塔里木河上游荒漠区4种灌木植物叶片与土壤生态化学计量特征

分析了塔里木河上游荒漠区灌木植物叶片和土壤碳(C)、氮(N)、磷(P)含量及其化学计量特征以及二者之间的相关性,旨在阐明荒漠植被在极端环境下养分循环及限制状况,为塔里木河上游荒漠生态系统的恢复与保护提供理论依据。以塔里木河上游多枝柽柳(Tamarix ramosissma)、盐穗木(Halostachys caspica)、黑果枸杞(Lycium ruthenicum)、铃铛刺(Halimodendron halodendron)4种荒漠灌木植物叶片和土壤为研究对象,分析植物叶片和土壤C、N、P生态化学计量特征及其相关性。结果表明:在4种不同荒漠灌木植物叶片中柽柳叶片的C含量为(484.77±59.74)mg/g,显著高于其他灌木植物(P0.05);铃铛刺的N含量是(14.20±1.58)mg/g,显著高于其他灌木植物(P0.05);柽柳叶片的P含量为(0.54±0.16)mg/g,显著低于其他灌木植物(P0.05)。4种灌木植物叶片C/N比值大小为黑果枸杞柽柳铃铛刺盐穗木,且黑果枸杞的C/N比值显著最高为(37.83±7.74)(P0.05);C/P为柽柳铃铛刺盐穗木黑果枸杞,盐穗木和黑果枸杞的C/P显著低于其他灌木(P0.05),其比值分别为(379.76±158.63)和(383.47±128.95);N/P为柽柳铃铛刺盐穗木黑果枸杞,柽柳的N/P比值显著最高为(22.34±4.60)(P0.05)。4种不同荒漠灌木土壤的有机碳(SOC)、全氮(TN)、全磷(TP)含量及其化学计量比特征均未表现出显著的差异。由相关性分析可知柽柳叶片仅P含量与土壤TP含量呈现出显著正相关(P0.05);铃铛刺叶片C含量与土壤TN、叶片P含量与土壤TN/TP均呈显著负相关(P0.05),而叶片C含量与土壤TN/TP呈极显著负相关(P0.01);盐穗木和黑果枸杞叶片化学计量特征与土壤的化学计量特征均未表现出显著相关性(P0.05)。说明植物叶片化学计量特征并非是由土壤养分含量特征直接决定的,更多受植物自身遗传特性的影响,体现了荒漠灌木植物对极端生境的适应性。

Stoichiometry characteristics of leaves and soil of four shrubs in the upper reaches of the Tarim River Desert

The main purpose of this study was to determine the concentration and the stoichiometric ratios of carbon (C), nitrogen (N), and phosphorus (P) in the leaves of four shrubs and the soil in the upper reaches of the Tarim River Desert. The correlation of C, N, and P stoichiometric ratios between leaves and soils was discussed. Results revealed the adaptation mechanism of desert vegetation to extreme environments and the limiting conditions of soil nutrients and provided scientific reference for restoration and protection of desert ecosystems in the upper reaches of the Tarim River. Four desert shrub species were used as plant materials. Leaf and soil samples were collected by ground acquisition method and quartation method, respectively, in August 2015. The C, N, and P concentrations in plant leaves and soils, stoichiometric ratios, and their correlations were calculated. The results showed that leaf C concentration was (484.77±59.74) mg/g, which was significantly higher in Tamarix ramosissima than in other three shrubs. The leaf N concentration was (14.20±1.58) mg/g, which was significantly higher in Halimodendron halodendron than in other shrubs, whereas the leaf P concentration in T. ramosissima was (0.54±0.16) mg/g, which was significantly lower than that of other shrubs. The C/N ratio in the leaves was ranked in the order of Lycium ruthenicum > T. ramosissima > H. halodendron > H. caspica,and the C/N ratio in H. caspica was (37.83±7.74), which was significantly higher than that of other shrubs (P < 0.05). The C/P ratio was ranked in the order of T. ramosissima > H. halodendron > L. ruthenicum > H. caspica, and the C/P ratio in L. ruthenicum and H. caspica was (379.76±158.63) and (383.47±128.95), respectively, which was significantly lower than those of the other shrubs. The N/P ratio was T. ramosissima > H. halodendron > H. caspica > L. ruthenicum, and the N/P ratio of T. ramosissima was (22.34±4.60), which was significantly higher than that of the other shrubs. The concentration and stoichiometric ratio of organic carbon (SOC), total nitrogen (TN), and total phosphorus (TP) showed no differences among soils for the four shrubs, and there was no significant difference among SOC, TN, and TP contents in soils (P > 0.05). The concentration of P in T. ramosissima leaves was positively correlated with soil TP concentration (P < 0.05). C concentration and TN concentration in H. halodendron leaves were negatively correlated with P and the TN/TP ratio (P < 0.05). C concentration in leaves was highly negatively correlated with the soil TN/TP ratio (P < 0.01), whereas in H. caspica and L. ruthenicum, there were no significant correlations between leaf and soil values (P > 0.05). There were significant differences in C, N, and P stoichiometric characteristics of the leaves of the four shrubs. The use efficiency of nutrient resources was also different in the plants species. The stoichiometric characteristics of C, N, and P were not significantly different in the four soils for the shrubs, which indicated that the habitat nutrient conditions of the four desert plants were not significantly different. There was no correlation in stoichiometric characteristics between shrub leaves and soil, and it was demonstrated that leaf stoichiometric characteristics were not directly determined by soil nutrient conditions, but affected by heritable characteristics of plants, which reflected the long-term adaptive characteristics of desert shrub plants for extreme habitat environments.