Plant Nutrient Contents Rather Than Physical Traits Are Coordinated Between Leaves and Roots in a Desert Shrubland

Xiaoyan Jiang; Xin Jia; Shengjie Gao; Yan Jiang; Ningning Wei; Cong Han; Tianshan Zha; Peng Liu; Yun Tian; Shugao Qin

doi:10.3389/fpls.2021.734775

Plant Nutrient Contents Rather Than Physical Traits Are Coordinated Between Leaves and Roots in a Desert Shrubland

Front Plant Sci. 2021 Oct 26:12:734775. doi: 10.3389/fpls.2021.734775. eCollection 2021.

Authors

Xiaoyan Jiang¹, Xin Jia^{1

2}, Shengjie Gao¹, Yan Jiang¹, Ningning Wei¹, Cong Han¹, Tianshan Zha^{1

2}, Peng Liu^{1

2}, Yun Tian², Shugao Qin^{1

2}

Affiliations

¹ Yanchi Research Station, School of Soil and Water Conservation, Beijing Forestry University, Beijing, China.
² Key Laboratory for Soil and Water Conservation, State Forestry and Grassland Administration, Beijing Forestry University, Beijing, China.

Abstract

Although leaf economics spectrum (LES) has been extensively tested with regional and global datasets, the correlation among functional traits of desert plants remains largely unclear. Moreover, examinations on whether and how leaf and root traits are coordinated have yielded mixed results. We investigated variations in leaf and fine-root traits across 48 species in a desert community of northern China to test the hypotheses that (1) the leaf-trait syndrome of plant species in desert shrublands follows the predictions of the global LES, and is paralleled by a similar root-trait syndrome, (2) functional traits related to nutrient contents and resource uptake are tightly coordinated between leaves and fine roots in desert ecosystems where plant growth is limited primarily by dry and nutrient-poor conditions, and (3) traits as well as their relationships vary among functional groups. Our results partially supported the LES theory. Specific leaf area (SLA) was correlated with leaf tissue density, phosphorus content, and carbon-to-nitrogen ratio, but not with leaf nitrogen content. Specific root length (SRL) was not correlated with other fine-root traits, and fine-root traits were largely independent of each other. Therefore, fine-root traits did not mirror the leaf-trait syndrome. Fine-root nitrogen and phosphorus contents, nitrogen-to-phosphorous ratio, and carbon-to-nitrogen ratio all increased with analogous leaf traits, whereas SRL was not correlated with SLA. After phylogenetic effects were considered, nutrient contents and their ratios still displayed stronger coordination between leaves and fine roots than did SRL and SLA. The overall pattern of trait variations and relationships suggested differentiation among functional groups. Our results suggest that despite the absence of a root-trait syndrome, fine-root functions in the studied desert community were probably coordinated with leaf functions with respect to nutrient allocation and use.

Keywords: functional trait; plant functional type; specific leaf area; specific root length; stoichiometry.