Global engineering effects of soil invertebrates on ecosystem functions

Area of Science:

• Ecology
• Soil Science
• Biogeochemistry

Background:

• Biogenic structures created by termites, ants, and earthworms play crucial roles in ecosystems worldwide.
• The global drivers of soil engineering effects by these invertebrates remain largely uncharacterized.
• Understanding these drivers is essential for predicting ecosystem functions and biogeochemical cycles.

Purpose of the Study:

• To investigate the global-scale drivers of soil engineering effects by termites, ants, and earthworms.
• To quantify the impact of these invertebrates on soil properties, microbial communities, and plant biomass.
• To identify how environmental factors, such as temperature and primary productivity, modulate these effects.

Main Methods:

• A comprehensive meta-analysis synthesizing data from 1,047 studies across six continents, encompassing 12,975 observations.
• Comparison of soils with invertebrate activity against reference soils lacking significant bioturbation.
• Statistical analysis to determine the influence of environmental variables on invertebrate-mediated soil improvements.

Main Results:

• Termites, ants, and earthworms universally increase soil macronutrient content, respiration, and microbial/plant biomass.
• Termite and earthworm impacts on soil properties and plant biomass are positively correlated with mean annual temperature, peaking in tropical regions.
• Ants' effects on soil nutrients, plant biomass, and survival peak in low-productivity, mid-latitude ecosystems.

Conclusions:

• These soil-engineering invertebrates are vital regulators of global biogeochemical cycles and ecosystem functions.
• Termites and ants differentially enhance plant growth by addressing phosphorus limitation in the tropics and nitrogen limitation in temperate zones, respectively.
• Biogeochemical models require improved integration of invertebrate effects, particularly concerning carbon fluxes and nutrient cycling.