Phylogenetic diversity and plant trait composition predict multiple ecosystem functions in green roofs

Area of Science:

• Ecology
• Environmental Science
• Urban Greening

Background:

• Extensive green roofs provide ecosystem services, influenced by plant selection and diversity.
• While species richness is a predictor, functional and phylogenetic community structure offer stronger mechanistic links to ecosystem services.

Purpose of the Study:

• To assess the relationship between plant community structure (traits, functional diversity, phylogenetic diversity) and green roof functions.
• To determine how these factors influence ecosystem multifunctionality in experimental polycultures.

Main Methods:

• Measured community-weighted trait values for four key functional traits (plant height, leaf area, specific leaf area, dry leaf matter content).
• Evaluated functional diversity and phylogenetic diversity in relation to ten green roof functions.
• Utilized experimental polycultures to study these relationships.

Main Results:

• Dominant plant functional traits significantly influenced substrate nitrate-N, substrate phosphorus, aboveground biomass, and ecosystem multifunctionality.
• Functional diversity alone enhanced substrate organic matter.
• Both functional/phylogenetic diversity and identity predicted canopy density and substrate cooling.

Conclusions:

• Distinct aspects of phylogenetic and functional diversity are major predictors of multiple green roof services.
• Careful selection of plant traits and polycultures is crucial for optimizing green roof functioning.
• This study provides evidence for trait-based and diversity-based approaches in green roof design.