荒漠短命植物不同生长期化学计量特征与生境土壤因子关系分析

The Stoichiometric Characteristics of Desert Ephemeral Plants in Different Growth Periods and Its Association with Soil Factors

深入了解荒漠短命植物的化学计量特征,有助于更好地理解生境土壤因子与植物生存策略的关系。以古尔班通古特沙漠广泛分布的尖喙牻牛儿苗(Erodium oxyrrhynchum)、假狼紫草(Nonea caspica)、琉苞菊(Hyalea pulchella)、飘带果(Lactuca undulata)为植物材料,测定不同深度(0~5、5~10、10~15 cm)的土壤理化性质,野外原位多时段采样比较分析4种植物化学计量特征与土壤因子的动态变化及其耦合关系。结果表明:(1)4种短命植物碳(C)、氮(N)、磷(P)含量普遍较低,化学计量特征存在物种间差异,但在不同生长期内变化规律大致相似。N、P含量从幼苗期到结实期逐渐减少,而C含量则长期趋于稳定。整个生长期内,P、C∶P的变异幅度较大,相反,C、N∶P的变异幅度较小。4种植物在不同生长期的化学计量特征差异与生长期、植物种类存在显著相关性。(2)0~5 cm土层有机碳(SOC)、总氮(TN)、总磷(TP)含量最高,且随土层的加深逐渐减少。随着植物的生长,0~5 cm土层中SOC和TN含量呈明显增加的趋势,而TP含量却呈现抛物线状变化趋势。在植物不同生长期内,土壤TP含量稳定性最强,SOC、TN的变异性较强,较低的N含量及TN∶TP比显示出该区域土壤属于N素缺乏类型。3个土层土壤在不同生长期的化学计量特征差异受土层、生长期的影响显著。(3)4种植物与各层次土壤化学计量特征的相关性无一致规律。植物化学计量指标仅与0~10 cm土层SOC、SOC∶TP相关性较强,而大部分化学计量特征间未显示出相关性。上述结果说明植物化学计量特征并非全部由土壤养分特征直接决定,其明显的种间差异显示了植物自身遗传特性在土壤—植物计量特征耦合关系的重要性。

To explore the stoichiometric characteristics of desert ephemeral plants,and to better understand the relationship between habitat soil factors and plant survival strategies,4 widely distributed plant species(Erodium oxyrrhynchum,Nonea caspica,Hyalea pulchella,Lactuca undulata)were collected,and soil physical and chemical properties were measured at different depths(0-5,5-10,10-15 cm),and the dynamic change and coupling relationship between stoichiometric characteristics of 4 plants and soil factors were compared and analyzed through in-situ multi-period sampling in the field.The results showed that:(1)The carbon(C),nitrogen(N),and phosphorus(P)contents of the 4 ephemeral plants were generally low,and there were differences in stoichiometric characteristics among species,but the changes were roughly similar in different growth periods.The content of N and P gradually decreased from the seedling stage to the fruit setting stage,while the C content tended to be stable for a long time.During the whole growth period,the variation range of P and C∶P were larger,the variation range of C and N∶P were smaller.The differences in the stoichiometric characteristics of the 4 plants in different growth periods were significantly related to the growth period and plant species.(2)The content of soil organic carbon(SOC),total nitrogen(TN)and total phosphorus(TP)in the 0-5 cm soil layer were the highest respectively,and gradually decreased with the depth of the soil layer.With the growth of plants,the content of SOC and TN in the 0-5 cm soil showed an obvious increasing trend,while the content of TP showed a parabolic change trend.During different growth periods of plants,the stability of soil TP content was the strongest,and the variability of SOC and TN was strong respectively.The lower N content and TN∶TP ratio showed that the soil in the area belonged to the type of N deficiency.The differences in the stoichiometric characteristics of the 3 soil layers in different growth periods were significantly affected by the soil layers and growth periods.(3)There was no consistent law in the correlation of stoichiometric characteristics between plants and soils at each level.Plant stoichiometric indicators were only strongly correlated with SOC and SOC∶TP in the 0-10 cm soil,and most of the stoichiometric characteristics did not show correlation,indicating that the stoichiometric characteristics of plants were not directly determined by the characteristics of soil nutrient content.These results indicated that the stoichiometric characteristics of plants were not directly determined by soil nutrient characteristics,and the obvious interspecific differences indicated the importance of plant genetic characteristics in the coupling relationship of soil-plant stoichiometric characteristics.