Plot-level data of root biomass and variables derived thereof

Root biomass was sampled to a depth of 40 cm and separated into five depth layers in the Trait-based biodiversity experiment in Jena, Germany, in 2012 and 2014. This data file contains plot-level data of root biomass (averaged over the five depth layers) and calculated variables based on root biomass. A description of each variable is included on a separate sheet called ‘metadata’ in each file

species-specific root biomass per plot per layer in 2012 and 2014

Root biomass was sampled to a depth of 40 cm and separated into five depth layers in the Trait-based biodiversity experiment in Jena, Germany, in 2012 and 2014. This file contains root biomass per species per layer per plot per year. A description of each variable is included on a separate sheet called ‘metadata’ in each file

root biomass per plot per layer in 2012 and 2014

Root biomass was sampled to a depth of 40 cm and separated into five depth layers in the Trait-based biodiversity experiment in Jena, Germany, in 2012 and 2014. This file contains total root biomass per soil layer per plot per year. A description of each variable is included on a separate sheet called ‘metadata’ in the file

Below-ground complementarity effects in a grassland biodiversity experiment are related to deep-rooting species

Below-ground resource partitioning is often proposed as the underlying mechanism for the positive relationship between plant species richness and productivity. For example, if species have different root distributions, a mixture of plant species may be able to use the available resources more completely than the individual species in a monoculture. However, there is little experimental evidence for differentiation in vertical root distributions among species and its contribution to biodiversity effects. We determined species-specific root standing biomass over depth using molecular techniques (real-time qPCR) in a large grassland biodiversity experiment (one to eight plant species mixtures), in 2 years. Species-specific root biomass data were used to disentangle the effects of positive interactions between species (complementarity effects) and effects due to dominance of productive species (selection effects) on root biomass in mixtures. In a next step, these biodiversity effects were linked to the diversity of rooting depths and the averaged rooting depth of the community. Root biomass increased with species richness. This was mainly due to positive interactions (the complementarity effect), which increased with species richness below-ground. In contrast, the selection effect decreased with species richness. Although there was considerable variation in vertical root distribution between species in monocultures, the diversity of rooting strategies did not explain the complementarity effect. Rather, the abundance of deep-rooting species in mixtures (i.e. high community-weighted mean) was significantly related to the complementarity effect. Comparing the "predicted" root distribution (based on monocultures) to the actual distribution in mixtures, we found that mixtures rooted deeper than expected, but this did not better explain the complementarity effect. Synthesis. This study demonstrates that vertical root distributions of species provide only subtle evidence for resource partitioning. We found no evidence that functional diversity in vertical rooting patterns was important for the complementarity effect, in contrast to our expectation that the enhancement of productivity was due to resource partitioning. Alternatively, we found significant but weak relationships between the complementarity effect and deep-rooting communities, based on the community-weighted mean root distribution. This suggests that factors other than below-ground resource partitioning alone may drive the biodiversity-productivity relationship.</p

Data from: Belowground complementarity effects in a grassland biodiversity experiment are related to deep-rooting species

1. Belowground resource partitioning is often proposed as the underlying mechanism for the positive relationship between plant species richness and productivity. For example, if species have different root distributions, a mixture of plant species may be able to use the available resources more completely than the individual species in a monoculture. However, there is little experimental evidence for differentiation in vertical root distributions among species and its contribution to biodiversity effects. 2. We determined species-specific root standing biomass over depth using molecular techniques (real time-qPCR) in a large grassland biodiversity experiment (1-8 plant species mixtures), in two years. Species-specific root biomass data were used to disentangle the effects of positive interactions between species (complementarity effects) and effects due to dominance of productive species (selection effects) on root biomass in mixtures. In a next step, these biodiversity effects were linked to the diversity of rooting depths and the averaged rooting depth of the community. 3. Root biomass increased with species richness. This was mainly due to positive interactions (the complementarity effect), which increased with species richness belowground. In contrast, the selection effect decreased with species richness. Although there was considerable variation in vertical root distribution between species in monocultures, the diversity of rooting strategies did not explain the complementarity effect. Rather, the abundance of deep-rooting species in mixtures (i.e. high community weighted mean) was significantly related to the complementarity effect. Comparing the ‘predicted’ root distribution (based on monocultures) to the actual distribution in mixtures, we found that mixtures rooted deeper than expected, but this did not better explain the complementarity effect. 4. Synthesis: This study demonstrates that vertical root distributions of species provide only subtle evidence for resource partitioning. We found no evidence that functional diversity in vertical rooting patterns was important for the complementarity effect, in contrast to our expectation that the enhancement of productivity was due to resource partitioning. Alternatively, we found significant but weak relationships between the complementarity effect and deep-rooting communities, based on the community weighted mean root distribution. This suggests that factors other than belowground resource partitioning alone may drive the biodiversity-productivity relationship

Lost in diversity: the interactions between soil-borne fungi, biodiversity and plant productivity

There is consensus that plant species richness enhances plant productivity within natural grasslands, but the underlying drivers remain debated. Recently, differential accumulation of soil-borne fungal pathogens across the plant diversity gradient has been proposed as a cause of this pattern. However, the below-ground environment has generally been treated as a ‘black box’ in biodiversity experiments, leaving these fungi unidentified. Using next generation sequencing and pathogenicity assays, we analysed the community composition of root-associated fungi from a biodiversity experiment to examine if evidence exists for host specificity and negative density dependence in the interplay between soil-borne fungi, plant diversity and productivity. Plant species were colonised by distinct (pathogenic) fungal communities and isolated fungal species showed negative, species-specific effects on plant growth. Moreover, 57% of the pathogenic fungal operational taxonomic units (OTUs) recorded in plant monocultures were not detected in eight plant species plots, suggesting a loss of pathogenic OTUs with plant diversity. Our work provides strong evidence for host specificity and negative density-dependent effects of root-associated fungi on plant species in grasslands. Our work substantiates the hypothesis that fungal root pathogens are an important driver of biodiversity-ecosystem functioning relationships

Below-ground complementarity effects in a grassland biodiversity experiment are related to deep-rooting species

Below-ground resource partitioning is often proposed as the underlying mechanism for the positive relationship between plant species richness and productivity. For example, if species have different root distributions, a mixture of plant species may be able to use the available resources more completely than the individual species in a monoculture. However, there is little experimental evidence for differentiation in vertical root distributions among species and its contribution to biodiversity effects. We determined species-specific root standing biomass over depth using molecular techniques (real-time qPCR) in a large grassland biodiversity experiment (one to eight plant species mixtures), in 2 years. Species-specific root biomass data were used to disentangle the effects of positive interactions between species (complementarity effects) and effects due to dominance of productive species (selection effects) on root biomass in mixtures. In a next step, these biodiversity effects were linked to the diversity of rooting depths and the averaged rooting depth of the community. Root biomass increased with species richness. This was mainly due to positive interactions (the complementarity effect), which increased with species richness below-ground. In contrast, the selection effect decreased with species richness. Although there was considerable variation in vertical root distribution between species in monocultures, the diversity of rooting strategies did not explain the complementarity effect. Rather, the abundance of deep-rooting species in mixtures (i.e. high community-weighted mean) was significantly related to the complementarity effect. Comparing the "predicted" root distribution (based on monocultures) to the actual distribution in mixtures, we found that mixtures rooted deeper than expected, but this did not better explain the complementarity effect. Synthesis. This study demonstrates that vertical root distributions of species provide only subtle evidence for resource partitioning. We found no evidence that functional diversity in vertical rooting patterns was important for the complementarity effect, in contrast to our expectation that the enhancement of productivity was due to resource partitioning. Alternatively, we found significant but weak relationships between the complementarity effect and deep-rooting communities, based on the community-weighted mean root distribution. This suggests that factors other than below-ground resource partitioning alone may drive the biodiversity-productivity relationship.</p