北方典型荒漠及荒漠化地区植物叶片氮磷化学计量特征研究

区域尺度植物叶片氮磷元素的化学计量特征对于认识陆地生态系统空间格局变化规律、未来变化趋势的预测,以及对全球变化的响应具有重要意义.通过野外调查和文献整理,对中国北方典型荒漠及荒漠化地区214种植物叶片氮磷含量及化学计量比的分布特征及其与水热要素的相关关系进行了研究.结果表明,北方典型荒漠及荒漠化地区214种植物叶片N含量的平均值为(24.45±8.1)mg/g,P含量的平均值为(1.74±0.88)mg/g,氮磷比平均值15.77±7.5.与全球、全国以及区域尺度的研究结果相比,这些区域植物具有相对较高的叶片N和P含量,但是叶片N/P无显著差异,具有保守性的特点.北方典型荒漠及荒漠化地区不同生活型植物叶片N、P含量N/P之间存在显著差异,灌木植物和非禾本科植物具有相对较高的N含量,非禾本科植物具有相对较高的P含量,灌木植物具有相对较高的氮磷比,说明不同生活型植物具有不同的养分利用策略.北方典型荒漠及荒漠化地区不同研究区植物叶片N含量无显著差异,但P和N/P含量差异显著.科尔沁沙地和毛乌素沙地植物叶片P含量较高.塔里木盆地、准噶尔盆地以及阿拉善高原的大部分植物叶片N/P16,科尔沁沙地的大部分植物叶片N/P14,说明不同研究区的土壤养分有效性存在差异.北方典型荒漠及荒漠化地区植物叶片N、P含量以及N/P与各研究区年平均温度没有明确相关性,但多年平均降水与叶片P含量以及N/P分别呈显著正相关和负相关关系.

Leaf Nitrogen and Phosphorus Stoichiometry in Typical Desert and Desertified Regions, North China

Characteristics of leaf nitrogen and phosphorus stoichiometry at regional scale is key factors to understand spatial pattern, forecast change trends and reveal responses of terrestrial ecosystem to global change. In this study, pattern of leaf nitrogen and phosphorus of 214 plants was investigated to elucidate their relationships with rainfall and temperature in typical desert and desertified regions of northern China. The results showed that average leaf nitrogen concentration, average leaf phosphorus concentrations, and leaf N/P of 214 species are (24.45 +/- 8.1) mg/g, (1.74 +/- 0. 88) mg/g, 15.77 +/- 7.5 in these regions of northern China, respectively. Compared with other studies at global, national or regional scale, leaf nitrogen and phosphorus concentrations are significantly higher in this study (p < 0.001). However, leaf N/P didn't show any significant differences with other studies. This implies that leaf N/P is generally well-constrained. One-way ANOVA analysis showed that leaf N, P, and N/P varied significantly among trees, shrubs, graminoids, and forbs. Leaf N concentration in shrubs, forbs and leaf P concentration in forbs are averagely higher than those in other life-forms, respectively. This implies that nutrient use strategies are significantly different among plant life-forms. There are no significant differences in leaf nitrogen concentration among each typically desert and desertified region. However, Leaf phosphorus concentration and leaf N/P are significantly different among each typically desert and desertified regions. Leaf phosphorus concentrations are relatively high in Kerqin Sand Land and Mowuso Sand Land. Leaf N/P of most species in Talimu basin, Zhunger Basin, and Alashan is higher than 16, and lower than 14 of most species in Kerqin Sand land. This means that nutrient constraining in different regions varies greatly. Correlations analysis showed that leaf N, P, and N/P are significantly correlated with annual precipitation, but not significantly correlated with annual mean temperature in desert and desertified regions of northern China.