BACKGROUND AND AIMS: Understanding interspecific differences in plant growth rates and their internal and external drivers is key to predicting species responses to ongoing environmental changes. Annual growth rates vary among plants based on their ecological preferences, growth forms, ecophysiological adaptations and evolutionary history. However, the relative importance of these factors remains unclear, particularly in high-mountain ecosystems experiencing rapid changes. METHODS: We examined how habitat associations, elevational optima, growth forms, and ecophysiological and anatomical traits influence interspecific differences in radial growth rates among 324 vascular dicot species naturally occurring in the western Himalayas. Growth rates were determined from annual ring width measurements on the oldest plant sections of over 7800 individuals from a range of habitats (desert, steppe, wetland, alpine, subnival), growth forms (perennial tap-rooted, rhizomatous, cushiony, woody) and climatic gradients (elevations of 2650-6150 m). KEY RESULTS: Habitat associations accounted for 24 % of the variability in interspecific growth rates. Adding growth form and height increased the explanation to 42 %, and incorporating plant functional traits further improved predictions to 46 %. Growth rates were higher in warmer, drier conditions and lower in cold, wet environments. Subnival cushion plants had the slowest growth, while ruderal plants grew the fastest. Desert plants showed higher growth rates, reflecting their drought adaptive strategies, while wetland forbs had lower growth rates due to increased resource competition. Growth was positively correlated with leaf nitrogen content and non-structural carbohydrates (mainly fructans), due to enhanced photosynthesis and stress tolerance, and negatively correlated with leaf carbon and root nitrogen content. CONCLUSION: Our study of 324 dicot species in the western Himalayas suggests that plant growth in high elevations is determined by a combination of habitat conditions, morphological traits and ecophysiological adaptations. Growth variations among the highest-growing angiosperms reflect adaptive strategies along the global 'fast-slow' and 'acquisitive-conservative' spectrums. These results underscore the importance of habitat-specific studies for predicting plant growth responses to environmental changes, emphasizing a species-specific approach for effective conservation in fragile ecosystems.

• Klíčová slova
• Fast–slow economics spectrum, Himalayan plants, ecophysiology, functional traits, herbchronology, high-elevation plants, plant growth,
• MeSH
• druhová specificita MeSH
• ekosystém * MeSH
• fyziologická adaptace * MeSH
• nadmořská výška MeSH
• Publikační typ
• časopisecké články MeSH
• Geografické názvy
• Indie MeSH

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 Fv/Fm 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 (Fv/Fm = 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.

• Klíčová slova
• Fv/Fm, Himalayas, alpine and subnival ecosystems, chlorophyll fluorescence, cold‐arid mountains, leaf traits, photochemical performance of PSII, seasonal dynamics,
• MeSH
• ekosystém MeSH
• fotosyntéza * fyziologie   MeSH
• listy rostlin fyziologie   MeSH
• nízká teplota MeSH
• půda chemie   MeSH
• roční období MeSH
• Publikační typ
• časopisecké články MeSH
• Geografické názvy
• Himálaj MeSH
• Názvy látek
• půda MeSH

Recent changes in water availability can be crucial for the development, growth and carbon budget of forests. Therefore, our aim was to determine the effect of reduced throughfall and severe summer drought on stem CO2 efflux as a function of temperature and stem increment. Stem CO2 efflux was measured using the chamber method on oak and hornbeam under four treatments: coppice, thinned coppice, and both coppice and thinned coppice with 30 %-reduced throughfall. The first year of the experiment had favourable soil water availability and the second year was characterized by a dry summer. While reduced throughfall had no effect on stem CO2 efflux, the summer drought decreased efflux by 43-81 % during July and August. The stem CO2 efflux was reduced less severely (by 13-40 %) in September when the drought persisted but the stem increment was already negligible. The stem increment was also strongly affected by the drought, which was reflected in its paired relationship with stem CO2 efflux over the two experimental years. The study showed that summer dry periods significantly and rapidly reduce stem CO2 efflux, whereas a constant 30 % rainfall reduction needs probably a longer time to affect stem properties, and indirectly stem CO2 efflux.

• Klíčová slova
• Carpinus betulus, Quercus petraea, soil water content, stem growth, stem respiration, summer drought,
• Publikační typ
• časopisecké články MeSH