Geographic pattern and effects of climate and taxonomy on nonstructural carbohydrates of Artemisia species and their close relatives across northern China

Abstract

Nonstructural carbohydrates (NSCs) are the primary products of photosynthesis and have implications for determining the carbon (C) limitation under current environmental conditions and the impact of climate change on the C balance in ecosystems. Yet, heretofore little was known about how climate and taxonomy affect NSC at the regional or global scale. We explored geographic patterns and effects of climate and taxonomy on the NSC in the aboveground organs of Artemisia species and their close relatives from 65 sites across northern China. Hierarchical linear models (HLMs) showed that sugar concentration decreased with increasing altitude and that the response of NSC to the altitudinal gradient differed among species. NSC concentration was affected by climate of the warmest quarter rather than annual climate. Sugar and starch concentrations differed significantly among species. Within the NSC C pool, species identity explained more of the total variance of sugar C than that of starch C. Our results show that the NSC pattern at a large geographical scale differs from that at the local scale. As a temporary storage of C, NSCs appear to be a direct product of the photosynthetic process rather than to function as protectants against environmental stresses during the growing season at the regional scale. Therefore, different species, even among closely related taxa, may vary in their adaptation to environmental gradients via the physiological adjustment of NSCs at the regional scale.