<p>Non-structural carbohydrates (NSCs) are key physiological traits for understanding plant carbon (C) allocation, growth and distribution, particularly in harsh alpine environments. While the role of NSCs in alpine treeline trees has been extensively examined to elucidate the C-growth relationship, alpine shrubline, situated beyond the treeline and exposed to more extreme low temperature regime, remains understudied. Owing to functional difference between shrubs and trees, shrubs may adopt distinct physiological strategies for growth, survival and NSCs allocation in cold environments. This study aims to quantify and investigate spatio-temporal variations in NSCs includingtotal soluble sugars (TSS), Starch, total non-structural carbohydrates (TSS+Starch) and TSS/Starch ratio in leaf, stem and root tissues of three dominant alpine shrubs viz. <i>Rhododendron anthopogon</i>, <i>Juniperus polycarpos</i> and <i>Caragana versicolor</i>, forming the shrubline in western Himalaya. The study was conducted at nine spatially distinct sites considering both the upper distribution limit and corresponding lower elevations. Our results demonstrate that alpine shrubs exhibit higher NSCs concentrations at their upper limits relative to lower elevations. Moreover, NSCs concentration was consistently lower during mid-growing season than at the early and late growing season. These findings suggest that alpine shrubs at their upper limits maintain sufficient C reserves, implying that growth is unlikely to be limited by C supply, but is, instead, constrained by sink limitation, likely driven by lower temperature conditions. Under future climate warming scenarios, rising temperature may stimulate the utilization of C reserve, thereby enhancing growth and potential expansion of these shrubs into the alpine meadows, altering species composition and diversity.</p> Graphical abstract <p></p>