Functional composition rather than species richness determines root characteristics of experimental grasslands grown at different light and nutrient availability
2016
Siebenkäs, Alrun | Roscher, Christiane
BACKGROUND AND AIMS: Results from many biodiversity experiments have established evidence for positive effects of diversity on aboveground plant productivity. However, less is known about the relationships between plant diversity and belowground plant community characteristics and their consistency at altered environmental conditions. METHODS: Monocultures, two- and four-species mixtures of two independent pools of four perennial temperate grassland species, each representing two functional groups (grasses, forbs) and two growth statures (tall, small), were grown in a field experiment at crossed levels of light and fertilization. Standing root biomass and root morphological traits were studied in the second year of treatment applications. RESULTS: Increased species richness or fertilization did not influence belowground characteristics. Shading decreased standing root biomass and affected root morphological characteristics. The vertical distribution of standing root biomass and root length density over the depth profile and root morphological traits differed in communities of varying functional composition irrespective of resource availability, and differences were partly increased when shading was combined with fertilization. CONCLUSIONS: Independent of resource availability, plant species richness does not increase vertical root segregation, but the potential for complementary use of belowground resources increases when species with different rooting patterns and root morphological traits are combined in mixtures.
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