干旱林线区不同树种非结构性碳水化合物的季节格局及其主导因子

为探究干旱林线区不同树种非结构性碳水化合物(NSC)的季节格局以及生物因素(树种)和非生物因素(气候)在其中的作用, 选取内蒙古高原东南缘4种典型乔木(樟子松、白桦、小叶杨和华北落叶松)作为研究对象, 对其生长季叶片、树干中的可溶性糖、淀粉及总非结构性碳水化合物的浓度进行比较。结果表明: 不同功能型树种NSC各组分浓度具有相似的季节格局(生长季初期短暂上升, 生长季旺期持续下降, 生长季末期由于生长减缓而逐渐回升), 说明气候因素在NSC季节动态中起主导作用。不同树种 NSC 季节均值总体上具有显著差异(p<0.05), 白桦NSC各组分含量均高于樟子松, 体现生物因素的影响。更加干旱的局地气候条件使得樟子松NSC含量高于小叶杨及华北落叶松, 说明干旱林线NSC含量影响因子的复杂性。叶片可溶性糖及TNC含量高于树干, 而淀粉含量低于树干, 这与植物不同器官的功能差异有关。

Seasonal Patterns and Their Determinants of Non-structuralCarbohydrates in Different Tree Species at Xeric Timberline

To examine the seasonal patterns of non-structural carbohydrates (NSC) in different tree species andthe roles of biotic (tree species) and abiotic (climate) factors on these patterns at xeric timberline, the authorsmonitored seasonal patterns of non-structural carbohydrates in four different tree species (Pinus sylvestris var.mongolica, Betula platyphylla, Populus simonii and Larix principis-rupprechtii) in southeastern Inner MongolianPlateau of China. The results show that tree species with different foliar habit types have broadly similar seasonalnon-structural carbohydrates (NSC) patterns (NSC concentration increased at the beginning of the growing season,and reduced in summer because of high growth rate, then increased slowly in the end), which suggests a climaticdetermination. Significant differences (p<0.05) in NSC concentrations are observed between four tree species.NSC concentration in birch is significant higher than that in pine, reproducing the pattern that deciduous specieshave higher NSC pool than ever green ones, which suggests a biotic determination. Due to the relatively drierclimates, NSC concentration in larch and poplar turn to be lower than that in pine, implying a combined effect ofboth biotic and abiotic factors. The sugar and TNC (total non-structural carbohydrates) concentrations in leaf aresignificantly higher than those in stem, but the starch concentration in leaf is lower, which is consistent with thedifferent roles of leaf and stem.