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Resource Availability Alters Biodiversity Effects in Experimental Grass-Forb Mixtures
Alrun Siebenkäs1, Jens Schumacher2, Christiane Roscher3,4
1UFZ, Helmholtz Centre for Environmental Research, Department of Community Ecology, Theodor-Lieser-Strasse 4, 06120, Halle, Germany.
Plos One
|June 25, 2016
Summary
Plant diversity boosts grassland biomass, especially when nutrients are limited. Resource availability influences how different plant traits contribute to this diversity effect, highlighting the importance of functional composition.
Area of Science:
- Ecology
- Plant Community Ecology
- Ecosystem Functioning
Background:
- Positive diversity-productivity relationships are frequently observed, often attributed to resource complementarity.
- The influence of resource availability on the strength and mechanisms of diversity effects remains less understood.
- Functional traits and community composition are key factors potentially mediating these relationships.
Purpose of the Study:
- To investigate how light and nutrient availability affect aboveground biomass production in grassland plant communities.
- To determine the role of trait-independent complementarity effects (TICE) and dominance effects (DE) in driving net diversity effects (NE).
- To examine the influence of functional traits and community composition on diversity effects under varying resource conditions.
Main Methods:
- Experimental study using monocultures and mixtures of perennial grassland species (grasses, forbs; small, tall statures).
- Manipulation of light (shading) and nutrient (fertilization) availability.
- Measurement of aboveground biomass production and calculation of relative yield total (RYT), net diversity effects (NE), trait-independent complementarity effects (TICE), trait-dependent complementarity effects (TDCE), and dominance effects (DE).
Main Results:
- Mixtures showed higher productivity than monocultures (RYT>1) with positive net diversity effects (+34% biomass).
- Trait-independent complementarity effects (+21%) and dominance effects (+12%) were major contributors to net diversity effects.
- Fertilization decreased RYT and complementarity effects but increased dominance effects; shading had no significant impact on diversity effects.
Conclusions:
- Positive diversity effects in grassland communities are robust to changes in light availability but are modulated by nutrient levels.
- Resource conservation traits enhance complementarity, while tall growth and low leaf nitrogen diversity promote dominance effects.
- Complementary resource use is favored under conditions of lower nutrient availability, suggesting resource limitation enhances diversity effects.
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