Characteristics of photosynthetic rates in different vegetation types at high-altitude in mountainous regions

• Published in: The Science of the total environment Vol. 907; p. 168071
• Main Authors: Zhai, Biying, Hu, Zhaoyong, Sun, Shouqin, Tang, Zishu, Wang, Genxu
• Format: Journal Article
• Language: English
• Published: Elsevier B.V 10.01.2024
• Subjects: altitude; Altitudinal gradient; carbon cycle; carbon dioxide; climate change; Environmental factors; equations; Montane forest; mountains; photosynthesis; Photosynthetic capacity; photosynthetically active radiation; Plant functional types; stomatal conductance; temperature; terrestrial ecosystems; variance; vegetation; Montane forest; Plant functional types; Environmental factors; Altitudinal gradient; Photosynthetic capacity
• ISSN: 0048-9697; 1879-1026; 1879-1026
• DOI: 10.1016/j.scitotenv.2023.168071

Mountains play an important role in the carbon cycle of the terrestrial ecosystem and are one of the most sensitive ecosystems to climate change. However, our current knowledge regarding the physiological responses of alpine plants to environmental changes remains limited due to the severe climatic conditions prevailing in these high-altitude regions. Therefore, this study quantified the variations in photosynthetic rates (An) and identified their driving factors of herbaceous plants, shrubs, and trees along an elevation gradient (2200 m asl to 3200 m asl) on Mount Gongga. Elevation emerged as a significant determinant of An, with a general increase observed, albeit followed by a decline above 3000 m asl. In high-altitude regions, trees displayed more significant fluctuations in An compared to herbaceous plants and shrubs. The lower levels of atmospheric carbon dioxide concentration (eCO2) and temperature (T) in high-altitude regions resulted in a 16 % increase in An for herbaceous plants, 60 % increase for shrubs, and 43 % increase for trees compared to the low-altitude areas. Structural equation modeling (SEM) analyses underscored the considerable impact of environmental factors on An. Notably, PAR, eCO2, and gs were identified as positive influencers, while other factors exerted negative effects. Our results further highlighted that trees were subject to greater constraints from multiple factors compared to herbs and shrubs, aligning with the outcomes of our variance analysis. In summary, our study presents a comprehensive assessment of vegetation responses to environmental factors along elevational gradients. The significance of An in plants at high altitude to external factors suggests the potential adaptability of alpine plants, and also indicates that changes in photosynthetic physiological functions at high altitude should be paid more attention to in the study of climate change. [Display omitted] •Quantify and analyze alpine plant responses to Mount Gongga's environmental changes.•This study reveals mechanisms causing photosynthesis fluctuations in high-altitude trees.•Studies high-altitude plants' increased photosynthesis rates.•Explored climate, soil, and leaf area impacts on highland vegetation.