Below‐ground resource partitioning alone cannot explain the biodiversity–ecosystem function relationship: A field test using multiple tracers

Abstract

1. Below-ground resource partitioning is among the most prominent hypotheses for driving the positive biodiversity-ecosystem function relationship. However, experimental tests of this hypothesis in biodiversity experiments are scarce, and the available evidence is not consistent.2. We tested the hypothesis that resource partitioning in space, in time or in both space and time combined drives the positive effect of diversity on both plant productivity and total community resource uptake. At the community level, we predicted that total community resource uptake and biomass production above-and below-ground will increase with increased species richness or functional group richness. We predicted that, at the species level, resource partition breadth will become narrower, and that overlap between the resource partitions of different species will become smaller with increasing species richness or functional group richness.3. We applied multiple resource tracers (Li and Rb as potassium analogues, the water isotopologues-H 2 18 O and 2 H 2 O, and 15 N) in three seasons at two depths across a species and functional group richness gradient at a grassland biodiversity experiment. We used this multidimensional resource tracer study to test if plant species partition resources with increasing plant diversity across space, time or both simultaneously.Additional Supporting Information may be found online in the supporting information tab for this article.How to cite this article: Jesch A, Barry KE, Ravenek JM, et al.Below-ground resource partitioning alone cannot explain the biodiversity-ecosystem function relationship: A field test using multiple tracers.

Weeds are not always evil: crop-weed relationships are context-dependent and cannot fully explain the positive effects of intercropping on yield

“…However, since weed performance was not affected by crop species number, the beneficial effects of crop species richness on yield does not seem to be due to a reduction in weed pressure. Rather, we suggest that other ecological processes must play a role in increasing crop productivity in diverse mixtures, such as nutrient partitioning, (Jensen, Carlsson, & Hauggaard-Nielsen, 2020; Von Felten et al, 2009), light partitioning (Jesch et al, 2018; Spehn et al, 2005), or changes in belowground microbial communities (Duchene, Vian, & Celette, 2017; Lange et al, 2015). We therefore think that higher crop productivity driven by these other factors enhances competition between crops and weeds and suppresses weeds, rather than the other way around.…”

Neighbouring plants modify maize root foraging for phosphorus: coupling nutrients and neighbours for improved nutrient‐use efficiency

“…However, any neighbours of maize represented potential competition, but neighbouring faba bean was less competitive than neighbouring maize (Zhang et al , ). Plants appear to minimize neighbour competition by directing assimilates to roots in soil away from the neighbouring plant, thereby enhancing root development in those zones and reducing competitive encounters (Figs , ) (Maina et al , ; Callaway et al , ; Jesch et al , ). Although the present study did not consider root locations in the vertical direction, because species tested used different depths in soil profile as part of their foraging strategy (Li et al , ), the results clearly indicated that once neighbouring maize or faba bean was present, greater root mass was distributed in the soil region away from the neighbouring plant in a horizontal direction, more so in maize/maize than in maize/faba bean treatments.…”

Linking ecology and plant pathology to unravel the importance of soil-borne fungal pathogens in species-rich grasslands

“…Although there is now consensus among ecologists that in general monocultures perform less well than plant species mixtures (Cardinale et al 2012), the main underlying mechanisms remain debated. On one hand, ecologists have focused on plant-plant interactions, with resource partitioning and facilitation between plants as the most likely explanations for the differential plant productivity (Jesch et al 2018;Mueller et al 2013;Ravenek et al 2014;Wright et al 2017). On the other hand, interactions between plants and pathogenic soil biota have emerged as an important mechanism for the positive biodiversity effect (de Kroon et al 2012;Maron et al 2011;Mommer et al 2018;Schnitzer et al 2011).…”