Chondol Thinles, Gago Jorge, Flexas Jaume, Gulías Javier, Clemente-Moreno María José, Binter Jan, Doležal Jiří
Department of Functional Ecology, Institute of Botany, Czech Academy of Sciences, Třeboň, Czechia.
Department of Botany, Faculty of Science, University of South Bohemia, České Budějovice, Czechia.
Physiol Plant. 2025 May-Jun;177(3):e70269. doi: 10.1111/ppl.70269.
Plants in extreme environments face pronounced seasonal variations in abiotic conditions, influencing their growth and carbon gain. However, our understanding of how plants in cold-arid mountains sustain carbon assimilation during short growing seasons remains limited. Here, we investigate seasonal dynamics and interspecific variability in photochemical performance of 310 individuals, comprising 10 different dicotyledon plant species across 3100-5300 m in the NW Himalayas, spanning semi-deserts to subnival zones. From early June to late September, we measured F/F and ΦPSII, assessing ΦPSII relationships with leaf traits (N, P, C, C:N ratio, LMA, and LDMC) and environmental factors (temperature, soil moisture content, etc.). Our findings revealed that high-Himalayan plants maintained relatively stable photosynthetic performance (F/F = 0.7-0.85), indicating optimal function even under potential stress. Contrary to our hypothesis that ΦPSII peaks mid-season in alpine and subnival zones and early season in steppes and semi-deserts, it declined by 33% across species and habitats throughout the season. This decline was closely associated with nutrient depletion, leaf senescence, and energy-water limitations. Species exhibited distinct strategies, with some prioritising structural resilience over photosynthesis, while others optimised photochemical performance despite environmental constraints. Alpine and subnival plant performance was constrained more by soil moisture deficits and high temperatures than cold temperatures, while deep-rooted steppe and semi-desert plants were primarily constrained by high temperatures and evaporative forcing rather than soil moisture deficit. These results provide new insights into how Himalayan plants adapt to extreme environmental conditions, highlighting the crucial interplay between moisture and temperature in shaping their performance within cold-arid mountains.
处于极端环境中的植物面临着非生物条件下明显的季节性变化，这会影响它们的生长和碳获取。然而，我们对于寒冷干旱山区的植物如何在短暂的生长季节维持碳同化的理解仍然有限。在此，我们调查了310株个体的光化学性能的季节性动态和种间变异性，这些个体包括喜马拉雅西北部海拔3100 - 5300米处的10种不同双子叶植物物种，涵盖了从半荒漠到亚雪线地带。从6月初到9月末，我们测量了F/F和ΦPSII，评估了ΦPSII与叶片性状（氮、磷、碳、碳氮比、叶面积质量和叶干物质含量）以及环境因素（温度﹑土壤含水量等）之间的关系。我们的研究结果表明，高喜马拉雅地区的植物维持了相对稳定的光合性能（F/F = 0.7 - 0.85），这表明即使在潜在胁迫下其功能仍处于最佳状态。与我们的假设相反，即ΦPSII在高山和亚雪线地带的季节中期达到峰值，在草原和半荒漠地带的季节早期达到峰值，实际上它在整个季节中跨物种和栖息地下降了33%。这种下降与养分消耗、叶片衰老以及能量 - 水分限制密切相关。物种表现出不同的策略，一些物种将结构弹性置于光合作用之上，而另一些物种尽管面临环境限制仍优化光化学性能。高山和亚雪线植物的性能更多地受到土壤水分亏缺和高温的限制，而非低温，而深根的草原和半荒漠植物主要受到高温和蒸发胁迫的限制，而非土壤水分亏缺。这些结果为喜马拉雅植物如何适应极端环境条件提供了新的见解，突出了水分和温度在塑造其在寒冷干旱山区性能方面的关键相互作用。
