Aridity and reduced soil micronutrient availability in global drylands.

Area of Science:

• Environmental Science
• Soil Science
• Ecology

Background:

• Drylands cover over 40% of Earth's land surface and are expanding due to climate change.
• Metallic micronutrients (Cu, Fe, Mn, Zn) are vital for life and ecosystem functioning.
• Micronutrient bioavailability in drylands under varying aridity remains poorly understood globally.

Purpose of the Study:

• To investigate how soil micronutrient (Cu, Fe, Mn, Zn) total and available concentrations change along global aridity gradients.
• To determine the impact of increasing aridity on micronutrient bioavailability in dryland soils.
• To assess potential stoichiometric alterations in micronutrient availability.

Main Methods:

• Analysis of soil samples from 143 drylands across all continents (except Antarctica).
• Measurement of total and available concentrations of copper (Cu), iron (Fe), manganese (Mn), and zinc (Zn).
• Assessment of soil properties including pH and organic matter content in relation to aridity.

Main Results:

• Dryland soils globally exhibit lower total and available micronutrient concentrations than typical soils.
• Increasing aridity significantly reduces the availability of all studied micronutrients (Cu, Fe, Mn, Zn).
• Aridity indirectly lowers micronutrient availability by increasing soil pH and decreasing soil organic matter.
• The available iron to zinc (Fe:Zn) ratio declines exponentially with increasing aridity, indicating stoichiometric shifts.

Conclusions:

• Projected increases in aridity due to climate change will likely limit essential micronutrient availability in drylands worldwide.
• Reduced availability of iron (Fe) and zinc (Zn) poses a significant threat to organisms and ecosystem services, including food production.
• Combined effects of reduced water and micronutrient availability may severely impact dryland ecological processes.