Addition of multiple limiting resources reduces grassland diversity

Area of Science:

• Ecology
• Plant Ecology
• Biodiversity Research

Background:

• Niche dimensionality theory explains biodiversity by the number of limiting factors allowing species coexistence.
• Plant species compete for resources, and adding resources can reduce trade-offs, potentially lowering species coexistence.
• Multiple nutrient limitation is common in plants, suggesting fertilization might decrease diversity by reducing belowground niche dimensionality.

Purpose of the Study:

• To investigate the impact of nutrient addition on plant species diversity and niche dimensionality.
• To test the hypothesis that increased nutrient availability reduces niche dimensionality and subsequently lowers plant diversity.
• To determine if nutrient addition effects on diversity are independent of biomass production.

Main Methods:

• Conducted experiments across 45 grassland sites globally.
• Manipulated the number of limiting nutrients added to experimental plots.
• Analyzed the relationship between nutrient addition, plant biomass, niche dimensionality, and species diversity.

Main Results:

• Increased number of added limiting nutrients significantly decreased plant species diversity across sites.
• Nutrient addition reduced niche dimensionality, even when plant biomass was not nutrient-limited.
• Elevated resource supply led to increased productivity and compositional turnover alongside diversity loss.

Conclusions:

• Nutrient enrichment, specifically the addition of multiple limiting nutrients, is a driver of plant species diversity loss.
• Reduced niche dimensionality is a key mechanism through which resource enrichment diminishes biodiversity.
• Understanding niche dimensionality is crucial for predicting and mitigating diversity loss in response to global change factors like fertilization.