High-resolution community-level sodium variation on the Tibetan Plateau: Content, density, and storage

Area of Science:

• Ecology
• Biogeochemistry
• Plant Physiology

Background:

• Sodium (Na) is a crucial mineral element for plant growth, primarily through osmotic adjustment.
• Previous research on Na content has been limited to individual plants or species, hindering ecosystem-level understanding.
• Characterizing Na at the community level is essential for linking its role to broader ecosystem functions.

Purpose of the Study:

• To comprehensively characterize community-level sodium (Na) content, density, and storage across the Tibetan Plateau (TP).
• To investigate the spatial variation of Na content and density in relation to environmental factors.
• To create a high-resolution spatial map of plant Na density on the TP.

Main Methods:

• Grid-plot sampling of various plant organs from 2040 natural plant communities on the TP.
• Analysis of Na content in leaves, branches, trunks, and roots.
• Application of a random forest algorithm to simulate and map spatial variations in Na density.

Main Results:

• Na content varied significantly across plant organs, with roots showing the highest concentration (0.71 mg g⁻¹).
• Higher Na content was observed in desert biomes, particularly under drought stress.
• Environmental factors like oxygen partial pressure, radiation, precipitation, soil Na supply, and temperature influenced spatial Na variation.
• A 1 km × 1 km spatial map revealed higher Na density in the southeastern TP.
• Total plant Na storage on the TP was estimated at 111.80 × 10⁴ tons.

Conclusions:

• This study provides the first large-scale characterization of community-level sodium on the Tibetan Plateau.
• Findings offer insights into plant community adaptation strategies and mineral element status.
• The generated spatial data is valuable for optimizing ecological models and understanding ecosystem functions.