Aboveground–belowground interactions as a source of complementarity effects in biodiversity experiments

Abstract

Background The positive relationship between biodiversity and ecosystem functioning (BEF) is due mainly to complementarity between species. Most BEF studies primarily focused on plant interactions; however, plants are embedded in a dense network of multitrophic interactions above and below the ground, which are likely to play a crucial role in BEF relationships. Scope In the present review I point out the relevance of aboveground-belowground interactions as a source of complementarity effects in grassland biodiversity experiments. A review of the current knowledge on the role of decomposers, arbuscular mycorrhizal fungi, rhizobia, plant growth promoting rhizobacteria, invertebrate ecosystem engineers, herbivores, pathogens and predators in biodiversity experiments, indicates that soil biota can drive both positive and negative complementarity between plant species via a multitude of mechanisms. Conclusions I pose four main processes by which aboveground-belowground interactions determine positive complementarity effects: enlarging biotope space, mediating legume effects, increasing plant community resistance, and maintaining plant diversity. By contrast, soil biota may also reinforce negative complementarity effects by competing with plants for nutrients or by exerting herbivore or pathogen pressure, thereby reducing community productivity. Thus, considering aboveground-belowground interactions as well as interactions between antagonistic and mutualistic consumers may improve the mechanistic understanding of complementarity effects in plant diversity-ecosystem functioning experiments and should inspire future research.

Soil Biology Research across Latitude, Elevation and Disturbance Gradients: A Review of Forest Studies from Puerto Rico during the Past 25 Years

“…The Santana et al [47] study published in 2005 was among the first to show that diversity of primary decomposers was related to ecosystem function, and that there is more complementarity and less redundancy in below-ground ecosystems than previously thought. A subsequent review by Eisenhauer [48], supports the theoretical basis for diversity effects on ecosystem function through complementarity in below-ground systems, whereas Bardgett and van der Putten [49] have argued that species richness only has effects in very simple systems because there is much redundancy. Most recently, analyses of European grasslands by Soliveres et al [50] showed that multitrophic diversity strongly predicted ecosystem functions, and that diversity of microbial decomposers has a particularly strong effect.…”

Plant: soil interactions in temperate multi-cropping production systems

“…Cultural management practices, such as multiple-cropping and crop rotations can offer a form of biological disease and pest control (Hao et al 2010). Crops, when grown in combination with other species, show less reduction in productivity and damage due to pest and disease incidence, than when grown as a sole crop (Trenbath 1993;Eisenhauer 2012). …”

“…Endo-and epi-phytic rhizobacteria, such as Herbaspirillum, but also AM fungi, can benefit a host plant by promoting plant growth via biological N fixation, nutrient solubilisation, synthesis of hormones and vitamins, by biological disease control, and via inducing systemic resistance (Altieri 1995c;Eisenhauer 2012;Monteiro et al 2012). In most cases, biological control results from bacterial production of metabolites, such as antibiotics and hydrogen cyanide, which directly inhibit the pathogen, (Kloepper et al 1999).…”

“…Disease suppressing effects may spread onto neighbouring plants if roots intermingle freely, although this has not been verified. It has been shown that species-rich grasslands and pastures harbour higher levels of PGPR than homogenous grasslands (Eisenhauer 2012). Some cropassociated PGPR and AMF can activate a host plants chemical and/or physical defence mechanisms (Kloepper et al 1999;Eisenhauer 2012;Monteiro et al 2012).…”

“…These include: (i) more efficient and complementary use of available resources and niches (Malézieux et al 2009;Tosti and Guiducci 2010); (ii) facilitation via the roots (Vandermeer 1989;Hauggaard-Nielsen and Jensen 2005); (iii) enhanced soil fertility by intercropping nitrogen-fixers (HauggaardNielsen and Jensen 2005); (iv) increased resilience against pests and diseases (Trenbath 1993); (v) increased abiotic stress resistance due to higher levels of functional diversity within the system and resultant complex interactions between associated ecological and biochemical processes (Eisenhauer 2012;George et al 2012).…”