云南普洱季风常绿阔叶林不同林层非结构性碳水化合物特征

Non-structural carbohydrates characteristics of different forest layers in monsoon broad-leaved evergreen forest in Pu'er,Yunnan Province,China

在聚类分析的基础上,研究云南普洱季风常绿阔叶林主要物种非结构性碳水化合物(NSC)及其组分浓度、分配和季节性动态在林冠层、亚冠层和林下层间的变化特征.结果表明:亚冠层中可溶性糖及NSC浓度最高,分别为3.9%和13.3%,可溶性糖淀粉比在林下层最低,为0.76,而淀粉浓度则在各林层间无显著性差异.3个林层的可溶性糖均主要分配在叶片中,淀粉和NSC主要分配在根中.亚冠层中叶片和树干的可溶性糖浓度显著高于林冠层和林下层,枝和根的可溶性糖浓度在3个林层间无显著性差异;叶片的淀粉浓度则随林层高度降低而增加,但根淀粉浓度则是在林下层最低,为10.7%,枝和树干的淀粉浓度在3个林层间无显著差异;叶片NSC浓度为林冠层(10.7%)显著低于亚冠层(12.3%)和林下层(12.0%),但根的NSC浓度在林下层中最低,为14.2%;林下层叶片、枝、树干中可溶性糖淀粉比值均最低,但根的可溶性糖淀粉比值最低值出现在林冠层(0.79).3个林层NSC及其组分均存在显著的季节性变化,可溶性糖及可溶性糖淀粉比均为雨季显著高于旱季,而淀粉和NSC浓度则均在旱季中较高.不同林层NSC及其组分浓度的差异反映了不同高度树种碳利用策略的差异,部分地解释了物种的共存机制.

Based on cluster analysis of species vertical stratification, the variations in concentration, allocation and seasonal dynamics of non-structural carbohydrates were investigated in amonsoon broad-leaved evergreen forest in Pu’er, Yunnan Province. The results showed that the concentrations of soluble sugar （3.9%） and nonstructural carbohydrates （NSC, 13.3%） were the highest in the sub-canopy. In contrast, the sugar/starch （0.76） of understory was the lowest. There was no significant difference in starch content among three forest layers. For all forest stories, the soluble sugar was mainly allocated to leaves and the roots had more starch and NSC. The soluble sugar contents in leaves and trunks of sub-canopy species were higher than canopy and understory species. There were no significant differences in soluble sugar content of twigs and roots among three different forest layers. The starch content of leaves increased with decreasing height of forest layers. In contrast, the lowest starch content （10.7%） of roots was in understory. There was no significant difference in starch content of twigs and trunks among three different forest layers. The NSC content of leaves was lower in canopy （10.7%） than that in sub-canopy （12.3%） and understory （12.0%）. The lowest NSC content of roots was in understory （14.2%）. The lowest sugar/starch of leaves, twigs, and trunks presented in understory, while the lowest sugar/starch of roots presented in canopy （0.79）. There were dramatic seasonal variations in concentrations and components of NSC. The concentration of soluble sugar and the sugar/starch were higher in the rainy season than that in the dry season. However, the concentration of starch and NSC were higher in the dry season than in the rainy season. The variations in concentration of NSC and its components among forest layers indicated that species with different heights varied in their utilization strategies of carbon, which partly explained species coexistence.