Altitude‐dependent variation in leaf structure and pigment content provides the performance of a relict shrub in mountains of Mongolia.

Mountain climate and vegetation change rapidly with altitude therefore many plant species may be found within a narrow elevation range. In the mountains of northern Mongolia, a relict shrub Prunus sibirica L. occurs within restricted upland areas. We studied 25 whole‐plant and leaf traits of P. sibirica at 10 locations in the Khentei Mountains. A comparison with a global trait variation of terrestrial plants and a path model of apricot data measured were used to evaluate the pattern of functional response to altitude. The intraspecific variation of pigment content found in Siberian apricot was surprisingly comparable to the ranges of interspecific variation among terrestrial plants over a global scale. Increasing altitude caused a dramatic increase in both chlorophylls and chlorophyll/carotenoid ratio and a decrease in the chlorophyll a/b. We also found a decrease in leaf thickness contributed to transpiration and water use efficiency. Photosynthetic capacity and kinetics, plant sizes and biomass were not affected by altitude. The path modelling revealed that pigment content and leaf structure were two independent ways to maintain the plant carbon and water balance. Our results identify the important role of intraspecific variation in leaf pigments and structure in plant response to altitude. We propose that these leaf traits could be used as predictors for the species altitudinal limits. [ABSTRACT FROM AUTHOR]