作 者 ：张慧文,马剑英*,孙伟,陈发虎
期 刊 ：生态学报 2010年 30卷 21期 页码：5747~5758
Keywords:Picea schrenkiana var. tianschanica, leaf functional traits, altitude, ecological adaptation, soil factors,
摘 要 ：植物功能性状反映了植物对生长环境的响应和适应，将环境、植物个体和生态系统结构、过程与功能联系在一起。为阐明天山北坡1420—2300m天山云杉（Picea schrenkiana var. tianschanica）的叶片功能性状对环境的适应性变化，研究了天山云杉10种叶片功能性状的变化规律以及与土壤因子的关系。结果表明叶长宽比（LL/LW）、叶面积（LA）、气孔密度（SD）、单位干重的叶磷（LPC）和叶钾（LKC）含量沿海拔梯度呈上升趋势。单位干重的叶氮（LNC）含量、叶绿素含量（Chla+b）、叶片饱和含水量（LWC）、叶片干物质含量（LDMC）和比叶重（LMA）随海拔的升高呈现非线性变化，前3项在海拔约2100m处达到最大值，分别为（15.42±0.38）mg/g、（2.44±0.37）mg/g和（55.01±0.48）%，后两项在海拔约2100m处达到最小值，分别为（45180±628）mg/g、（252.33±3.60）g/m2。逐步回归分析结果显示，海拔梯度上影响LPC的主要土壤因子是土壤pH值和SWC，影响LNC、LKC、Chla+b、LDMC、LMA和LWC的主要土壤因子是TN，影响LA、SD和LL/LW的主要土壤因子是SWC，可见SWC和TN是天山云杉叶片功能特征沿海拔梯度变化的主要驱动因子。在优越的环境中植物叶片虽然具有较高的光合能力和较高的相对生长速率，但是对资源的利用能力往往较低，在2100m附近LNC、Chla+b、LA最大，LMA、LDMC最小，因此判断此海拔附近为天山云杉最适宜的生长范围。
Abstract:Plant functional traits, defined as morpho-physio-phenological traits which impact fitness indirectly via their effects on growth, reproduction and survival, the three components of individual performance, link environmental factors, individual plants and ecosystem structures, processes and functions. Variation in leaf functional traits is one of the important strategies that plants used to respond and adapt to changes in environmental conditions. The continuous distribution of P. schrenkiana var. tianschanica, one of the major tree species in northwestern Chinese alpine and sub-alpine forest, across a range of altitude may have resulted from the combined effects of water-heat conditions and pedological factors. We investigated changes in ratio of leaf length and width (LL/LW), leaf area (LA), stomatal density (SD), leaf nitrogen concentration per unit mass (LNC), leaf phosphorus concentration per unit mass (LPC), leaf potassium concentration per unit mass (LKC), pigment contents (Chla+b), leaf dry matter content (LDMC), leaf mass per unit area (LMA) and leaf saturated water content (LWC) in P. schrenkiana var. tianschanica along an altitudinal gradient (1420, 1505, 1622, 1757, 1850, 1962, 2045, 2110, 2240, 2300 m) on the northern slopes of the Tianshan Mountains in northwest China. The objectives were to understand adaptation of leaf functional traits to varying abiotic factors associated with changes in altitude and to identify the main soil factors driving variation in leaf functional traits along the altitudinal gradient. We used regression analysis to evaluate the relationships between elevation and leaf functional traits and stepwise regression analyses to determine the main soil factors that control variation in leaf functional traits. We observed that all the leaf functional traits differed significantly among different positions along the altitudinal gradient P<0.001). We also found that LL/LW, LA, SD, LPC, LKC increased linearly with increasing elevation, whereas LNC, Chla+b, LDMC, LMA and LWC varied non-linearly with changes in altitude. Below 2100 m, LNC, Chla+b and LWC increased, while LDMC and LMA decreased, significantly with increasing altitude. The maximum values of LNC (15.42±0.38) mg/g, Chla+b (244±0.37) mg/g and LWC (55.01±0.48) % and the minimum values of LDMC (451.80±628) mg/g, and LMA (252.33±3.60) g/m2 were obtained at an altitude of about 2100 m. Moreover, stepwise regression analysis between leaf functional traits and soil factors suggested that LPC was influenced primarily by pH and soil water content (SWC). LNC, LKC, Chla+b, LDMC, LMA and LWC were mainly influenced by soil total nitrogen (TN). LA, SD and LL/LW were influenced by SWC. TN and SWC were the main drivers of variation in the leaf functional traits in P. schrenkiana var. tianschanica along the altitudinal gradient. In their superior environment, plants have a relatively high photosynthetic rate and growth rate associated with greater LNC and chlorophyll contents and LA, respectively. However, high photosynthetic and relative growth rates are achieved under lower utilization of resources, which are indicated by low-LDMC and low-LMA. Based on the observed maximum values in LNC, Chla+b and LA and the minimum values in LMA and LDMC at the elevation of 2100 m, we concluded that the best growing elevation for P. schrenkiana var. tianschanica in the Tianshan Mountains was approximately 2100 m.
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