关键词: 非结构性碳水化合物, 植物器官, 协同作用, 坡向, 林草交错区

Abstract: To elucidate the variation patterns and coordinated effects of non-structural carbohydrate (NSC) and their components across tree species and organs, we investigated Quercus mongolica, Malus baccata, and Ulmus pumila on different slope aspects (north, northwest, south, southwest slope) in the forest-grassland ecotone of northern Hebei Province. We examined the contents of soluble sugar, starch, and NSC in fine roots, branches, and leaves across slope aspects, to reveal the intra- and inter-specific variations and their driving factors. The results showed that the NSC and its component contents in all organs of the three tree species exhibited inconsistent variation patterns across the slope aspects. The NSC content in all organs of Q. mongolica ranged from 26.52 to 83.98 mg·g^-1 across slope aspects, while it ranged from 54.17 to 91.56 mg·g^-1 for M. baccata and 28.94 to 152.78 mg·g^-1 for U. pumila. Across all organs of the three tree species, the leaves of U. pumila exhibited the highest content of NSC and components. In contrast, Q. mongolica displayed the lowest levels in all organs, with the exception of a relatively higher soluble sugar content in fine roots. Both slope aspect and tree species significantly influenced organ NSC content. The intra-specific variation coefficients of NSC in different organs were relatively small. The inter-specific variation coefficients showed no significant differences among organs. Significant coordinated relationships were observed in NSC component contents among organs. There were positive relations for soluble sugar content between fine roots and branches. The soluble sugar content and starch content between fine roots and leaves exhibited significantly negative correlation. Redundancy analysis indicated that soil water content and pH were the primary environmental factors influencing the contents of NSC and its components in fine roots, branches, and lea-ves of the three tree species. Q. mongolica and M. baccata exhibited conservative strategy, while U. pumila exhibited acquisitive strategy.

Key words: non-structural carbohydrate, plant organ, coordinated effect, slope aspect, forest-grass ecotone