Abstract:

Objective: To provide reference for tree species selection in Horqin sandy land, the distribution rules of nonstructural carbohydrate (NSC, including soluble sugars and starch in the study, accounting for more than 90% of the total) in main tree species of shelterbelt forests were studied, and the distribution patterns in NSC of different tree species were clarified. Method: The contents of soluble sugars and starch in different organs (leaves, branches, trunks and roots) of the main shelterbelt tree species (Pinus tabulaeformis, Pinus densiflora, Pinus sylvestris var. mongolica, Ulmus pumila and Populus×xiaozhuanica) in Horqin sandy land were measured. The two-way ANOVA was used to analyze the effects of tree species, organs and their interactions on NSC. One-way ANOVA was used to analyze the differences of soluble sugars, starch and NSC among different tree species, and the effects of the different leaf ages and branch ages on the distribution of NSC in conifers (P. tabulaeformis, P. densiflora and P. sylvestris var. mongolica). Result: There were no significant differences in the content of NSC in leaves among the five tree species. However, the soluble sugars contents in the branches and roots of coniferous species were significantly higher than those of broad-leaved tree species (U. pumila and P.×xiaozhuanica), while the values in the trunks were lower in coniferous species than those in broad-leaved tree species. The starch contents in leaves and branches of U. pumila were significantly higher than those of other tree species, while it was higher in roots of broad-leaved tree species than coniferous species. Meanwhile, the contents of soluble sugars and NSC were significantly greater in the leaves and branches than in the trunks and roots over the five tree species. The starch content was higher in the trunks of P. tabulaeformis and P. densiflora, but it was higher in the leaves of P. sylvestris var. mongolica, U. pumila and P.×xiaozhuanica. The contents of soluble sugars and NSC were higher in two-year-old than current year and one-year-old needles of P. tabulaeformis and P. densiflora, but the values were greater in one-year-old than current year and two-year-old needles of P. sylvestris var. mongolica. The starch content was the lowest in one-year-old needles among all age needles of P. tabulaeformis and P. densiflora, whereas it was the highest in one-year-old needles of P. sylvestris var. mongolica. The soluble sugars, starch and NSC contents decreased with increasing branch age of P. tabulaeformis and P. densiflora, while the soluble sugar content was greater in two-year-old than one-year-old branches of P. sylvestris var. mongolica. Conclusion: The results indicate that the NSC contents are relatively low in shelterbelt main tree species in Horqin sandy land. Soluble sugars allocate in different organs following nearer distance, and it is different in allocation pattern of starch in various organs of different tree species. NSC distribution in different organs is more beneficial for water absorption through roots for coniferous species, while it is more beneficial for water transport over long distances in stems for broad-leaved species. As for NSC distribution in different leaf ages of coniferous species, the one-year-old needles of P. sylvestris var. mongolica and the two-year-old needles of P. tabulaeformis and P. densiflora are the main organs. In different branch ages, NSC distribution decreases with increasing branch ages for P. tabulaeformis and P. densiflora, but one-year-old branches are distributed less for P. sylvestris var. mongolica.

Key words: soluble sugar, starch, nonstructural carbohydrate, allocation pattern, Horqin sandy land