Abstract: Non-structural carbohydrates (NSC) are plant nutrients that not only supply carbon sources during environmental stress, but also reflect the adaptive strategies of plants to external conditions. Chenopodioideae plants are among the most species-rich and widely distributed flora in Central Asia deserts, playing an indispensable role in maintaining ecosystem stability. Current understanding remains limited regarding NSC allocation and utilization strategies across organs and life forms of Chenopodioideae plants in arid Central Asia. This study examined variation in NSC and its components in leaves and stems of Chenopodioideae plants across life forms in northwestern China, and explored their relationships with environmental and driving factors. Results showed significantly higher total NSC concentration in leaves than stems across life forms, with marked variations in starch, soluble sugars, fructose, sucrose and sugar-starch ratios among life forms. Allometric relationships were observed in NSC and its components between organs, with stems exhibiting higher accumulation rates of soluble sugars, fructose, and sucrose than leaves. Climate predominantly influenced NSC variations across plant organs at the transect scale, whereas geographic and soil factors exerted stronger influences on NSC and its components in different organs of small trees. Structural equation modeling revealed that climate, plant organs, and life forms collectively regulate NSC concentration, while climate additionally influences NSC levels indirectly via soil mediation. These findings not only advance our understanding of survival strategies of Chenopodioideae plants in central Asia, but also establish a theoretical framework for deciphering desert plants' roles in carbon cycling.

Key words: Chenopodioideae plant, non-structural carbohydrate, life form, allometry, spatial variation, trade-off