Dominant Grasses, Not Subordinate Forbs, Sustain Ecosystem Multifunctionality Across Spatial Scales

Area of Science:

• Ecology
• Environmental Science
• Biodiversity Research

Background:

• Anthropogenic nitrogen (N) deposition alters grassland ecosystems.
• Plant functional composition shifts impact biodiversity and ecosystem functioning.
• Interactive effects on multifunctionality across scales are poorly understood.

Purpose of the Study:

• Investigate interactive effects of N deposition and plant functional group removal on grassland biodiversity and multifunctionality.
• Assess these effects across multiple spatial scales (α, β, γ).
• Clarify the roles of dominant functional groups and biodiversity in ecosystem functioning under nutrient enrichment.

Main Methods:

• Eight-year field experiment in a subalpine meadow.
• Combined plant functional group removal (dominant grasses, subordinate forbs) with N addition.
• Measured biodiversity and multifunctionality at plot (α) and assemblage (β, γ) scales.

Main Results:

• Grass removal reduced α- and γ-multifunctionality, linked to reduced α-component multifunctionality.
• Forb removal did not significantly affect multifunctionality across scales.
• Grass removal increased plant diversity; forb removal decreased it, especially under N addition.
• Multifunctionality was more strongly tied to grass-associated functions than plant diversity.
• N addition altered diversity responses but not multifunctionality responses.

Conclusions:

• Dominant grasses play a crucial role in maintaining grassland multifunctionality, even under nitrogen enrichment.
• Plant diversity changes did not directly predict multifunctionality; specific functional groups are key.
• Integrated conservation strategies are needed to protect both dominant and subordinate species for ecosystem health.