[Response of non-structural carbohydrates in leaves of different life-form plants to altitude in secondary Betula platyphylla forests in mountainous area of northern Hebei, China].

内容摘要

We measured the contents of starch, soluble sugars, and non-starch carbohydrates (NSC) in leaves of 60 common plant species (trees, shrubs, and herbaceous plants) from Betula platyphylla secondary forests across an altitude gradient (950, 1150, 1350, 1550, and 1750 m) in the northern Hebei mountainous region and analyzed their relationships with environmental factors. The results showed that both trees and shrubs exhibited significantly higher soluble sugar and NSC contents than herbaceous plants, while the starch-to-soluble sugar ratio (SC/SSC) was significantly lower in woody species, indicating a tendency to maintain higher carbon storage levels. With increasing altitude, NSC contents in trees first decreased and then increased, shifting from carbon limitation to growth limitation as a response to environmental stress, demonstrating a flexible trade-off strategy between 'growth' and 'energy storage'. In contrast, NSC in shrubs and herbaceous plants increased significantly with altitude, dominated by growth limitation, reflecting a conservative strategy focused on carbon accumulation under low-temperature stress. The mixed-effects model revealed that altitude was the key driver of NSC variation, with interspecific differences being the primary source of leaf NSC variation. Redundancy analysis indicated that the first two principal components explained 87.6%, 79.9%, and 93.1% of the cumulative variance for trees, shrubs, and herbaceous plants, respectively. The main influencing factors were soil moisture and total nitrogen for trees; soil pH, available phosphorus, and mean temperature of the growing season for shrubs; and, mean temperature of the growing season, soil moisture, and pH for herbaceous plants. This study revealed the differential regulation of hydrothermal conditions and nutrient supply on carbon balance of different plant life forms, and clarified that life form is a key dimension to explain the diversity of plant adaptation strategies to altitude gradient. 本研究沿海拔梯度(950、1150、1350、1550、1750 m)测定冀北山地白桦次生林60种常见植物(乔木、灌木、草本植物)的叶片淀粉、可溶性糖及非结构性碳水化合物(NSC)含量,并分析其与环境因子的关系。结果表明: 乔木和灌木的可溶性糖和NSC含量均显著高于草本植物,淀粉和可溶性糖的比值(SC/SSC)显著低于草本植物,表明木本植物倾向于维持更高的碳储备水平。随海拔升高,乔木NSC呈现先降低后升高的变化趋势,由碳限制转变为生长限制主导,其根据环境压力在“生长”与“储能”之间采取灵活权衡的策略;而灌木和草本植物的NSC则随海拔升高显著上升,受生长限制主导,呈现出在低温胁迫下以碳积累为主的保守策略。混合效应模型表明,海拔是驱动NSC变异的关键因子,种间差异是解释叶片NSC变异的主要来源。冗余分析表明,前2轴对乔木、灌木和草本植物的累计解释率分别为87.6%、79.9%、93.1%。其中,乔木的主要影响因子为土壤含水率和全氮;灌木为土壤pH、有效磷和生长季平均温度;草本植物为生长季平均温度、土壤含水率和pH。本研究揭示了水热条件与养分供应对不同生活型植物碳平衡的差异化调控,明确了生活型是解释植物对海拔梯度适应策略多样性的关键维度。.