State-of-the-art and objectives

Main Objectives and Overarching Hypothesis

The functioning and service supply of ecosystems in the face of anthropogenic environmental and biodiversity change represents a cornerstone of ecological research and a pressing societal issue. Despite broad consensus about a positive BEF relationship, the underlying ecological mechanisms and their context-dependencies are not well understood. This proposal aims at filling this knowledge gap by providing a novel conceptual framework for integrating biotic interactions across guilds of organisms, more specifically between plants and mycorrhizal types, to explain resource-use complementarity in plants and its consequences for plant performance and community multifunctionality. Using a combination of field and mesocosm experiments, as well as meta-level analyses (Fig. 1a), the proposed work will test the overarching hypothesis that ecosystem functioning increases when more tree species associate with functionally dissimilar mycorrhizal fungi. This is because – in addition to other trait differences between tree species – different mycorrhizal types will increase coverage of biotope space for and reduce competition amongst plants, subsequently increasing resource-use complementarity. Taking a whole-ecosystem perspective (Fig. 1b), we propose to explore the role of interactions between trees and mycorrhizal fungi in driving biodiversity effects on ecosystem functioning (I) and how these interactions influence as well as depend on nutrient dynamics and ecosystem stoichiometry (II). Given the increasing environmental pressures that forests face, the need for land managers to adapt to climate change and the significant role that mycorrhizal fungi play in soil nutrient and water uptake, tree diversity–ecosystem function relationships will be investigated under ambient climatic and drought conditions (III). Resulting ecosystem consequences will be explored by studying main energy channels and ecosystem multifunctionality using food web energy fluxes (IV) and by assessing soil carbon storage (V). Finally, integration of such knowledge on the drivers of mycorrhiza-mediated BEF mechanisms will allow us to understand context-dependent BEF relationships (VI). This interdisciplinary and integrative project spans the whole gradient from local-scale process assessments to global ecological relationships by building on unique experimental infrastructures like the MyDiv Experiment and the iDiv Ecotron and the global tree diversity experimental network TreeDivNet, to link the main ecological mechanisms to reforestation initiatives in order to provide management recommendations (Fig. 1a). The proposed work thus represents a novel combination of multiple experimental platforms to advance BEF research and to provide a predictive framework for context-dependent BEF relationships. This innovative combination of basic research with real-world applications links trait-based community ecology, global change research and ecosystem ecology, pioneering a new generation of BEF research and represents a significant step towards implementing multitrophic BEF theory for human needs.

a

b

Figure 1.

Structure, research platforms and work packages (WPs) of the proposed project. (A) WPs will work and collaborate in four main research platforms. Hypothesised mechanisms between biodiversity and ecosystem function (BEF) will be studied in the MyDiv Experiment and the iDiv Ecotron. While the MyDiv Experiment allows exploring BEF relationships under natural environmental conditions, the iDiv Ecotron enables studies under more controlled conditions and the test of additional drivers (e.g. nutrients, drought). The global experimental network TreeDivNet will allow us to generalise our findings and/or to study context-dependent BEF relationships. The local reforestation site Neue Harth will allow us to directly test the real-world, management-relevant implications of BEF relationships. Platforms are represented with different icons that are used in (B) to indicate which WP builds on these platforms. The six different WPs take complementary approaches to study important ecosystem components and facilitate synthesis.

Methodology

From Experiments to Real World: the Platforms Used across the Proposal

The MyDiv Experiment – a Field Experiment on the Role of Mycorrhizae in BEF

In 2015, the MyDiv Experiment (Fig. 2a; https://www.idiv.de/en/mydiv) was set up to address critical knowledge gaps related to biotic interactions as underlying mechanisms of BEF relationships and the role of mycorrhizal types in resource-use complementarity in plant communities in particular (Ferlian et al. 2018a, Ferlian et al. 2018b). The experiment was established to test the main hypothesis that tree communities with diverse mycorrhizal types will show increased soil resource-use complementarity compared to tree communities with a single mycorrhizal type. Therefore, treatments combining high tree species richness with the presence of both mycorrhizal types are expected to increase resource uptake and, consequently, resource-use complementarity – in addition to other complementarities, for example, crown heights and shapes – resulting in the highest levels of ecosystem functioning (Fig. 2b). The MyDiv Experiment manipulates the two main mycorrhizal types (via tree species selection) along a deciduous tree species richness gradient comprising monocultures, two-species and four-species mixtures. The mycorrhizal treatment is comprised of tree communities that, according to literature, predominantly associate with AMF (five tree species; Acer pseudoplatanus, Aesculus hippocastanum, Fraxinus excelsior, Prunus avium and Sorbus aucuparia), EMF (five tree species; Betula pendula, Carpinus betulus, Fagus sylvatica, Quercus petraea and Tilia platyphyllos) or mixtures of these ten tree species. The site, design, basal measurements and evidence for the successful establishment of the MyDiv Experiment are provided in Ferlian et al. (2018b). In preparation of this proposal, we analysed the roots of all tree species in all plots in autumn 2019 to verify the successful establishment of the experimental treatments. Next-generation sequencing (NGS) and traditional staining of root material confirmed that AMF trees are primarily colonised by AMF and EMF trees are primarily colonised by EMF (analysed in 2017; [Heklau et al. 2021]). The MyDiv Experiment includes specimens of an oak clone phytometer (PhytOakMeter; Herrmann et al. 2016) and is part of the global network of tree diversity experiments ‘TreeDivNet’ (Paquette et al. 2018). Phytometers enable highly standardised physiological process measurements in response to the abiotic and biotic environment (Eisenhauer et al. 2018a).

a

b

Figure 2.

(A) Location of the MyDiv Experiment, experimental design with colour coding and within-plot experimental design with the core area (light grey) and planting pattern (Ferlian et al. 2018b). (B) Conceptual figure illustrating the main hypothesis (BEF plot) and the underlying resource-use scenarios in tree species that co-exist in a community and are limited by a set of resources (biotope-space quadrats; n = 10 for treatment/coloured quadrat). AMF: arbuscular mycorrhizal fungi, EMF: ectomycorrhizal fungi, Both: both mycorrhizal types. The positive relationship between tree species richness (1, 2 and 4 species) and ecosystem functioning is expected to differ amongst tree communities. Communities of only AMF tree species will have higher ecosystem functioning and show stronger tree diversity effects compared with only EMF tree species, as indicated by different intercepts and slopes of the relationships, respectively. The soil at the experimental site is N-rich and presumably P-limited, favouring AMF-tree species performance. Accordingly, the biotope space occupied by the tree species (represented by circles with different line types; black circles: EMF species, white circles: AMF species) in each community differs as indicated by different positions of the circles within the boxes. We expect that ecosystem functioning will be highest at the highest tree diversity level in tree communities associated with both mycorrhizal types. Here, soil resource-use complementarity should be maximised as indicated by the lowest level of overlap amongst circles and the highest exploitation of the available biotope space. Figures were modified after Ferlian et al. (2018b).

Notably, given the significant establishment effects of ecological experiments, including disturbances (Eisenhauer et al. 2012b), the proposed research is the first focusing on the MyDiv Experiment. This means that the proposed research is not the continuation of any funded project, but a novel, concerted programme to advance ecosystem research. This research programme is well prepared. From the start of the experiment, we established a series of continuous measurements that will serve as important baseline information for all work packages (WPs). The respective data are stored in a standardised way in the iDiv database. In yearly tree inventories, we have been measuring tree height, diameter at breast and at 5 cm height, vitality and damage in all trees forming the core area of each plot (n = 64 trees; Fig. 2a). Moreover, we are performing yearly measurements of wood decomposition rates, soil microbial biomass and respiration, while microbial community structure via NGS and PLFAs/NLFAs (see below) is assessed every second year. Key chemical and physical soil variables (soil pH and C, N and P) are also measured every second year. Soil texture was assessed in 2015. Additionally, a soil core of 1 m depth was taken from each plot in 2015 and 2020, subdivided into eight layers (0-5, 5-10, 10-20, 20-30, 30-40, 40-50, 50-60 and 60-100 cm depth) and archived. This sampling will be repeated every 5 years to study soil C sequestration (Lange et al. 2015).

The iDiv Ecotron – an Experimental Facility to Study Multitrophic BEF

Recently, the iDiv Ecotron was set up to address the perpetual claim that BEF research in terrestrial ecosystems needs to move beyond the manipulation of diversity at single trophic levels to embrace the multitrophic complexity of ecological communities (Naeem et al. 1994, Eisenhauer and Türke 2018, Eisenhauer et al. 2019b, Schmidt et al. 2021). This facility symbolises a paradigm shift in biodiversity research: while multitrophic biodiversity has long been studied as one important response variable in changing ecosystems, for example, by the use of climate chambers, these novel ‘biodiversity chambers’ now allow international and interdisciplinary teams of researchers to explore the consequences of different scenarios of multitrophic biodiversity change and alterations of biotic interactions for multiple ecosystem functions (Soliveres et al. 2016) in above- and belowground networks (Wardle et al. 2004, Schmidt et al. 2021). The iDiv Ecotron is composed of 24 highly flexible EcoUnits (Fig. 3a, b). The size of the EcoUnits enables the maintenance and study of complex food webs of specialist and generalist invertebrates across several months, as well as interactions amongst tree saplings of different species (Fig. 3c). Moreover, the lysimeter configuration allows us to incubate intact soil monoliths (diameter: 0.5 m; depth: 0.8 m; Fig. 3b) with the complex soil communities therein. The possible compartmentalisation of each EcoUnit into four independent subunits (i.e. 96 subunits in total) enables experiments with high replication. Moreover, all EcoUnits are equipped with a video-camera system, freely-programmable multi-colour (wavelength) LED lamps, irrigation system and temperature gradient along the soil profile to enable the spatial and temporal control of environmental factors, as well as the simulation and study of environmental gradients within and across EcoUnits.

a

b

c

Figure 3.

The iDiv Ecotron. (A) Photo showing the iDiv Ecotron facility with EcoUnits. (B) Technical drawing of an EcoUnit illustrating the lysimeter function with soil sensors and root scanners. (C) Photo of a preliminary experiment in preparation of this proposal with beech saplings. In the proposed experiments, we will use the same lysimeter set-up to be able to incubate up to 96 independent mesocosms. Figures were modified after Schmidt et al. (2021).

TreeDivNet – a Global Network of Tree Diversity Experiments

The global nature of environmental problems, such as climate change, desertification and biodiversity loss, requires the establishment of research approaches that, in most cases, exceed the capacity of single countries or research groups (Eisenhauer et al. 2019b) and that cover a wide range of environmental and geographical conditions (Maestre and Eisenhauer 2019). As a consequence, interdisciplinary and international collaboration in ecology (and beyond) has expanded significantly in the last decade (Craven et al. 2019) and there is growing interest in developing global networks of ecological experiments and surveys (Maestre and Eisenhauer 2019). Collaborative research networks, such as the Nutrient Network (Borer et al. 2014) and TreeDivNet (Verheyen et al. 2016; https://treedivnet.ugent.be), have provided key scientific insights into how natural and semi-natural ecosystems function and respond to multiple global environmental change drivers (Maestre and Eisenhauer 2019). Here, we propose to work in the global network of tree diversity experiments TreeDivNet that encompasses > 1.1 million trees in 28 experiments (Fig. 4; Paquette et al. 2018) to study context-dependent biotic interactions and BEF relationships. First syntheses across participating experiments exemplify the collaborative nature and scientific power of this network (e.g. Grossman et al. 2018, Cesarz et al. 2022We have been involved in TreeDivNet since 2015 through our own add-on studies (Cesarz et al. 2022) and the participation of the MyDiv Experiment (Ferlian et al. 2018b). Preliminary analyses in preparation of this proposal indicate that mycorrhizal type can be used as a tree trait in syntheses given the representation of AMF and EMF species across experiments (Fig. 4). Using data from the experiments and the TRY database (Kattge et al. 2011), we compiled a novel database of mycorrhizal association types for 454 unique tree species-experiment combinations. This information will be verified using NGS in selected experiments and used as an explanatory variable in meta-level analyses. In 2013, we led a study on soil microbial biomass and activity in eleven TreeDivNet experiments (Cesarz et al. 2022), setting an important baseline regarding: (1) experience leading projects within this network, (2) establishing collaborations with many TreeDivNet members and (3) starting a database on soil abiotic and biotic properties.

Figure 4.  

The global network of tree diversity experiments “TreeDivNet”. Each experimental site is represented by one pie chart (some experiments have multiple sites). The sizes of the pie charts correspond to the respective tree species pool of the experiment. Based on information from TRY (retrieved in December 2019; Kattge et al. 2011), the representation of different mycorrhizal types in tree species is indicated by different colours. This dataset will be made available to all TreeDivNet members.

Neue Harth – a Reforestation Initiative after Open Coal Mining

There are many human activities that threaten the biodiversity and functioning of ecosystems, but habitat destruction is one of the most pervasive ones (Díaz et al. 2019). Many natural ecosystems have been destroyed in the course of land-use change. One of the most devastating examples is open-coal mining, which basically results in purely mineral soils, often with low water-holding capacity, being brought to the surface and then requiring restoration. In Germany, coal production mainly serves the purpose of electrical power generation. According to the occurrence of brown coal, major formerly-forested areas have been destroyed in Central Germany (“Mitteldeutsches Braunkohlerevier”; Fig. 5a). After coal production, ecosystems are restored and are supposed to serve multiple purposes, such as recreation, biodiversity maintenance and agricultural production. Land managers also aim at restoring multifunctional forests, such as the case in the area of the “Neue Harth” in the south of Leipzig, Germany (Fig. 5b).

a

b

Figure 5.

Reforestation of destroyed ecosystems. (A) Consequences of open coal mining in the south of Leipzig, Germany (2009; photo: Ronny Schmidt, GeoWerkstatt Leipzig e.V.). Roughly 800 ha of mixed forest were destroyed between 1921 and 1999. (B) Reforested area close to Leipzig, Germany (2015; photo: N. Eisenhauer). Forest patches were planted as monocultures and mixed forests of different diversity levels and now allow the study of the ecosystem consequences of different management decisions.

We have been in contact with the forest managers of the Neue Harth, who strongly support scientific work in these reforested areas. Together, we were able to assess the extent, tree species identity and diversity of restored forest patches. In this area, we defined 18 independent ~ 20-year old forest stands (> 2 ha each), containing 10 different tree species associating with different mycorrhizal types (Acer campestre [AMF], Acer platanoides [AMF], Betula pendula [EMF], Fagus sylvatica [EMF], Robinia pseudoacacia [AMF; association with N-fixing rhizobacteria], Tilia cordata [EMF], Pinus sylvestris [EMF], Populus balsamifera [EMF], Quercus rubra [EMF] and Quercus robur [EMF]), ranging from monocultures to 6-species mixtures. This setting represents a real-world reforestation scenario with tree species of high local relevance. The two oak species (with Q. robur being the phytometer species in the MyDiv Experiment) occur in replicated monocultures (n = 2 for both species), 2-species mixtures (n = 3) and 5-species mixtures (n = 3), enabling studies on the ecosystem consequences of diversifying oak plantations both in terms of tree species richness and mycorrhizal type. Further, recently developed analytical methods will allow us to explore complementarity and selection effects with these data (Clark et al. 2019). Similar starting conditions (e.g. disturbed soil) and planting procedures (e.g. tree species, planting density) facilitate direct comparison between reforestation sites and tree diversity experiments, which is often challenging in other systems/set-ups (Eisenhauer et al. 2016).

Work Packages

The proposed work is divided into six highly complementary work packages (WPs; addressing the six main objectives outlined above) that are further subdivided into 18 tasks (TAs) in total. Four WPs will be carried out by more experienced scientists (Prof. Dr. Nico Eisenhauer and three postdocs) and the other two WPs will be conducted by PhD students. Each scientific TA is supposed to deliver at least one publication in an international, peer-reviewed journal. Team members will have complementary expertise and work together in joint experiments, sampling campaigns and synthesis projects. WPs I and VI will provide the conceptual backbone of the project, integrate the information from all other WPs and facilitate collaboration through multiple workshops. This interdisciplinary and integrative project ranges from local-scale process studies to global syntheses, to link the main ecological mechanisms to reforestation initiatives. The interdisciplinary nature of the project will build bridges between microbial, plant and ecosystem ecology and between basic research and applied aspects related to the restoration of multifunctional forests.

WP I: Biodiversity effects

This WP will focus on the strength of BEF relationships and how net biodiversity effects (NBEs), complementarity effects (CEs) and selection effects (SEs) (based on the additive partitioning method; Loreau and Hector 2001) are modulated by mycorrhizal fungi. The overarching hypotheses are that NBEs and CEs will be strongest when high-diversity tree communities associate with a high diversity of functionally dissimilar mycorrhizal types (H-I-1; Eisenhauer 2012); and that biodiversity effects change over time, with a dominance of SEs in young experiments/early years and increasing NBEs and CEs over time (H-I-2; Eisenhauer et al. 2012b, Reich et al. 2012, Huang et al. 2018).

This WP will support all other WPs by coordinating the planned work, providing baseline data for internal and external collaborators, as well as supervising and mentoring postdocs and PhD students (TA-1-1). To provide baseline data on root mycorrhization for all other WPs, we will analyse the diversity and colonisation rate of AMF and EMF in roots using microscopy and NGS (amplicon and shotgun sequencing) in collaboration with iDiv’s Metagenomics Support Unit (Prof. Dr. Francois Buscot and Dr. Anna Heintz-Buschart). We will analyse the mycorrhiza diversity in tree roots in the MyDiv Experiment and in four selected experiments in TreeDivNet. These additional experiments (IDENT-Montreal, IDENT-FAB, IDENT-Macomer, BEF China) were chosen based on the criteria that they: (i) have at least three AMF and three EMF tree species in their species pool, (ii) were set up > 5 years ago and (iii) have the same diversity levels as the MyDiv Experiment (1, 2 and 4 species).

Similar to what was done in 2017 (Heklau et al. 2021) and 2019 in the MyDiv Experiment, we will sample roots of three AMF and EMF tree species, respectively, with five replicates per diversity level (4 experiments x 6 tree species x 3 diversity levels x 5 replicates = 360 samples in total). In the MyDiv Experiment, we will analyse roots of all tree species for all plots (200 samples). The collected root material will be split into two subsamples. One will be immediately frozen and stored for DNA extraction and NGS (mycorrhiza diversity); the second subsample will be fixed in formaldehyde-acetic acid (AMF; Eisenhauer et al. 2009) and 10% glycerine solution (-20°C; EMF), respectively, to determine root colonisation rates by mycorrhizal fungi. While analysing data from all five experiments will allow us to study general patterns of mycorrhiza diversity across tree diversity gradients, the repeated sampling in the MyDiv Experiment will allow us to explore potential changes over time. In this WP, we will focus on tree growth as a key measure of ecosystem functioning related to biomass production and C sequestration. In TA-I-2, we will analyse NBEs, CE and SEs (Reich et al. 2012) as affected by tree diversity, mycorrhizal type and experiment year (2015-2022) in the MyDiv Experiment, based on yearly forest inventory data on all tree individuals in the core area. In TA-I-3, we will perform a meta-level analysis of tree diversity effects (NBEs, CE and SEs) on tree biomass production as affected by mycorrhizal fungi (Fig. 4) across TreeDivNet experiments (extending the dataset and analyses of Guerrero-Ramírez et al. 2017). This WP will be led by Prof. Dr. Nico Eisenhauer. In WP I, we will collaborate with all members of the Scientific Advisory Board (SAB; see below) and organise the kick-off workshop (Fig. 6).

Figure 6.  

Timetable of the proposed project. Given are the main research platforms and the duration of each task (TA) within work packages (WPs). Pin icon: workshops; sheet icon: regular ERC reporting; K: Kick-off workshop, H: Hands-on workshop; W: Wrap-up workshop; hand icon: requested personnel. Icons on TAs indicate the research platform where the research will be conducted to illustrate the potential for collaboration.

Work package II: Nutrient dynamics

This WP will investigate the potential nutrient-related mechanisms underlying mycorrhiza-mediated tree diversity effects. Taxonomically and functionally diverse mycorrhizal communities may increase ecosystem functioning by enhancing the access and use of the available resource pool to plants resulting in relaxed plant-plant competition for soil resources (van der Heijden et al. 1998, Klironomos et al. 2000). Thus, we expect that the presence of two distinct mycorrhizal types with different lifestyles and foraging strategies (AMF and EMF) may have important implications for resource partitioning amongst their associated plant hosts and for plant and soil stoichiometry (H-II-1; Ferlian et al. 2018b). Moreover, more fertile soils and/or the addition of limiting N and P as mineral fertilisers should reduce the beneficial mycorrhiza effect on tree communities (H-II-2; Suz et al. 2014).

In this WP, we will focus on soil nutrient dynamics as well as plant and soil stoichiometry as affected by tree diversity and mycorrhizal types. In TA-II-1, we will study C, N and P concentrations of leaves, soil and soil microbial biomass in the MyDiv Experiment. Briefly, as done in Ferlian et al. (2017), 10 vital, intact and mature sun leaves will be collected from different branches of five tree individuals per species and plot. In addition, ~ 200 g of soil will be taken from the root zone of each tree at a depth of 0–10 cm for soil and soil microbial analyses. Part of the collected leaf and soil material will be dried, ground and transferred into tin capsules for C and N analyses using an elemental analyser (Vario EL II, Elementar Analysensysteme GmbH, Hanau, Germany). Plant and soil P concentrations will be determined by measuring digested material via inductively coupled plasma optical emission spectroscopy as done in Guiz et al. (2018). Microbial biomass C and N will be determined by a chloroform fumigation-extraction method (Brookes et al. 1985). Similarly, microbial biomass P will be measured using a combination of methods proposed by McLaughlin et al. (1986) and Kouno et al. (1995) that is also based on comparisons between fumigated and non-fumigated soils. In TA-II-2, we will analyse leaves and soil from 10 selected long-term TreeDivNet sites that differ in soil fertility and water availability (Cesarz et al. 2022), but have approx. equal representation of AMF and EMF tree species (Fig. 4). Following the same methods as in TA-II-1, we will determine leaf and soil CNP. In TA-II-3, we will perform a mesocosm experiment in the iDiv Ecotron (Schmidt et al. 2021). We will use the lysimeter set up of the iDiv Ecotron to establish 22 different tree communities. We will set up monocultures of all ten tree species of the MyDiv Experiment species pool (n = 10), as well as twelve different four-species mixtures: four containing only AMF tree species, four containing only EMF species and four containing both AMF and EMF species (two species per mycorrhizal type). These 22 communities will be incubated under four different nutrient treatments: ambient nutrient conditions, addition of N, addition of P and addition of both N and P (n = 88 in total). Mineral fertiliser amounts will be added according to the protocol of the IDENT site in Freiburg. We will plant four tree saplings per lysimeter. The soil will be steam-sterilised prior to filling the lysimeters, thoroughly washed and re-inoculated with 2 kg of fresh soil from the respective plot of the MyDiv Experiment (taken outside of the core area). The experiment will run for 8 months. As described in TA-II-1, we will analyse CNP concentrations of leaves, soil and soil microbial biomass to explore potential shifts in ecosystem stoichiometry in response to the nutrient addition, tree diversity and mycorrhiza treatments. For TA-II-4, we will use the Ecotron experiment of TA-II-3 to perform a tracer study to explore tree nutrient uptake as affected by the tree and mycorrhiza treatments. To this end, we will use ¹⁵N-labelled tree litter material (Eisenhauer et al. 2012a), as well as rare elements (Li⁺, Rb⁺, Sr²⁺) applied to the soil (Gockele et al. 2014) and nutrient tracer concentrations will be measured according to Gockele et al. (2014). This work will be supported by Dr. Annette Jesch (nee Gockele), who is the lead author of the cited tracer study and in my lab for the next three years. A postdoc with experience in plant and soil ecology, experimental ecology and meta-analysis will lead this WP and collaborate with Prof. Kris Verheyen (SAB, forest BEF) and Prof. Matthias Rillig (SAB; mycorrhizal ecology).

Work package III: Drought resistance

This WP will investigate if mycorrhizal fungi can mitigate drought effects on trees. The increasing frequency and intensity of droughts is threatening the biodiversity and functioning of forest ecosystems (Anderegg et al. 2013). Management strategies aimed at buffering climate change effects include planting tree mixtures rather than tree monocultures, as the latter might have a higher susceptibility to detrimental drought effects (Hutchison et al. 2018). Mycorrhizal fungi do not only play a major role in soil N and P uptake, but the extensive hyphal network is also involved in water uptake and may mitigate detrimental drought effects on plants (Augé 2001). The overarching hypotheses are that tree stands with a higher tree diversity and mycorrhiza diversity will be more resistant to drought stress (H-III-1; Isbell et al. 2015, Craven et al. 2018, Eisenhauer 2018a); and that tree individuals in stands with low intraspecific competition and neighbours with dissimilar mycorrhizal types will experience less drought stress across environmental fluctuations (H-III-2; Salmon et al. 2018).

In this WP, we will focus on tree growth, survival and physiology as important indicators of tree performance under drought conditions. In TA-III-1, we will analyse detailed tree inventory data from the MyDiv Experiment including the exceptionally dry summers in 2018 and 2019. We will analyse tree growth and mortality as well as δ¹³C in leaves as a proxy of stomatal conductance (as done in Eisenhauer and Scheu 2008; leaf material was collected in 2018 and 2019 and will be compared with leaf δ¹³C during normal years). Moreover, we will perform drought-event-based drone flights (~ 2 per year; one during the drought and during a normal reference period), equipped with a hyperspectral and thermal camera for leaf water content (Fang et al. 2017) and stomatal conductance proxies (Sagan et al. 2019), respectively. For calibration, leaf water content and stomatal measurements will be conducted in parallel at the species level. Together, these measurements allow us explore tree physiology as affected by tree diversity and mycorrhiza type and current environmental conditions and natural fluctuations. In TA-III-2, we will perform a meta-level analysis of tree diversity effects on the detrended temporal stability (Isbell et al. 2015) of tree biomass production (annual increment) as affected by mycorrhizal fungi across experiments of TreeDivNet (Guerrero-Ramírez et al. 2017). In TA-III-3, we will perform a mesocosm experiment in the iDiv Ecotron (Schmidt et al. 2021) to study the effects of tree diversity, mycorrhizal type and drought under standardised conditions that will allow us to investigate tree-mycorrhiza interactions, as well as tree physiological responses (leaf thickness, N content, specific leaf area, leaf conductance) in more detail (Sendek et al. 2019). In short, using the lysimeter function of the iDiv Ecotron, we will set up replicated monocultures of all 10 tree species of the MyDiv Experiment species pool (n = 20; Ferlian et al. 2018b) and 20 different four-species mixtures: all five possible combinations of only AMF tree species, all five possible combinations of only EMF species and 10 selected combinations of AMF and EMF species (representing all replicates of the monocultures and four-species mixtures of the MyDiv Experiment). These 40 communities will be incubated under ambient rainfall (precipitation events every other day) and under reduced rainfall (-50%, every fourth day; Sendek et al. 2019; n = 80 in total). We will plant four tree saplings per lysimeter. The soil will be steam-sterilised prior to filling the lysimeters, thoroughly washed and re-inoculated with 2 kg of fresh soil from the respective plot of the MyDiv Experiment (taken outside of the core area). The experiment will run for 8 months. We will perform repeated assessments of tree growth and physiology (see above), for example, related to water stress (δ¹³C), as well as soil biological activity using soil microbial respiration and detritivore feeding activity (Eisenhauer et al. 2018a, Thakur et al. 2018). This WP will be led by a postdoc with experience in plant physiology, experimental ecology and meta-level analysis. In WP-III, we will collaborate with Prof. Kris Verheyen (SAB; forest BEF), Prof. Dr. Bernhard Schmid (SAB; BEF theory) and Prof. Dr. Christian Wirth (plant ecology & physiology, proximal and remote sensing).

Work package IV: Energy flux

This WP will investigate tree diversity and mycorrhiza effects on energy flux and ecosystem multifunctionality. Biodiversity is known to determine multitrophic energy use efficiency, flow and storage in grasslands (Buzhdygan et al. 2020). In high-diversity plant communities, a higher quantity and diversity of plant inputs was shown to favour a more fungi-dominated soil microbial community (Eisenhauer et al. 2017) that may play a critical role in soil carbon storage (Lange et al. 2015). Thus, the ratio between bacterial and fungal biomass may provide important insights into soil microbial functioning and efficiency (Eisenhauer et al. 2010). Such shifts in microbial community composition are likely to have cascading effects on higher trophic levels (Scherber et al. 2010, Eisenhauer et al. 2013) and thereby influence ecosystem multifunctionality (Eisenhauer et al. 2018b, Meyer et al. 2018). Multitrophic ecosystem multifunctionality can be inferred from the energy flux through soil food webs (Schwarz et al. 2017, Barnes et al. 2018, Barnes et al. 2020). The overarching hypotheses of this WP are that tree diversity increases the relative importance of the fungal energy channel in the soil, particularly so in the presence of functionally dissimilar mycorrhizal fungi (H-V-1; Eisenhauer et al. 2017), ultimately increasing soil energy flux and multitrophic ecosystem multifunctionality (H-V-2; Barnes et al. 2018).

In this WP, we will explore the structure and functioning of soil food webs. In TA-IV-1, we will collect soil from 12 selected long-term tree diversity experiments in TreeDivNet (Fig. 4; including the MyDiv Experiment; as done before, but increasing the number of experiments in comparison to Cesarz et al. 2022) and analyse the biomass of major soil microbial groups using phospholipid and neutral fatty acid analysis (PLFAs and NLFAs; Wagner et al. 2015). In TA-IV-2, we will establish two subplots of 4 x 4 m in the MyDiv Experiment to manipulate tree resource inputs into the soil. Both subplots will receive a water-permeable weed tarp that will allow us to manipulate aboveground litter input. On one subplot per plot, we will remove the collected leaf material (belowground plant inputs only), while we will put collected leaf litter under the tarp of the other subplot (aboveground and belowground plant inputs). We will analyse the soil food web structure by studying soil microbial communities (P/NLFAs), nematodes and soil meso- and macrofauna to determine the main energy channels (Eisenhauer et al. 2013, Eisenhauer et al. 2017). We expect to see stronger EMF effects in the treatment with aboveground plant inputs due to their role as saprotrophs (van der Heijden et al. 2015), providing an experimental test for the hypothesis that the different mycorrhiza types provide nutrients from complementary sources (Ferlian et al. 2018b). In TA-IV-3, we will explore multitrophic ecosystem multifunctionality by modelling energy fluxes in soil food webs in the MyDiv Experiment. The calculations of energy flux will be based on a well-established quantitative food-web method (Barnes et al. 2018, Gauzens et al. 2019). Using data of TA-IV-2, the topology of the network, group metabolic demand, energy loss to predation, assimilation efficiencies and feeding preferences, we will calculate energy fluxes through each of these communities using the ‘fluxweb’ package in R (Gauzens et al. 2019). This approach has been used successfully to determine belowground herbivory, detritivory and predation (Schwarz et al. 2017, Barnes et al. 2020), as well as ecosystem multifunctionality (Barnes et al. 2018). This WP will be led by a PhD student with a strong background in soil animal ecology and statistical modelling. We will collaborate with Prof. Dr. Ulrich Brose (food web modelling); the student will be co-supervised by Dr. Olga Ferlian (soil energy channels).

Work package V: Carbon sequestration

This WP will investigate tree diversity and mycorrhiza effects on soil C storage. Plant diversity has been shown to increase grassland soil C storage (Fornara and Tilman 2008, Lange et al. 2015) by favouring a more fungi-dominated soil microbial community (Lange et al. 2015, Liu et al. 2018). Although mycorrhiza are known to play a critical role in soil C storage (Averill et al. 2014), interaction effects of AMF and EMF have not been studied so far in a tree diversity context. Our main hypotheses are that high-diversity forests with functionally dissimilar mycorrhizal types have higher soil C storage than low-diversity forests (H-V-1; Ferlian et al. 2018b); and that this effect is mediated by a more active soil microbial community (H-V-II; Lange et al. 2015).

In this WP, we will investigate the drivers of soil C storage. In TA-V-1, we will collect soil from all 28 tree diversity experiments in TreeDivNet (Fig. 4; as done before, Cesarz et al. 2022) and analyse total soil organic C concentration (Lange et al. 2015) and active soil microbial biomass (Eisenhauer et al. 2010). In 2021, a total of ten soil subsamples (soil depths 0-10 cm and 10-50 cm) will be taken per plot to create a bulk sample. Part of this sample will be used for soil C analysis (a, dry), while another part will be used for microbial analyses (b, fresh): (a) The soil will be sieved (2 mm mesh), dried and milled. Total C of ground samples will be determined by an elemental analyser after combustion at 1,150°C (Elementaranalysator vario Max CN, Elementar Analysensysteme GmbH, Hanau, Germany). Inorganic C concentration will be measured by elemental analysis after removing organic C for 16 h at 450°C in a muffle furnace by oxidation. Organic C concentration will be calculated from the difference between total and inorganic C concentrations (Lange et al. 2015). C stocks will be calculated as the product of bulk soil density and its concentration of C (Schrumpf et al. 2011); (b) The fresh soil will be sieved at 2 mm and active soil microbial biomass will be determined via substrate-induced respiration using an O₂-microcompensation apparatus (Eisenhauer et al. 2018b). Data on soil P/NLFAs from TA-IV-1 from a subset of the TreeDivNet experiments will allow more detailed analyses of relationships amongst microbial community structure, activity and soil C storage. Moreover, in TA-V-2, we can build on the database of a previous project in TreeDivNet (Cesarz et al. 2022) that can be used to explore the change of tree diversity effects on soil microbial properties over time (Thakur et al. 2015) and how this is affected by mycorrhizal type. In TA-V-3, we will test the real-world implications of the findings from BEF experiments by assessing soil C storage in the reforestation plantations of the Neue Harth (Fig. 5b). As done in TA-V-1, we will determine soil organic C concentrations, soil microbial community structure (P/NLFAs) and soil microbial activity to test if diversifying oak plantations has any beneficial effects on soil microbial functions and C storage. This WP will be led by a PhD student with a strong background in soil ecology, who will be co-supervised by Dr. Simone Cesarz (soil microbial communities and functions) and supported by Prof. Dr. Kris Verheyen (SAB, forest BEF), Prof. Dr. Bernhard Schmid (SAB, forest BEF) and Prof. Dr. Christian Wirth (forest carbon dynamics).

Work package VI: Context dependency

This WP will investigate the context dependency of BEF relationships (Eisenhauer et al. 2019b) and the underlying role of tree-mycorrhiza interactions in different environmental conditions (Hoeksema et al. 2010). Empirical evidence is mounting that the consequences of biodiversity change may not be predictable from a single, universal BEF relationship (Baert et al. 2018). Although, the different shapes of BEF relationships have been synthesised before (Eisenhauer et al. 2019b), a mechanistic understanding of such variable biodiversity effects is elusive. Considering the changes in key biotic interactions is highly promising not only to better understand and predict BEF relationships, but also to develop sustainable management strategies under different environmental conditions. Our main hypotheses are that changes in tree-mycorrhiza interactions across environmental contexts are a powerful predictor of tree diversity-ecosystem functioning relationships (H-VI-1); and that tree diversity effects on ecosystem functioning will increase: (a) under nutrient- and water-limited conditions and (b) with an increasing number of environmental contexts and ecosystem functions (H-VI-II; Isbell et al. 2011).

In this WP, we will integrate work across all other WPs by investigating the context dependency of BEF relationships and the role of tree-mycorrhiza interactions explaining these differences. In TA-VI-1, we will build on an extensive literature review of empirical and theoretical work on this topic, as well as discussions in workshops (Fig. 6) to produce a review paper outlining how different environmental conditions should influence plant-mycorrhiza interactions and how these altered biotic interactions may shape BEF relationships. In TA-VI-2, we will perform a meta-analysis of published data and data produced in WPs I – V on the role of mycorrhizal fungi in tree diversity effects on ecosystem functioning as affected by different environmental conditions (e.g. soil fertility and water availability; Baert et al. 2018), the number and identity of ecosystem functions (Isbell et al. 2011, Meyer et al. 2018), different ecosystem compartments and soil layers (Xu et al. 2020, Xu et al. 2021) and different temporal and spatial scales (Eisenhauer et al. 2012b, Eisenhauer et al. 2019b). This WP will be led by a postdoc with a strong background in ecological theory, synthesis and meta-level analyses. In WP VI, we will collaborate with all members of the Scientific Advisory Board (SAB; see below) and organise two workshops (“Hands-on” and “Wrap-up”; Fig. 6).

Acknowledgements

Proposal title

Acknowledgements

Funding program

Grant title

Hosting institution

Ethics and security

Author contributions

Conflicts of interest

References

Allen C, Macalady A, Chenchouni H, Bachelet D, McDowell N, Vennetier M, Kitzberger T, Rigling A, Breshears D, Hogg EH, Gonzalez P, Fensham R, Zhang Z, Castro J, Demidova N, Lim J, Allard G, Running S, Semerci A, Cobb N (2010)
A global overview of drought and heat-induced tree mortality reveals emerging climate change risks for forests
.
Forest Ecology and Management
259
(
4
):
660
‑
684
. https://doi.org/10.1016/j.foreco.2009.09.001
Anderegg WR, Kane JM, Anderegg LD (2013)
Consequences of widespread tree mortality triggered by drought and temperature stress
.
Nature Climate Change
3
(
1
):
30
‑
36
. https://doi.org/10.1038/nclimate1635
Argüello A, O'Brien MJ, van der Heijden MG, Wiemken A, Schmid B, Niklaus PA (2016)
Options of partners improve carbon for phosphorus trade in the arbuscular mycorrhizal mutualism
.
Ecology Letters
19
(
6
):
648
‑
656
. https://doi.org/10.1111/ele.12601
Augé RM (2001)
Water relations, drought and vesicular-arbuscular mycorrhizal symbiosis
.
Mycorrhiza
11
(
1
):
3
‑
42
. https://doi.org/10.1007/s005720100097
Averill C, Turner BL, Finzi AC (2014)
Mycorrhiza-mediated competition between plants and decomposers drives soil carbon storage
.
Nature
505
(
7484
):
543
‑
545
. https://doi.org/10.1038/nature12901
Averill C, Bhatnagar JM, Dietze MC, Pearse WD, Kivlin SN (2019)
Global imprint of mycorrhizal fungi on whole-plant nutrient economics
.
Proceedings of the National Academy of Sciences
116
(
46
):
23163
‑
23168
. https://doi.org/10.1073/pnas.1906655116
Baert JM, Eisenhauer N, Janssen CR, De Laender F (2018)
Biodiversity effects on ecosystem functioning respond unimodally to environmental stress
.
Ecology Letters
21
(
8
):
1191
‑
1199
. https://doi.org/10.1111/ele.13088
Barnes AD, Jochum M, Lefcheck JS, Eisenhauer N, Scherber C, O'Connor MI, Brose U (2018)
Energy flux: the link between multitrophic biodiversity and ecosystem functioning
.
Trends in Ecology & Evolution
33
(
3
):
186
‑
197
. https://doi.org/10.1016/j.tree.2017.12.007
Barnes AD, Scherber C, Brose U, Borer ET, Ebeling A, Gauzens B, Eisenhauer N (2020)
Biodiversity enhances the multitrophic control of arthropod herbivory
.
Science Advances
6
(
45
):
6603
. https://doi.org/10.1126/sciadv.abb6603
Barry K, Mommer L, van Ruijven J, Wirth C, Wright A, Bai Y, Connolly J, De Deyn G, de Kroon H, Isbell F, Milcu A, Roscher C, Scherer-Lorenzen M, Schmid B, Weigelt A (2019)
The Future of Complementarity: Disentangling Causes from Consequences
.
Trends in Ecology & Evolution
34
(
2
):
167
‑
180
. https://doi.org/10.1016/j.tree.2018.10.013
Barry KE, van Ruijven J, Mommer L, Bai Y, Beierkuhnlein C, Buchmann N, Hildebrandt A (2020)
Limited evidence for spatial resource partitioning across temperate grassland biodiversity experiments
.
Ecology
e02905
https://doi.org/10.1002/ecy.2905
Bertness MD, Callaway R (1994)
Positive interactions in communities
.
Trends in Ecology & Evolution
9
(
5
):
191
‑
193
. https://doi.org/10.1016/0169-5347(94)90088-4
Bever JD, Dickie IA, Facelli E, Facelli JM, Klironomos J, Moora M, Zobel M (2010)
Rooting theories of plant community ecology in microbial interactions
.
Trends in Ecology & Evolution
25
(
8
):
468
‑
478
. https://doi.org/10.1016/j.tree.2010.05.004
Bonfante P, Genre A (2010)
Mechanisms underlying beneficial plant-fungus interactions in mycorrhizal symbiosis
.
Nature Communications
1
(
1
):
1
‑
11
. https://doi.org/10.1038/ncomms1046
Borer ET, Harpole WS, Adler PB, Lind EM, Orrock JL, Seabloom EW, Smith MD (2014)
Finding generality in ecology: a model for globally distributed experiments
.
Methods in Ecology and Evolution
5
(
1
):
65
‑
73
. https://doi.org/10.1111/2041-210X.12125
Brookes PC, Landman A, Pruden G, Jenkinson DS (1985)
Chloroform fumigation and the release of soil nitrogen: a rapid direct extraction method to measure microbial biomass nitrogen in soil
.
Soil Biology and Biochemistry
17
(
6
):
837
‑
842
. https://doi.org/10.1016/0038-0717(85)90144-0
Brundrett MC (2009)
Mycorrhizal associations and other means of nutrition of vascular plants: understanding the global diversity of host plants by resolving conflicting information and developing reliable means of diagnosis
.
Plant and Soil
320
(
1-2
):
37
‑
77
. https://doi.org/10.1007/s11104-008-9877-9
Bruns TD, Shefferson RP (2004)
Evolutionary studies of ectomycorrhizal fungi: recent advances and future directions
.
Canadian Journal of Botany
82
(
8
):
1122
‑
1132
. https://doi.org/10.1139/b04-021
Brzostek ER, Dragoni D, Brown ZA, Phillips RP (2015)
Mycorrhizal type determines the magnitude and direction of root‐induced changes in decomposition in a temperate forest
.
New Phytologist
206
(
4
):
1274
‑
1282
. https://doi.org/10.1111/nph.13303
Buzhdygan OY, Meyer ST, Weisser WW, Eisenhauer N, Ebeling A, Borrett SR, Buchmann N, Cortois R, De Deyn GB, Kroon H, Gleixner G, Hertzog L, Hines J, Lange M, Mommer L, Ravenek J, Scherber C, Scherer-Lorenzen M, Scheu S, Schmid B, Steinauer K, Strecker T, Tietjen B, Vogel A, Wright A, Petermann JS (2020)
Biodiversity increases multitrophic energy use efficiency, flow, and storage in grasslands
.
Nature Ecology & Evolution
4
(
3
):
393
‑
405
. https://doi.org/10.1038/s41559-020-1123-8
Cardinale BJ, Matulich KL, Hooper DU, Byrnes JE, Duffy E, Gamfeldt L, Gonzalez A (2011)
The functional role of producer diversity in ecosystems
.
American Journal of Botany
98
(
3
):
572
‑
592
. https://doi.org/10.3732/ajb.1000364
Cardinale BJ, Duffy JE, Gonzalez A, Hooper DU, Perrings C, Venail P, Kinzig AP (2012)
Biodiversity loss and its impact on humanity
.
Nature
486
(
7401
):
59
‑
67
. https://doi.org/10.1038/nature11148
Cesarz S, Craven D, Auge H, Bruelheide H, Castagneyrol B, Gutknecht J, Eisenhauer N (2022)
Tree diversity effects on soil microbial biomass and respiration are context dependent across forest diversity experiments
.
Global Ecology and Biogeography
00
:
1
‑
14
. https://doi.org/10.1111/geb.13461
Cheeke TE, Phillips RP, Brzostek ER, Rosling A, Bever JD, Fransson P (2017)
Dominant mycorrhizal association of trees alters carbon and nutrient cycling by selecting for microbial groups with distinct enzyme function
.
New Phytologist
214
(
1
):
432
‑
442
. https://doi.org/10.1111/nph.14343
Chen L, Swenson NG, Ji N, Mi X, Ren H, Guo L, Ma K (2019)
Differential soil fungus accumulation and density dependence of trees in a subtropical forest
.
Science
366
(
6461
):
124
‑
128
. https://doi.org/10.1126/science.aau1361
Chen W, Koide RT, Adams TS, DeForest JL, Cheng L, Eissenstat DM (2016)
Root morphology and mycorrhizal symbioses together shape nutrient foraging strategies of temperate trees
.
Proceedings of the National Academy of Sciences
113
(
31
):
8741
‑
8746
. https://doi.org/10.1073/pnas.1601006113
Civitello DJ, Cohen J, Fatima H, Halstead NT, Liriano J, McMahon TA, Rohr JR (2015)
Biodiversity inhibits parasites: broad evidence for the dilution effect
.
Proceedings of the National Academy of Sciences
112
(
28
):
8667
‑
8671
. https://doi.org/10.1073/pnas.1506279112
Clark AT, Barry KE, Roscher C, Buchmann T, Loreau M, Harpole WS (2019)
How to estimate complementarity and selection effects from an incomplete sample of species
.
Methods in Ecology and Evolution
10
(
12
):
2141
‑
2152
. https://doi.org/10.1111/2041-210X.13285
Courty P, Buée M, Diedhiou AG, Frey-Klett P, Le Tacon F, Rineau F, Turpault M, Uroz S, Garbaye J (2010)
The role of ectomycorrhizal communities in forest ecosystem processes: New perspectives and emerging concepts
.
Soil Biology and Biochemistry
42
(
5
):
679
‑
698
. https://doi.org/10.1016/j.soilbio.2009.12.006
Craig ME, Turner BL, Liang C, Clay K, Johnson DJ, Phillips RP (2018)
Tree mycorrhizal type predicts within‐site variability in the storage and distribution of soil organic matter
.
Global Change Biology
24
(
8
):
3317
‑
3330
. https://doi.org/10.1111/gcb.14132
Craven D, Eisenhauer N, Pearse WD, Hautier Y, Isbell F, Roscher C, Byun C (2018)
Multiple facets of biodiversity drive the diversity-stability relationship
.
Nature Ecology & Evolution
2
(
10
):
1579
‑
1587
. https://doi.org/10.1038/s41559-018-0647-7
Craven D, Winter M, Hotzel K, Gaikwad J, Eisenhauer N, Hohmuth M, Wirth C (2019)
Evolution of interdisciplinarity in biodiversity science
.
Ecology and Evolution
9
(
12
):
6744
‑
6755
. https://doi.org/10.1002/ece3.5244
Crowther TW, Glick HB, Covey KR, Bettigole C, Maynard DS, Thomas SM, Tuanmu MN (2015)
Mapping tree density at a global scale
.
Nature
525
(
7568
):
201
‑
205
. https://doi.org/10.1038/nature14967
De Mazancourt C, Isbell F, Larocque A, Berendse F, De Luca E, Grace JB, Tilman D (2013)
Predicting ecosystem stability from community composition and biodiversity
.
Ecology Letters
16
(
5
):
617
‑
625
. https://doi.org/10.1111/ele.12088
Díaz S, Settele J, Brondízio E, Ngo H, Agard J, Arneth A, Balvanera P, Brauman K, Butchart SM, Chan KA, Garibaldi L, Ichii K, Liu J, Subramanian S, Midgley G, Miloslavich P, Molnár Z, Obura D, Pfaff A, Polasky S, Purvis A, Razzaque J, Reyers B, Chowdhury RR, Shin Y, Visseren-Hamakers I, Willis K, Zayas C (2019)
Pervasive human-driven decline of life on Earth points to the need for transformative change
.
Science
366
(
6471
). https://doi.org/10.1126/science.aax3100
Duffy JE, Godwin CM, Cardinale BJ (2017)
Biodiversity effects in the wild are common and as strong as key drivers of productivity
.
Nature
549
(
7671
):
261
‑
264
. https://doi.org/10.1038/nature23886
Dumbrell AJ, Ashton PD, Aziz N, Feng G, Nelson M, Dytham C, Helgason T (2011)
Distinct seasonal assemblages of arbuscular mycorrhizal fungi revealed by massively parallel pyrosequencing
.
New Phytologist
190
(
3
):
794
‑
804
. https://doi.org/10.1111/j.1469-8137.2010.03636.x
Eisenhauer N, Scheu S (2008)
Earthworms as drivers of the competition between grasses and legumes
.
Soil Biology and Biochemistry
40
(
10
):
2650
‑
2659
. https://doi.org/10.1016/j.soilbio.2008.07.010
Eisenhauer N, König S, Sabais AC, Renker C, Buscot F, Scheu S (2009)
Impacts of earthworms and arbuscular mycorrhizal fungi (Glomus intraradices) on plant performance are not interrelated
.
Soil Biology and Biochemistry
41
(
3
):
561
‑
567
. https://doi.org/10.1016/j.soilbio.2008.12.017
Eisenhauer N, Beßler H, Engels C, Gleixner G, Habekost M, Milcu A, Partsch S, Sabais ACW, Scherber C, Steinbeiss S, Weigelt A, Weisser WW, Scheu S (2010)
Plant diversity effects on soil microorganisms support the singular hypothesis
.
Ecology
91
(
2
):
485
‑
496
. https://doi.org/10.1890/08-2338.1
Eisenhauer N (2012)
Aboveground-belowground interactions as a source of complementarity effects in biodiversity experiments
.
Plant and Soil
351
(
1-2
):
1
‑
22
. https://doi.org/10.1007/s11104-011-1027-0
Eisenhauer N, Reich PB, Isbell F (2012a)
Decomposer diversity and identity influence plant diversity effects on ecosystem functioning
.
Ecology
93
(
10
):
2227
‑
2240
. https://doi.org/10.1890/11-2266.1
Eisenhauer N, Reich PB, Scheu S (2012b)
Increasing plant diversity effects on productivity with time due to delayed soil biota effects on plants
.
Basic and Applied Ecology
13
(
7
):
571
‑
578
. https://doi.org/10.1016/j.baae.2012.09.002
Eisenhauer N, Dobies T, Cesarz S, Hobbie SE, Meyer RJ, Worm K, Reich PB (2013)
Plant diversity effects on soil food webs are stronger than those of elevated CO2 and N deposition in a long-term grassland experiment
.
Proceedings of the National Academy of Sciences
110
(
17
):
6889
‑
6894
. https://doi.org/10.1073/pnas.1217382110
Eisenhauer N, Barnes A, Cesarz S, Craven D, Ferlian O, Gottschall F, Hines J, Sendek A, Siebert J, Thakur M, Türke M (2016)
Biodiversity-ecosystem function experiments reveal the mechanisms underlying the consequences of biodiversity change in real world ecosystems
.
Journal of Vegetation Science
27
(
5
):
1061
‑
1070
. https://doi.org/10.1111/jvs.12435
Eisenhauer N, Lanoue A, Strecker T, Scheu S, Steinauer K, Thakur MP, Mommer L (2017)
Root biomass and exudates link plant diversity with soil bacterial and fungal biomass
.
Scientific Reports
7
(
1
):
1
‑
8
. https://doi.org/10.1038/srep44641
Eisenhauer N (2018a)
Aboveground-belowground interactions drive the relationship between plant diversity and ecosystem function
.
Research Ideas and Outcomes
4
:
23688
. https://doi.org/10.3897/rio.4.e23688
Eisenhauer N (2018b)
Artenverlust schmälert Ökosystemleistungen
.
Ökologie & Landbau
2|2018
:
50
‑
51
.
Eisenhauer N, Türke M (2018)
From climate chambers to biodiversity chambers
.
Frontiers in Ecology and the Environment
16
(
3
):
136
‑
137
. https://doi.org/10.1002/fee.1784
Eisenhauer N, Vogel A (2018)
Artenvielfalt verbessert die Funktionsweise von Ökosystemen
.
Bionachrichten, Ausgabe
36
‑
37
.
Eisenhauer N, Herrmann S, Hines J, Buscot F, Siebert J, Thakur MP (2018a)
The dark side of animal phenology
.
Trends in Ecology & Evolution
33
(
12
):
898
‑
901
. https://doi.org/10.1016/j.tree.2018.09.010
Eisenhauer N, Hines J, Isbell F, Plas F, Hobbie SE, Kazanski CE, Vogel A (2018b)
Plant diversity maintains multiple soil functions in future environments
.
ELife
7
:
41228
. https://doi.org/10.7554/eLife.41228
Eisenhauer N, Bonkowski M, Brose U, Buscot F, Durka W, Ebeling A, Jesch A (2019a)
Biotic interactions, community assembly, and eco-evolutionary dynamics as drivers of long-term biodiversity-ecosystem functioning relationships
.
Research Ideas and Outcomes: The Open Science Journal
5
:
47042
. https://doi.org/10.3897/rio.5.e47042
Eisenhauer N, Schielzeth H, Barnes AD, Barry K, Bonn A, Brose U, Ferlian O (2019b)
A multitrophic perspective on biodiversity-ecosystem functioning research
.
Advances in Ecological Research
61
:
1
. https://doi.org/10.1016/bs.aecr.2019.06.001
European Commission (2019)
Stepping up EU Action to Protect and Restore the World’s Forests
.
COM(2019)
352
:
22
.
Fang M, Ju W, Zhan W, Cheng T, Qiu F, Wang J (2017)
A new spectral similarity water index for the estimation of leaf water content from hyperspectral data of leaves
.
Remote Sensing of Environment
196
:
13
‑
27
. https://doi.org/10.1016/j.rse.2017.04.029
Ferlian O, Wirth C, Eisenhauer N (2017)
Leaf and root C-to-N ratios are poor predictors of soil microbial biomass C and respiration across 32 tree species
.
Pedobiologia
65
:
16
‑
23
. https://doi.org/10.1016/j.pedobi.2017.06.005
Ferlian O, Biere A, Bonfante P, Buscot F, Eisenhauer N, Fernandez I, Hause B, Herrmann S, Krajinski-Barth F, Meier I, Pozo M, Rasmann S, Rillig M, Tarkka M, van Dam N, Wagg C, Martinez-Medina A (2018a)
Growing Research Networks on Mycorrhizae for Mutual Benefits
.
Trends in Plant Science
23
(
11
):
975
‑
984
. https://doi.org/10.1016/j.tplants.2018.08.008
Ferlian O, Cesarz S, Craven D, Hines J, Barry K, Bruelheide H, Buscot F, Haider S, Heklau H, Herrmann S, Kühn P, Pruschitzki U, Schädler M, Wagg C, Weigelt A, Wubet T, Eisenhauer N (2018b)
Mycorrhiza in tree diversity–ecosystem function relationships: conceptual framework and experimental implementation
.
Ecosphere
9
(
5
). https://doi.org/10.1002/ecs2.2226
Finlay RD (2004)
Mycorrhizal fungi and their multifunctional roles
.
Mycologist
18
(
2
):
91
‑
96
. https://doi.org/10.1017/S0269915X04002058
Fischer C, Leimer S, Roscher C, Ravenek J, Kroon H, Kreutziger Y, Hildebrandt A (2019)
Plant species richness and functional groups have different effects on soil water content in a decade‐long grassland experiment
.
Journal of Ecology
107
(
1
):
127
‑
141
. https://doi.org/10.1111/1365-2745.13046
Fornara DA, Tilman D (2008)
Plant functional composition influences rates of soil carbon and nitrogen accumulation
.
Journal of Ecology
96
(
2
):
314
‑
322
. https://doi.org/10.1111/j.1365-2745.2007.01345.x
Gauzens B, Barnes A, Giling DP, Hines J, Jochum M, Lefcheck JS, Brose U (2019)
fluxweb: An R package to easily estimate energy fluxes in food webs
.
Methods in Ecology and Evolution
10
(
2
):
270
‑
279
. https://doi.org/10.1111/2041-210X.13109
Gellie NJ, Breed MF, Mortimer PE, Harrison RD, Xu J, Lowe AJ (2018)
Networked and embedded scientific experiments will improve restoration outcomes
.
Frontiers in Ecology and the Environment
16
(
5
):
288
‑
294
. https://doi.org/10.1002/fee.1810
Gockele A, Weigelt A, Gessler A, Scherer-Lorenzen M (2014)
Quantifying resource use complementarity in grassland species: a comparison of different nutrient tracers
.
Pedobiologia
57
(
4-6
):
251
‑
256
. https://doi.org/10.1016/j.pedobi.2014.09.001
Gonzalez A, Germain RM, Srivastava DS, Filotas E, Dee LE, Gravel D, Loreau M (2020)
Scaling‐up biodiversity‐ecosystem functioning research
.
Ecology Letters
23
(
4
):
757
‑
776
. https://doi.org/10.1111/ele.13456
Grace JB, Anderson TM, Seabloom EW, Borer ET, Adler PB, Harpole WS, Bakker JD (2016)
Integrative modelling reveals mechanisms linking productivity and plant species richness
.
Nature
529
(
7586
):
390
‑
393
. https://doi.org/10.1038/nature16524
Grossiord C, Granier A, Ratcliffe S, Bouriaud O, Bruelheide H, Chećko E, Forrester DI, Dawud SM, Finér L, Pollastrini M, Scherer-Lorenzen M, Valladares F, Bonal D, Gessler A (2014)
Tree diversity does not always improve resistance of forest ecosystems to drought
.
Proceedings of the National Academy of Sciences
111
(
41
):
14812
‑
14815
. https://doi.org/10.1073/pnas.1411970111
Grossman JJ, Vanhellemont M, Barsoum N, Bauhus J, Bruelheide H, Castagneyrol B, Cavender-Bares J, Eisenhauer N, Hector A (2018)
Synthesis and future research directions linking tree diversity to growth, survival, and damage in a global network of tree diversity experiments
.
Environmental and Experimental Botany
152
:
68
‑
89
. https://doi.org/10.1016/j.envexpbot.2017.12.015
Guerrero-Ramírez N, Craven D, Reich P, Ewel J, Isbell F, Koricheva J, Parrotta J, Auge H, Erickson H, Forrester D, Hector A, Joshi J, Montagnini F, Palmborg C, Piotto D, Potvin C, Roscher C, van Ruijven J, Tilman D, Wilsey B, Eisenhauer N (2017)
Diversity-dependent temporal divergence of ecosystem functioning in experimental ecosystems
.
Nature Ecology & Evolution
1
(
11
):
1639
‑
1642
. https://doi.org/10.1038/s41559-017-0325-1
Guerrero-Ramírez NR, Craven D, Reich PB, Wagg C, Ciobanu M, Eisenhauer N (2019)
Diversity‐dependent plant-soil feedbacks underlie long‐term plant diversity effects on primary productivity
.
Ecosphere
10
(
4
):
02704
. https://doi.org/10.1002/ecs2.2704
Guiz J, Ebeling A, Eisenhauer N, Hacker N, Hertzog L, Oelmann Y, Hillebrand H (2018)
Interspecific competition alters leaf stoichiometry in 20 grassland species
.
Oikos
127
(
7
):
903
‑
914
. https://doi.org/10.1111/oik.04907
Heklau H, Schindler N, Buscot F, Eisenhauer N, Ferlian O, Prada Salcedo LD, Bruelheide H (2021)
Mixing tree species associated with arbuscular or ectotrophic mycorrhizae reveals dual mycorrhization and interactive effects on the fungal partners
.
Ecology and Evolution
00,1
:
17
. https://doi.org/10.1002/ece3.7437
Herrmann S, Grams TE, Tarkka MT, Angay O, Bacht M, Bönn M, Mailander S (2016)
Endogenous rhythmic growth, a trait suitable for the study of interplays between multitrophic interactions and tree development
.
Perspectives in Plant Ecology, Evolution and Systematics
19
:
40
‑
48
. https://doi.org/10.1016/j.ppees.2016.02.003
Hines J, Putten WH, de Deyn GB, Wagg C, Voigt W, Mulder C, Birkhofer K (2015)
Towards an integration of biodiversity-ecosystem functioning and food web theory to evaluate relationships between multiple ecosystem services
.
Advances in ecological research
.
53
.
Academic Press
https://doi.org/10.1016/bs.aecr.2015.09.001
Hoeksema JD, Chaudhary VB, Gehring CA, Johnson NC, Karst J, Koide RT, Wilson GW (2010)
A meta‐analysis of context‐dependency in plant response to inoculation with mycorrhizal fungi
.
Ecology Letters
13
(
3
):
394
‑
407
. https://doi.org/10.1111/j.1461-0248.2009.01430.x
Horton TR (2015)
Mycorrhizal Networks
.
Springer
https://doi.org/10.1007/978-94-017-7395-9
Huang Y, Chen Y, Castro-Izaguirre N, Baruffol M, Brezzi M, Lang A, Liu X (2018)
Impacts of species richness on productivity in a large-scale subtropical forest experiment
.
Science
362
(
6410
):
80
‑
83
. https://doi.org/10.1126/science.aat6405
Hutchinson GE (1978)
An Introduction to Population Biology
.
Yale Univ. Press
Hutchison C, Gravel D, Guichard F, Potvin C (2018)
Effect of diversity on growth, mortality, and loss of resilience to extreme climate events in a tropical planted forest experiment
.
Scientific Reports
8
(
1
):
1
‑
10
. https://doi.org/10.1038/s41598-018-33670-x
Isbell F, Calcagno V, Hector A, Connolly J, Harpole WS, Reich PB, Loreau M (2011)
High plant diversity is needed to maintain ecosystem services
.
Nature
477
(
7363
):
199
‑
202
. https://doi.org/10.1038/nature10282
Isbell F, Craven D, Connolly J, Loreau M, Schmid B, Beierkuhnlein C, Ebeling A (2015)
Biodiversity increases the resistance of ecosystem productivity to climate extremes
.
Nature
526
(
7574
):
574
‑
577
. https://doi.org/10.1038/nature15374
Isbell F, Adler P, Eisenhauer N, Fornara D, Kimmel K, Kremen C, Letourneau D, Liebman M, Polley HW, Quijas S, Scherer‐Lorenzen M (2017a)
Benefits of increasing plant diversity in sustainable agroecosystems
.
Journal of Ecology
105
(
4
):
871
‑
879
. https://doi.org/10.1111/1365-2745.12789
Isbell F, Gonzalez A, Loreau M, Cowles J, Díaz S, Hector A, Mace G, Wardle D, O'Connor M, Duffy JE, Turnbull L, Thompson P, Larigauderie A (2017b)
Linking the influence and dependence of people on biodiversity across scales
.
Nature
546
(
7656
):
65
‑
72
. https://doi.org/10.1038/nature22899
Jansa J, Mozafar A, Frossard E (2005)
Phosphorus acquisition strategies within arbuscular mycorrhizal fungal community of a single field site
.
Plant and Soil
276
(
1-2
):
163
‑
176
. https://doi.org/10.1007/s11104-005-4274-0
Jeffries P, Gianinazzi S, Perotto S, Turnau K, Barea JM (2003)
The contribution of arbuscular mycorrhizal fungi in sustainable maintenance of plant health and soil fertility
.
Biology and Fertility of Soils
37
(
1
):
1
‑
16
. https://doi.org/10.1007/s00374-002-0546-5
Johnson DJ, Beaulieu WT, Bever JD, Clay K (2012)
Conspecific negative density dependence and forest diversity
.
Science
336
(
6083
):
904
‑
907
. https://doi.org/10.1126/science.1220269
Johnson NC, Graham JH, Smith FA (1997)
Functioning of mycorrhizal associations along the mutualism-parasitism continuum
.
The New Phytologist
135
(
4
):
575
‑
585
. https://doi.org/10.1046/j.1469-8137.1997.00729.x
Johnson NC, Graham JH (2013)
The continuum concept remains a useful framework for studying mycorrhizal functioning
.
Plant and Soil
363
(
1
):
411
‑
419
. https://doi.org/10.1007/s11104-012-1406-1
Jousset A, Schmid B, Scheu S, Eisenhauer N (2011)
Genotypic richness and dissimilarity opposingly affect ecosystem functioning
.
Ecology Letters
14
(
6
):
537
‑
545
. https://doi.org/10.1111/j.1461-0248.2011.01613.x
Kattge J, Díaz S, Lavorel S, Prentice IC, Leadley P, Bönisch G, Garnier E, Westoby M, Reich PB, Wright IJ, Cornelissen JHC, Violle C, Harrison SP, Van Bodegom PM, Reichstein M, Enquist BJ, Soudzilovskaia NA, Ackerly DD, Anand M, Atkin O, Bahn M, Baker TR, Baldocchi D, Bekker R, Blanco CC, Blonder B, Bond WJ, Bradstock R, Bunker DE, Casanoves F, Cavender-Bares J, Chambers JQ, Chapin III FS, Chave J, Coomes D, Cornwell WK, Craine JM, Dobrin BH, Duarte L, Durka W, Elser J, Esser G, Estiarte M, Fagan WF, Fang J, Fernández-Méndez F, Fidelis A, Finegan B, Flores O, Ford H, Frank D, Freschet GT, Fyllas NM, Gallagher RV, Green WA, Gutierrez AG, Hickler T, Higgins SI, Hodgson JG, Jalili A, Jansen S, Joly CA, Kerkhoff AJ, Kirkup D, Kitajima K, Kleyer M, Klotz S, Knops JMH, Kramer K, Kühn I, Kurokawa H, Laughlin D, Lee TD, Leishman M, Lens F, Lenz T, Lewis SL, Lloyd J, Llusià J, Louault F, Ma S, Mahecha MD, Manning P, Massad T, Medlyn BE, Messier J, Moles AT, Müller SC, Nadrowski K, Naeem S, Niinemets Ü, Nöllert S, Nüske A, Ogaya R, Oleksyn J, Onipchenko VG, Onoda Y, Ordoñez J, Overbeck G, Ozinga WA, Patiño S, Paula S, Pausas JG, Peñuelas J, Phillips OL, Pillar V, Poorter H, Poorter L, Poschlod P, Prinzing A, Proulx R, Rammig A, Reinsch S, Reu B, Sack L, Salgado-Negret B, Sardans J, Shiodera S, Shipley B, Siefert A, Sosinski E, Soussana J-, Swaine E, Swenson N, Thompson K, Thornton P, Waldram M, Weiher E, White M, White S, Wright SJ, Yguel B, Zaehle S, Zanne AE, Wirth C (2011)
TRY - a global database of plant traits
.
Global Change Biology
17
(
9
):
2905
‑
2935
. https://doi.org/10.1111/j.1365-2486.2011.02451.x
Keller AB, Phillips RP (2019)
Relationship Between Belowground Carbon Allocation and Nitrogen Uptake in Saplings Varies by Plant Mycorrhizal Type
.
Frontiers in Forests and Global Change
2
:
81
. https://doi.org/10.3389/ffgc.2019.00081
Klein T, Siegwolf RT, Körner C (2016)
Belowground carbon trade among tall trees in a temperate forest
.
Science
352
(
6283
):
342
‑
344
. https://doi.org/10.1126/science.aad6188
Klironomos JN, McCune J, Hart M, Neville J (2000)
The influence of arbuscular mycorrhizae on the relationship between plant diversity and productivity
.
Ecology Letters
3
(
2
):
137
‑
141
. https://doi.org/10.1046/j.1461-0248.2000.00131.x
Koide RT (2000)
Functional complementarity in the arbuscular mycorrhizal symbiosis
.
New Phytologist
147
(
2
):
233
‑
235
. https://doi.org/10.1046/j.1469-8137.2000.00710.x
Kouno K, Tuchiya Y, Ando T (1995)
Measurement of soil microbial biomass phosphorus by an anion exchange membrane method
.
Soil Biology and Biochemistry
27
(
10
):
1353
‑
1357
. https://doi.org/10.1016/0038-0717(95)00057-L
Kulmatiski A, Beard KH, Heavilin J (2012)
Plant-soil feedbacks provide an additional explanation for diversity-productivity relationships
.
Proceedings of the Royal Society B: Biological Sciences
279
(
1740
):
3020
‑
3026
. https://doi.org/10.1098/rspb.2012.0285
Lange M, Eisenhauer N, Sierra C, Bessler H, Engels C, Griffiths RI, Steinbeiss S (2015)
Plant diversity drives soil carbon storage by increased soil microbial activity
.
Nature Communications
6
:
6707
. https://doi.org/10.1038/ncomms7707
Leake J, Johnson D, Donnelly D, Muckle G, Boddy L, Read D (2004)
Networks of power and influence: the role of mycorrhizal mycelium in controlling plant communities and agroecosystem functioning
.
Canadian Journal of Botany
82
(
8
):
1016
‑
1045
. https://doi.org/10.1139/b04-060
Lefcheck JS, Byrnes JE, Isbell F, Gamfeldt L, Griffin JN, Eisenhauer N, Duffy JE (2015)
Biodiversity enhances ecosystem multifunctionality across trophic levels and habitats
.
Nature Communications
6
(
1
):
1
‑
7
. https://doi.org/10.1038/ncomms7936
Lindahl BD, Ihrmark K, Boberg J, Trumbore SE, Högberg P, Stenlid J, Finlay RD (2007)
Spatial separation of litter decomposition and mycorrhizal nitrogen uptake in a boreal forest
.
New Phytologist
173
(
3
):
611
‑
620
. https://doi.org/10.1111/j.1469-8137.2006.01936.x
Lin G, McCormack ML, Ma C, Guo D (2017)
Similar below‐ground carbon cycling dynamics but contrasting modes of nitrogen cycling between arbuscular mycorrhizal and ectomycorrhizal forests
.
New Phytologist
213
(
3
):
1440
‑
1451
. https://doi.org/10.1111/nph.14206
Liu H, Macdonald CA, Cook J, Anderson IC, Singh BK (2019)
An Ecological Loop: Host Microbiomes across Multitrophic Interactions
.
Trends in Ecology & Evolution
https://doi.org/10.1016/j.tree.2019.07.011
Liu X, Trogisch S, He J, Niklaus P, Bruelheide H, Tang Z, Erfmeier A, Scherer-Lorenzen M, Pietsch K, Yang B, Kühn P, Scholten T, Huang Y, Wang C, Staab M, Leppert K, Wirth C, Schmid B, Ma K (2018)
Tree species richness increases ecosystem carbon storage in subtropical forests
.
Proceedings of the Royal Society B: Biological Sciences
285
(
1885
). https://doi.org/10.1098/rspb.2018.1240
Loreau M, Hector A (2001)
Partitioning selection and complementarity in biodiversity experiments
.
Nature
412
(
6842
):
72
‑
76
. https://doi.org/10.1038/35083573
Loreau M, Naeem S, Inchausti P, Bengtsson J, Grime JP, Hector A, Tilman D (2001)
Biodiversity and ecosystem functioning: current knowledge and future challenges
.
Science
294
(
5543
):
804
‑
808
. https://doi.org/10.1126/science.1064088
Luo S, Schmid B, De Deyn GB, Yu S (2018)
Soil microbes promote complementarity effects among co‐existing trees through soil nitrogen partitioning
.
Functional Ecology
32
(
7
):
1879
‑
1889
. https://doi.org/10.1111/1365-2435.13109
Maestre FT, Eisenhauer N (2019)
Recommendations for establishing global collaborative networks in soil ecology
.
Soil Organisms
91
(
3
):
73
. https://doi.org/10.25674/so91iss3pp73
Maherali H, Klironomos JN (2007)
Influence of phylogeny on fungal community assembly and ecosystem functioning
.
Science
316
(
5832
):
1746
‑
1748
. https://doi.org/10.1126/science.1143082
Ma Z, Guo D, Xu X, Lu M, Bardgett RD, Eissenstat DM, Hedin LO (2018)
Evolutionary history resolves global organization of root functional traits
.
Nature
555
(
7694
):
94
‑
97
. https://doi.org/10.1038/nature25783
McLaughlin MJ, Alston AM, Martin JK (1986)
Measurement of phosphorus in the soil microbial biomass: a modified procedure for field soils
.
Soil Biology and Biochemistry
18
(
4
):
437
‑
443
. https://doi.org/10.1016/0038-0717(86)90050-7
Meyer ST, Ptacnik R, Hillebrand H, Bessler H, Buchmann N, Ebeling A, Klein AM (2018)
Biodiversity-multifunctionality relationships depend on identity and number of measured functions
.
Nature Ecology & Evolution
2
(
1
):
44
‑
49
. https://doi.org/10.1038/s41559-017-0391-4
Mueller KE, Tilman D, Fornara DA, Hobbie SE (2013)
Root depth distribution and the diversity-productivity relationship in a long‐term grassland experiment
.
Ecology
94
(
4
):
787
‑
793
. https://doi.org/10.1890/12-1399.1
Naeem S, Thompson LJ, Lawler SP, Lawton JH, Woodfin RM (1994)
Declining biodiversity can alter the performance of ecosystems
.
Nature
368
(
6473
):
734
‑
737
. https://doi.org/10.1038/368734a0
Oram N, Ravenek J, Barry K, Weigelt A, Chen H, Gessler A, Gockele A, de Kroon H, van der Paauw JW, Scherer-Lorenzen M, Smit-Tiekstra A, van Ruijven J, Mommer L (2017)
Below-ground complementarity effects in a grassland biodiversity experiment are related to deep-rooting species
.
Journal of Ecology
106
(
1
):
265
‑
277
. https://doi.org/10.1111/1365-2745.12877
Pan Y, Birdsey RA, Fang J, Houghton R, Kauppi PE, Kurz WA, Hayes D (2011)
A large and persistent carbon sink in the world’s forests
.
Science
333
(
6045
):
988
‑
993
. https://doi.org/10.1126/science.1201609
Paquette A, Hector A, Castagneyrol B, Vanhellemont M, Koricheva J, Scherer-Lorenzen M, Verheyen K, Eisenhauer N T (2018)
A million and more trees for science
.
Nature Ecology & Evolution
2
(
5
):
763
‑
766
. https://doi.org/10.1038/s41559-018-0544-0
Peterson RL, Massicotte HB, Melville LH (2004)
Mycorrhizas: Anatomy and Cell Biology
.
NRC Research Press
https://doi.org/10.1017/S0953756205213126
Plett JM, Martin F (2011)
Blurred boundaries: lifestyle lessons from ectomycorrhizal fungal genomes
.
Trends in Genetics
27
(
1
):
14
‑
22
. https://doi.org/10.1016/j.tig.2010.10.005
Powell JR, Parrent JL, Hart MM, Klironomos JN, Rillig MC, Maherali H (2009)
Phylogenetic trait conservatism and the evolution of functional trade-offs in arbuscular mycorrhizal fungi
.
Proceedings of the Royal Society B: Biological Sciences
276
(
1676
):
4237
‑
4245
. https://doi.org/10.1098/rspb.2009.1015
Ratcliffe S, Liebergesell M, Ruiz-Benito P, Madrigal González J, Muñoz Castañeda J, Kändler G, Lehtonen A, Dahlgren J, Kattge J, Peñuelas J, Zavala M, Wirth C (2015)
Modes of functional biodiversity control on tree productivity across the European continent
.
Global Ecology and Biogeography
25
(
3
):
251
‑
262
. https://doi.org/10.1111/geb.12406
Ratcliffe S, Wirth C, Jucker T, van der Plas F, Scherer-Lorenzen M, Verheyen K, Allan E, Benavides R, Bruelheide H, Ohse B, Paquette A, Ampoorter E, Bastias C, Bauhus J, Bonal D, Bouriaud O, Bussotti F, Carnol M, Castagneyrol B, Chećko E, Dawud SM, Wandeler HD, Domisch T, Finér L, Fischer M, Fotelli M, Gessler A, Granier A, Grossiord C, Guyot V, Haase J, Hättenschwiler S, Jactel H, Jaroszewicz B, Joly F, Kambach S, Kolb S, Koricheva J, Liebersgesell M, Milligan H, Müller S, Muys B, Nguyen D, Nock C, Pollastrini M, Purschke O, Radoglou K, Raulund-Rasmussen K, Roger F, Ruiz-Benito P, Seidl R, Selvi F, Seiferling I, Stenlid J, Valladares F, Vesterdal L, Baeten L (2017)
Biodiversity and ecosystem functioning relations in European forests depend on environmental context
.
Ecology Letters
20
(
11
):
1414
‑
1426
. https://doi.org/10.1111/ele.12849
Read DJ, Perez‐Moreno J (2003)
Mycorrhizas and nutrient cycling in ecosystems-a journey towards relevance?
New Phytologist
157
(
3
):
475
‑
492
. https://doi.org/10.1046/j.1469-8137.2003.00704.x
Reich PB, Tilman D, Isbell F, Mueller K, Hobbie SE, Flynn DF, Eisenhauer N (2012)
Impacts of biodiversity loss escalate through time as redundancy fades
.
Science
336
(
6081
):
589
‑
592
. https://doi.org/10.1126/science.1217909
Reinhart KO, Anacker BL (2014)
More closely related plants have more distinct mycorrhizal communities
.
AoB Plants
6
https://doi.org/10.1093/aobpla/plu051
Sagan V, Maimaitijiang M, Sidike P, Eblimit K, Peterson KT, Hartling S, Ward R (2019)
Uav-based high resolution thermal imaging for vegetation monitoring, and plant phenotyping using ici 8640 p, flir vue pro r 640, and thermomap cameras
.
Remote Sensing
11
(
3
):
330
. https://doi.org/10.3390/rs11030330
Salmon Y, Li X, Yang B, Ma K, Siegwolf RT, Schmid B (2018)
Surrounding species diversity improves subtropical seedlings’ carbon dynamics
.
Ecology and Evolution
8
(
14
):
7055
‑
7067
. https://doi.org/10.1002/ece3.4225
Scherber C, Eisenhauer N, Weisser W, Schmid B, Voigt W, Fischer M, Schulze E, Roscher C, Weigelt A, Allan E, Beßler H, Bonkowski M, Buchmann N, Buscot F, Clement L, Ebeling A, Engels C, Halle S, Kertscher I, Klein A, Koller R, König S, Kowalski E, Kummer V, Kuu A, Lange M, Lauterbach D, Middelhoff C, Migunova V, Milcu A, Müller R, Partsch S, Petermann J, Renker C, Rottstock T, Sabais A, Scheu S, Schumacher J, Temperton V, Tscharntke T (2010)
Bottom-up effects of plant diversity on multitrophic interactions in a biodiversity experiment
.
Nature
468
(
7323
):
553
‑
556
. https://doi.org/10.1038/nature09492
Schmidt A, Hines J, T&uuml r, M. B, Schädler M, Weigelt A, Eisenhauer N (2021)
The iDiv Ecotron-a flexible research platform for multitrophic biodiversity research
.
Ecology and Evolution
11
(
21
):
15174
‑
15190
. https://doi.org/10.1002/ece3.8198
Schmidt MW, Torn MS, Abiven S, Dittmar T, Guggenberger G, Janssens IA, Nannipieri P (2011)
Persistence of soil organic matter as an ecosystem property
.
Nature
478
(
7367
):
49
‑
56
. https://doi.org/10.1038/nature10386
Schnitzer SA, Klironomos JN, HilleRisLambers J, Kinkel LL, Reich PB, Xiao K, Van Nes EH (2011)
Soil microbes drive the classic plant diversity-productivity pattern
.
Ecology
92
(
2
):
296
‑
303
. https://doi.org/10.1890/10-0773.1
Schrumpf M, Schulze ED, Kaiser K, Schumacher J (2011)
How accurately can soil organic carbon stocks and stock changes be quantified by soil inventories?
Biogeosciences
8
(
5
):
1193
‑
1212
. https://doi.org/10.5194/bg-8-1193-2011
Schulze ED, Mooney H (1994)
Ecosystem Function of Biodiversity: A Summary
.
Springer Science & Business Media
https://doi.org/10.1007/978-3-642-58001-7_24
Schwarz B, Barnes AD, Thakur MP, Brose U, Ciobanu M, Reich PB, Eisenhauer N (2017)
Warming alters energetic structure and function but not resilience of soil food webs
.
Nature Climate Change
7
(
12
):
895
‑
900
. https://doi.org/10.1038/s41558-017-0002-z
Selosse MA, Richard F, He X, Simard SW (2006)
Mycorrhizal networks: des liaisons dangereuses?
Trends in Ecology & Evolution
21
(
11
):
621
‑
628
. https://doi.org/10.1016/j.tree.2006.07.003
Sendek A, Karakoç C, Wagg C, Domínguez-Begines J, do Couto GM, van der Heijden MA, Naz AA, Lochner A, Chatzinotas A, Klotz S, Gómez-Aparicio L, Eisenhauer N (2019)
Drought modulates interactions between arbuscular mycorrhizal fungal diversity and barley genotype diversity
.
Scientific Reports
9
(
1
). https://doi.org/10.1038/s41598-019-45702-1
Simard SW, Perry DA, Jones MD, Myrold DD, Durall DM, Molina R (1997)
Net transfer of carbon between ectomycorrhizal tree species in the field
.
Nature
388
(
6642
):
579
‑
582
. https://doi.org/10.1038/41557
Simard SW, Durall DM (2004)
Mycorrhizal networks: a review of their extent, function, and importance
.
Canadian Journal of Botany
82
(
8
):
1140
‑
1165
. https://doi.org/10.1139/b04-116
Smith FA, Jakobsen I, Smith SE (2000)
Spatial differences in acquisition of soil phosphate between two arbuscular mycorrhizal fungi in symbiosis with Medicago truncatula
.
New Phytologist
147
(
2
):
357
‑
366
. https://doi.org/10.1046/j.1469-8137.2000.00695.x
Smith SE, Read DJ (2008)
Mycorrhizal symbiosis
.
Academic Press
https://doi.org/10.1016/B978-0-12-370526-6.X5001-6
Soliveres S, Van Der Plas F, Manning P, Prati D, Gossner MM, Renner SC, Birkhofer K (2016)
Biodiversity at multiple trophic levels is needed for ecosystem multifunctionality
.
Nature
536
(
7617
):
456
‑
459
. https://doi.org/10.1038/nature19092
Soudzilovskaia N, van Bodegom P, Terrer C, Zelfde Mv, McCallum I, Luke McCormack M, Fisher J, Brundrett M, de Sá NC, Tedersoo L (2019)
Global mycorrhizal plant distribution linked to terrestrial carbon stocks
.
Nature Communications
10
(
1
). https://doi.org/10.1038/s41467-019-13019-2
Steidinger BS, Crowther TW, Liang J, Van Nuland ME, Werner GD, Reich PB, Herault B (2019)
Climatic controls of decomposition drive the global biogeography of forest-tree symbioses
.
Nature
569
(
7756
):
404
‑
408
. https://doi.org/10.1038/s41586-019-1128-0
Suz LM, Barsoum N, Benham S, Dietrich HP, Fetzer KD, Fischer R, Bidartondo MI (2014)
Environmental drivers of ectomycorrhizal communities in Europe's temperate oak forests
.
Molecular Ecology
23
(
22
):
5628
‑
5644
. https://doi.org/10.1111/mec.12947
Tarnocai C, Canadell JG, Schuur EA, Kuhry P, Mazhitova G, Zimov S (2009)
Soil organic carbon pools in the northern circumpolar permafrost region
.
Global Biogeochemical Cycles
23
(
2
). https://doi.org/10.1029/2008GB003327
Thakur MP, Milcu A, Manning P, Niklaus PA, Roscher C, Power S, Eisenhauer N (2015)
Plant diversity drives soil microbial biomass carbon in grasslands irrespective of global environmental change factors
.
Global Change Biology
21
(
11
):
4076
‑
4085
. https://doi.org/10.1111/gcb.13011
Thakur MP, Reich PB, Hobbie SE, Stefanski A, Rich R, Rice KE, Eisenhauer N (2018)
Reduced feeding activity of soil detritivores under warmer and drier conditions
.
Nature Climate Change
8
(
1
):
75
‑
78
. https://doi.org/10.1038/s41558-017-0032-6
Tobner CM, Paquette A, Reich PB, Gravel D, Messier C (2014)
Advancing biodiversity-ecosystem functioning science using high-density tree-based experiments over functional diversity gradients
.
Oecologia
174
(
3
):
609
‑
621
. https://doi.org/10.1007/s00442-013-2815-4
van der Heijden MG, Klironomos JN, Ursic M, Moutoglis P, Streitwolf-Engel R, Boller T, Sanders IR (1998)
Mycorrhizal fungal diversity determines plant biodiversity, ecosystem variability and productivity
.
Nature
396
(
6706
):
69
‑
72
. https://doi.org/10.1038/23932
van der Heijden MG, Scheublin TR (2007)
Functional traits in mycorrhizal ecology: their use for predicting the impact of arbuscular mycorrhizal fungal communities on plant growth and ecosystem functioning
.
New Phytologist
174
(
2
):
244
‑
250
. https://doi.org/10.1111/j.1469-8137.2007.02041.x
van der Heijden MG, Horton TR (2009)
Socialism in soil? The importance of mycorrhizal fungal networks for facilitation in natural ecosystems
.
Journal of Ecology
97
(
6
):
1139
‑
1150
. https://doi.org/10.1111/j.1365-2745.2009.01570.x
van der Heijden MG, Martin FM, Selosse MA, Sanders IR (2015)
Mycorrhizal ecology and evolution: the past, the present, and the future
.
New Phytologist
205
(
4
):
1406
‑
1423
. https://doi.org/10.1111/nph.13288
van der Plas F, Manning P, Allan E, Scherer-Lorenzen M, Verheyen K, Wirth C, Barbaro L (2016)
Jack-of-all-trades effects drive biodiversity-ecosystem multifunctionality relationships in European forests
.
Nature Communications
7
(
1
):
1
‑
11
. https://doi.org/10.1038/ncomms11109
Verheyen K, Vanhellemont M, Auge H, Baeten L, Baraloto C, Barsoum N, Haase J (2016)
Contributions of a global network of tree diversity experiments to sustainable forest plantations
.
Ambio
45
(
1
):
29
‑
41
. https://doi.org/10.1007/s13280-015-0685-1
Vogelsang KM, Reynolds HL, Bever JD (2006)
Mycorrhizal fungal identity and richness determine the diversity and productivity of a tallgrass prairie system
.
New Phytologist
172
(
3
):
554
‑
562
. https://doi.org/10.1111/j.1469-8137.2006.01854.x
Wagg C, Barendregt C, Jansa J, Heijden MG (2015)
Complementarity in both plant and mycorrhizal fungal communities are not necessarily increased by diversity in the other
.
Journal of Ecology
103
(
5
):
1233
‑
1244
. https://doi.org/10.1111/1365-2745.12452
Wagner D, Eisenhauer N, Cesarz S (2015)
Plant species richness does not attenuate responses of soil microbial and nematode communities to a flood event
.
Soil Biology and Biochemistry
89
:
135
‑
149
. https://doi.org/10.1016/j.soilbio.2015.07.001
Wardle DA, Bardgett RD, Klironomos JN, Setälä H, van Der Putten WH, Wall DH (2004)
Ecological linkages between aboveground and belowground biota
.
Science
304
(
5677
):
1629
‑
1633
. https://doi.org/10.1126/science.1094875
Weisser WW, Roscher C, Meyer ST, Ebeling A, Luo G, Allan E, Eisenhauer N (2017)
Biodiversity effects on ecosystem functioning in a 15-year grassland experiment: Patterns, mechanisms, and open questions
.
Basic and Applied Ecology
23
:
1
‑
73
. https://doi.org/10.1016/j.baae.2017.06.002
Williams LJ, Paquette A, Cavender-Bares J, Messier C, Reich PB (2017)
Spatial complementarity in tree crowns explains overyielding in species mixtures
.
Nature Ecology & Evolution
1
(
4
):
1
‑
7
. https://doi.org/10.1038/s41559-016-0063
Wilson GW, Rice CW, Rillig MC, Springer A, Hartnett DC (2009)
Soil aggregation and carbon sequestration are tightly correlated with the abundance of arbuscular mycorrhizal fungi: results from long‐term field experiments
.
Ecology Letters
12
(
5
):
452
‑
461
. https://doi.org/10.1111/j.1461-0248.2009.01303.x
Wright AJ, Wardle DA, Callaway R, Gaxiola A (2017)
The overlooked role of facilitation in biodiversity experiments
.
Trends in Ecology & Evolution
32
(
5
):
383
‑
390
. https://doi.org/10.1016/j.tree.2017.02.011
Xu S, Eisenhauer N, Ferlian O, Zhang J, Zhou G, Lu X, Zhang D (2020)
Species richness promotes ecosystem carbon storage: evidence from biodiversity-ecosystem functioning experiments
.
Proceedings of the Royal Society B
287
(
1939
):
20202063
. https://doi.org/10.1098/rspb.2020.2063
Xu S, Sayer EJ, Eisenhauer N, Lu X, Wang J, Liu C (2021)
Aboveground litter inputs determine carbon storage across soil profiles: a meta-analysis
.
Plant and Soil
1-16
https://doi.org/10.1007/s11104-021-04881-5

Supplementary material