Plant mixture balances terrestrial ecosystem C:N:P stoichiometry

Area of Science:

• Ecology
• Biogeochemistry
• Environmental Science

Background:

• Terrestrial ecosystem productivity, food webs, and nutrient cycling are critically influenced by plant and soil carbon:nitrogen:phosphorus (C:N:P) ratios.
• Global plant diversity is declining, yet its impact on ecosystem C:N:P ratios remains unclear.

Purpose of the Study:

• To investigate the influence of plant species mixtures and richness on terrestrial C:N:P ratios.
• To determine how plant diversity affects plant, soil, microbial, and enzyme stoichiometry.
• To understand the role of functional diversity in mediating the effects of species mixtures on ecosystem stoichiometry.

Main Methods:

• A global meta-analysis of 2049 paired observations comparing plant species mixtures and monocultures across 169 sites.
• Analysis of C:N:P ratios in plants, soils, soil microbial biomass, and soil enzymes.
• Examination of the relationship between functional diversity and mixture effects on stoichiometry.

Main Results:

• On average, plant and soil C:N:P ratios, microbial biomass, and enzymes did not significantly change with species mixture or richness.
• The effect of species mixtures on soil microbial biomass C:N shifted from positive to negative with increasing functional diversity.
• Species mixtures adjusted plant and soil C:N:P ratios, increasing them when background ratios were low and decreasing them when high.

Conclusions:

• Plant species mixtures can balance terrestrial ecosystem C:N:P ratios, contingent upon background soil stoichiometry.
• Plant diversity conservation not only enhances productivity but also optimizes ecosystem stoichiometry, supporting current and future vegetation.
• Findings underscore the importance of plant diversity for maintaining ecosystem function and resilience.