J Plant Ecol ›› 2020, Vol. 13 ›› Issue (1): 114-121.DOI: 10.1093/jpe/rtz045

• Research Articles • Previous Articles     Next Articles

Stoichiometry of leaf carbon, nitrogen, and phosphorus along a geographic, climatic, and soil gradients in temperate desert of Hexi Corridor, northwest China

Ke Zhang1,2, Mengmeng Li1, Yongzhong Su3, * and Rong Yang3   

  1. 1 School of Material and Chemical Engineering, Zhengzhou University of Light Industry, Zhengzhou 450000, China, 2 Collaborative Innovation Center of Environmental Pollution Control and Ecological Restoration, Henan Province, Zhengzhou 450000, China, 3 Linze Inland River Basin Research Station, Northwest Institute of Eco-Environment and Resources, CAS/Key Laboratory of Eco-Hydrology in Inland River Basin, CAS, Lanzhou 730000, China
  • Received:2019-05-13 Revised:2019-09-03 Accepted:2019-10-15 Online:2019-11-20 Published:2020-02-01

Abstract:

Aims

Understanding the regional pattern of leaf stoichiometry and its contributing variables are of importance for predicting plant responses to global change and modelling the productivity and nutrient fluxes of ecosystems. In this study, we investigated leaf stoichiometry of plants that sampled from Hexi Corridor, a typical arid region in China, and tried to explore the contribution variables on leaf stoichiometry along the geographic, climatic, and soil gradients.

Methods

In August 2012, 70 sites in Hexi Corridor were investigated. Plant leaves and soils from five equivalent plots within each site were sampled. C, N, and P contents of leaf and soil were measured.

Important findings

Compared with leaf N and P contents in regional and global scales, leaf N content in Hexi Corridor was close to them with the value of 20.19 mg g-1, while leaf P content was lower than them with the value of 1.34 mg g-1. Overall, leaf N:P value in Hexi Corridor was 15.70. Individually, leaf N:P values of shrubs and herbs were 16.81 and 14.80, respectively. Scaling exponents for leaf N vs. P of overall and shrubs in Hexi Corridor were 1.29, higher than the scaling exponent of herbs (1.08). Leaf stoichiometry of shrubs and herbs did not show significant latitudinal and longitudinal patterns, meanwhile, it has no significant correlation with mean annual precipitation (MAP), mean annual temperature (MAT), and soil elements. However, only leaf stoichiometry of herbs has significant correlation with altitude and aridity degree. These results indicate that plants in Hexi Corridor are possibly co-limited by N and P, while shrubs are mainly limited by soil P and herbs are limited by soil N. Scaling relationship reveals that leaf N vs. P of herbs is isometric. With increasing altitude, the quadratic regression for leaf C and N contents and the linear regression for leaf P content of herbs reflect the difference responses of the three elements on the variation of MAT along the altitude and it could be explained by plant physiology hypothesis and biogeochemical hypotheses. With decreasing aridity, leaf N and N:P of herbs increased significantly, inferring that herbs growth would be limited by P increasingly and strengthening the increasing nitrogen availability with increasing precipitation. In conclusion, different altitude and aridity patterns for leaf stoichiometry of herbs and shrubs reveal the plastic survive strategies of different xerophytes in Hexi Corridor. Moreover, leaf stoichiometry of herbs in Hexi Corridor could be as indicator of the changing environment that caused by aridity.

Key words: leaf stoichiometry, shrubs, herbs, aridity, Hexi Corridor

摘要:

理解叶片化学计量的区域模式及其贡献变量对于预测植物对全球变化的反应以及对生态系统的生产力和养分通量建模具有重要意义。在本研究中,我们调查了在中国典型干旱地区河西走廊采样的植物叶片化学计量,并试图探究沿地理、气候和土壤梯度对叶片化学计量的贡献变量。2012年8月,对河西走廊的70个站点进行调查。在每个站点的五个等效样地中,对植物叶片和土壤进行采样。测定叶片和土壤的C、N和P含量。与区域和全球尺度上的叶片N和P含量相比,河西走廊的叶片N含量与之接近,为20.19 mg g-1,而叶片P含量则低于其值,为1.33 mg g-1。对于所有样本,河西走廊叶片N:P比值为15.70。就个体分组而言,灌木和草本的叶片N:P比值分别为16.81和14.80。河西走廊所有样本叶片和灌木叶片N:P的比例指数为1.29,高于草本叶片的比例指数(1.08)。灌木和草本的叶化学计量没有显著的纬度和经度格局。同时,其与年均降水量(MAP),年均温(MAT)和土壤元素也没有显著的相关性。但是,草本的叶片化学计量与海拔高度和干旱程度有显著的相关性。这些结果表明,河西走廊的植物可能受N和P的共同限制,灌木主要受土壤P的限制,而草本主要受土壤N的限制。比例指数关系表明,叶片的N:P比值变化是等距的。随海拔的升高,草本叶片C和N含量的二次回归以及叶片P含量的线性回归反映出三种元素对MAT随海拔高度变化的不同响应,可以用植物生理假说和生物地球化学假说解释。随着干旱程度的降低,草本叶片的N和N:P比值显着增加,这表明,草本植物生长受到的P限制逐渐增加,并且随着MAP的增加而增大N有效性。综上所述,不同海拔和干旱模式下的草本和灌木叶片化学计量揭示了河西走廊不同旱生植物的可塑性生存策略。此外,河西走廊中草本叶片的化学计量指标可以作为由干旱引起的环境变化的指标。

关键词: 叶片化学计量, 灌木, 草本, 干旱, 河西走廊