物种（例如，刺苍术、琉璃草和粘腺忍冬）；（3）在整个季节表现出相对稳定行为的物种（例如，长柄岩黄芪和欧洲菘蓝）。在所有物种中，开阔地的植物在大多数研究参数上表现出明显的季节性生理反应。西班牙栓皮栎树冠缓冲了环境非生物胁迫。在全球变化的情景下，并且需要进一步的功能研究，我们的结果指出了这些物种对例如晚霜或夏季高温/干旱事件的敏感性存在异质性，这可能会在未来几年内轻易改变它们的当前分布。
