Soil microbes regulate ecosystem productivity and maintain species diversity

Area of Science:

• Ecology
• Plant Biology
• Soil Microbiology

Background:

• Ecosystem productivity often increases with plant species diversity, a pattern typically explained by niche complementarity.
• Niche complementarity suggests diverse species utilize resources more efficiently, leading to higher productivity.
• An alternative hypothesis proposes soil microbes and density-dependent disease regulate this relationship.

Purpose of the Study:

• To investigate the mechanisms driving the asymptotic relationship between plant species diversity and ecosystem productivity.
• To differentiate the roles of niche complementarity and soil microbes in shaping the diversity-productivity pattern.

Main Methods:

• Conducted a series of field experiments manipulating plant species diversity.
• Assessed ecosystem productivity under conditions with and without soil microbes.
• Analyzed the influence of soil microbes and niche complementarity on plant growth and disease.

Main Results:

• The classic asymptotic diversity-productivity pattern was observed only in the presence of soil microbes.
• Soil microbes depressed plant growth at low diversity via density-dependent disease, creating the asymptotic pattern.
• Niche complementarity played a minor role, with high productivity at low diversity when soil microbes were absent.

Conclusions:

• Soil microbes, through density-dependent disease, are the primary drivers of the asymptotic diversity-productivity relationship.
• Species loss in ecosystems is likely to increase plant disease and reduce overall ecosystem productivity.
• Density-dependent disease may be a key mechanism linking plant species diversity maintenance and productivity.