Droevendaalsesteeg 10
6708 PB Wageningen
The Netherlands
Social
About
As an ecologist I am trained to unravel the complex web of interactions that shape natural and agro-ecosystems. I am interested in interactions between plants, soil biota and soil functioning, and increasingly also in socio-ecological systems thinking.
Biography
Jasper Wubs obtained his MSc (2010) from Utrecht University and PhD (2017) degree at Wageningen University (the Netherlands), where he studied plant-soil biota interactions and how they steer natural plant community dynamics and their use in nature restoration (with Prof. Martijn Bezemer and Prof. Wim van der Putten). Next, he obtained an NWO Rubicon (2018) grant to study how soil microbiomes can be used to improve soil restoration in degraded arable soils in the central Kenyan highlands (with Prof. Johan Six and Dr. Martin Hartmann at ETH Zurich).
In 2021 Jasper returned to the Netherlands to coordinate data collection and analysis within the new IJkcentrum voor de Bodem (https://nioo.knaw.nl/nl/ijkcentrumbodem) as part of the Onder het Maaiveld project (with IUCN, Vlinderstichting, WUR, Centre for Soil Ecology). The project aims to map and benchmark the soil biodiversity of the Netherlands to provide action perspectives for land managers.
Recently, Jasper received a EU MSCA Postdoctoral Fellowship to study soil multifunctionality in relation to the stoichiometry of plants, microbes and soils (MultiSol) and launched his own Research Group on Soils as Complex Adaptive Systems.
The potential for soil microbiomes to assist in the restoration of biological, chemical and physical soil degradation is tremendous, yet very few projects use the whole-microbiome approach. This is potentially an important research gap, because in-situ interactions among members of the microbiome do fundamentally alter the functioning of specific biota and thus the soils they are in.
CV
Employment
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PresentResearch Group Leader at NIOO-KNAW
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2021–2022Postdoctoral Fellow at NIOO-KNAW
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2018–2021Postdoctoral Fellow at ETH Zürich (NWO Rubicon)
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2017–2018Postdoctoral researcher at NIOO-KNAW
Education
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2012–2017PhD Candidate (NIOO/Wageningen University, NWO Biodiversiteit Werkt)
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2007–2010MSc in Biological Sciences (cum laude, Utrecht University)
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2004–2007BSc in Biology (Utrecht University)
Grants
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2022Marie Skłodowska-Curie Actions (MSCA) Postdoctoral Fellowship
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2019British Ecological Society Large Research Grant
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2018NWO Rubicon Fellowship
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2020Thematic Summer School Grant, Innovative Co-Learning for Agriculture-based Solutions Call for Proposals (Ref. CfP 2002), Agropolis Foundation and Biovision Foundation
PhD students
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2022–PresentGijs Gerrits
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2022–PresentMerlijn Schram
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PresentSam Bielen
Publications
Key publications
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Soil inoculation steers restoration of terrestrial ecosystems
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Single introductions of plants and soil biota generate long-term legacies in plant and soil community assembly
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Synthesis on the effectiveness of soil translocation for plant community restoration
Peer-reviewed publications
Fungicide-free management of Alternaria leaf blotch and fruit spot on apple indicates Alternaria spp. as secondary colonizer
The fungal genus Alternaria is a pan-global pathogen of > 100 crops, and is associated with the globally expanding Alternaria leaf blotch in apple (Malus x domestica Borkh.) which leads to severe leaf necrosis, premature defoliation, and large economic losses. Up to date, the epidemiology of many Alternaria species is still not resolved as they can be saprophytic, parasitic or shift between both lifestyles and are also classified as primary pathogen able to infect healthy tissue. We argue that Alternaria spp. does not act as primary pathogen, but only as a necrosis-dependent opportunist. We studied the infection biology of Alternaria spp. under controlled conditions and monitored disease prevalence in real orchards and validated our ideas by applying fungicide-free treatments in 3-years field experiments. Alternaria spp. isolates were not able to induce necroses in healthy tissue, but only when prior induced damages existed. Next, leaf-applied fertilizers, without fungicidal effect, reduced Alternaria-associated symptoms (− 72.7%, SE: ± 2.5%) with the same efficacy as fungicides. Finally, low leaf magnesium, sulphur, and manganese concentrations were consistently linked with Alternaria-associated leaf blotch. Fruit spot incidence correlated positively with leaf blotch, was also reduced by fertilizer treatments, and did not expand during storage unlike other fungus-mediated diseases. Our findings suggest that Alternaria spp. may be a consequence of leaf blotch rather than its primary cause, as it appears to colonize the physiologically induced leaf blotch. Taking into account existing observations that Alternaria infection is connected to weakened hosts, the distinction may appear slight, but is of great significance, as we can now (a) explain the mechanism of how different stresses result in colonization with Alternaria spp. and (b) substitute fungicides for a basic leaf fertilizer. Therefore, our findings can result in significant decreases in environmental costs due to reduced fungicide use, especially if the same mechanism applies to other crops.https://doi.org/10.1038/s41598-023-35448-2Synthesis on the effectiveness of soil translocation for plant community restoration
Many degraded ecosystems need active restoration to conserve biodiversity and re-establish ecosystem function, both highlighted targets of the UN Decade on Ecosystem Restoration and the proposed EU Nature restoration law. Soil translocation, where both plant propagules and their associated soil biota are co-introduced, has increasingly been proposed as a powerful restoration technique for terrestrial ecosystems. However, a synthesis of the effectiveness of this method across ecosystems is lacking.https://doi.org/10.1111/1365-2664.14364
To address how soil translocation affects restoration success, we performed a meta-analysis synthesizing data from 46 field experiments and their respective reference ecosystems in 17 countries across four continents. In each experiment, vegetation composition was recorded in response to soil translocation treatments and the resultant vegetational changes (diversity and composition) were quantified.
We found that soil translocation leads to plant community development further away from the control and more towards the reference plant communities compared with treatments where only plant propagules were introduced. However, the variability of effect sizes among experiments was large, suggesting strong dependence of restoration success on restoration context. We found that restoration success was more likely on loamy soils and when translocation treatments were implemented over larger spatial areas (>180 m2).
Furthermore, we found that restoration success either consistently increased or decreased over time depending on the experiment. Not only is this congruent with positive feedbacks between plant and soil communities driving plant community development, but it also suggests that the composition of the translocated plant and soil communities, and initial starting conditions, are critical for long-term restoration success.
Synthesis and applications. Our analysis highlights soil translocation can be a successful restoration method across a broad range of ecosystems. However, its implementation needs to depend on a thorough evaluation of local conditions and the potential added value. Further refinement of soil translocation techniques is needed to increase success rates.Combined effects of warming and drought on plant biomass depend on plant woodiness and community type
https://doi.org/10.1098/rspb.2022.1178Global warming and precipitation extremes (drought or increased precipitation) strongly affect plant primary production and thereby terrestrial ecosystem functioning. Recent syntheses show that combined effects of warming and precipitation extremes on plant biomass are generally additive, while individual experiments often show interactive effects, indicating that combined effects are more negative or positive than expected based on the effects of single factors. Here, we examined whether variation in biomass responses to single and combined effects of warming and precipitation extremes can be explained by plant growth form and community type. We performed a meta-analysis of 37 studies, which experimentally crossed warming and precipitation treatments, to test whether biomass responses to combined effects of warming and precipitation extremes depended on plant woodiness and community type (monocultures versus mixtures). Our results confirmed that the effects of warming and precipitation extremes were overall additive. However, combined effects of warming and drought on above- and belowground biomass were less negative in woody- than in herbaceous plant systems and more negative in plant mixtures than in monocultures. We further show that drought effects on plant biomass were more negative in greenhouse- than in field studies, suggesting that greenhouse experiments may overstate drought effects in the field. Our results highlight the importance of plant system characteristics to better understand plant responses to climate change.
Nutrient availability controls the impact of mammalian herbivores on soil carbon and nitrogen pools in grasslands
Grasslands are subject to considerable alteration due to human activities globally, including widespread changes in populations and composition of large mammalian herbivores and elevated supply of nutrients. Grassland soils remain important reservoirs of carbon (C) and nitrogen (N). Herbivores may affect both C and N pools and these changes likely interact with increases in soil nutrient availability. Given the scale of grassland soil fluxes, such changes can have striking consequences for atmospheric C concentrations and the climate. Here, we use the Nutrient Network experiment to examine the responses of soil C and N pools to mammalian herbivore exclusion across 22 grasslands, under ambient and elevated nutrient availabilities (fertilized with NPK + micronutrients). We show that the impact of herbivore exclusion on soil C and N pools depends on fertilization. Under ambient nutrient conditions, we observed no effect of herbivore exclusion, but under elevated nutrient supply, pools are smaller upon herbivore exclusion. The highest mean soil C and N pools were found in grazed and fertilized plots. The decrease in soil C and N upon herbivore exclusion in combination with fertilization correlated with a decrease in aboveground plant biomass and microbial activity, indicating a reduced storage of organic matter and microbial residues as soil C and N. The response of soil C and N pools to herbivore exclusion was contingent on temperature – herbivores likely cause losses of C and N in colder sites and increases in warmer sites. Additionally, grasslands that contain mammalian herbivores have the potential to sequester more N under increased temperature variability and nutrient enrichment than ungrazed grasslands. Our study highlights the importance of conserving mammalian herbivore populations in grasslands worldwide. We need to incorporate local‐scale herbivory, and its interaction with nutrient enrichment and climate, within global‐scale models to better predict land–atmosphere interactions under future climate change.https://doi.org/10.1111/gcb.15023Topsoil translocation in extensively managed arable field margins promotes plant species richness and threatened arable plant species
Since the 1950s, agriculture has intensified drastically, which has led to a significant biodiversity decline on arable lands. This decline was especially dramatic for segetal plant species, the specialist species of cereal fields. Due to the low population density and poor dispersal abilities of many segetal species, the recovery of species-rich fields may fail even though the environmental conditions are suitable. Therefore, conservation efforts including active restoration measures aimed at recovering segetal vegetation are needed. To this purpose, we propose to alleviate dispersal limitation by means of topsoil translocation from a species-rich donor arable field. At two receiver sites, we tested this technique using two topsoil-spreading densities, i.e. 2.5Lsoil/m2 and 5Lsoil/m2 in experimental plots (3 m2). At one receiver site, we tested the impact of topsoil translocation from two different donor sites, while in the other receiver site one donor site was used. We compared plant species diversity and composition of treated plots with control plots as well as with the species composition of the donor sites (field survey) and their seed bank (greenhouse survey). Species richness was increased by topsoil spreading, including richness of threatened species. 33% and 71% of the threatened species were successfully translocated respectively at the two receiver sites. At one site, plant cover was also increased, including threatened species cover. Conversely, topsoil spreading did not promote pernicious species that could affect farmer acceptance negatively. Vegetation of translocated plots was more similar in terms of species composition to donor site seed banks than to donor site field survey. The higher spreading density led to increased species richness when seed bank in topsoil had lower density. Our results show that topsoil translocation can be a highly effective method for restoring threatened segetal plant communities in agricultural landscapes. Even when a full plant community was already present (Receiver 1) topsoil transfer led to a doubling in species richness. The seed bank surveys were a good indicator of plant community composition upon topsoil translocation in the field and are therefore advisable to implement in the project-planning phase to evaluate donor site potential. From our results, we recommend to spread soil at an overall rate of 500 seeds/m2 equivalent. Future studies need to assess the long-term fate of the translocated species as well as the impacts of soil harvests on the donor sites to establish sustainable use levels.https://doi.org/10.1016/j.jenvman.2020.110126Single introductions of soil biota and plants generate long-term legacies in soil and plant community assembly
Recent demonstrations of the role of plant–soil biota interactions have challenged the conventional view that vegetation changes are mainly driven by changing abiotic conditions. However, while this concept has been validated under natural conditions, our understanding of the long‐term consequences of plant–soil interactions for above‐belowground community assembly is restricted to mathematical and conceptual model projections. Here, we demonstrate experimentally that one‐time additions of soil biota and plant seeds alter soil‐borne nematode and plant community composition in semi‐natural grassland for 20 years. Over time, aboveground and belowground community composition became increasingly correlated, suggesting an increasing connectedness of soil biota and plants. We conclude that the initial composition of not only plant communities, but also soil communities has a long‐lasting impact on the trajectory of community assembly.https://doi.org/10.1111/ele.13271Sensitivity of global soil carbon stocks to combined nutrient enrichment.
Soil stores approximately twice as much carbon as the atmosphere and fluctuations in the size of the soil carbon pool directly influence climate conditions. We used the Nutrient Network global change experiment to examine how anthropogenic nutrient enrichment might influence grassland soil carbon storage at a global scale. In isolation, enrichment of nitrogen and phosphorous had minimal impacts on soil carbon storage. However, when these nutrients were added in combination with potassium and micronutrients, soil carbon stocks changed considerably, with an average increase of 0.04 KgCm−2 year−1 (standard deviation 0.18 KgCm−2 year−1). These effects did not correlate with changes in primary productivity, suggesting that soil carbon decomposition may have been restricted. Although nutrient enrichment caused soil carbon gains most dry, sandy regions, considerable absolute losses of soil carbon may occur in high‐latitude regions that store the majority of the world's soil carbon. These mechanistic insights into the sensitivity of grassland carbon stocks to nutrient enrichment can facilitate biochemical modelling efforts to project carbon cycling under future climate scenarios.https://doi.org/10.1111/ele.13258Applying the aboveground-belowground interaction concept in agriculture
https://doi.org/10.3389/fevo.2019.00300Interactions between aboveground and belowground organisms are important drivers of plant growth and performance in natural ecosystems. Making practical use of such above-belowground biotic interactions offers important opportunities for enhancing the sustainability of agriculture, as it could favor crop growth, nutrient supply, and defense against biotic and abiotic stresses. However, the operation of above-and belowground organisms at different spatial and temporal scales provides important challenges for application in agriculture. Aboveground organisms, such as herbivores and pollinators, operate at spatial scales that exceed individual fields and are highly variable in abundance within growing seasons. In contrast, pathogenic, symbiotic, and decomposer soil biota operate at more localized spatial scales from individual plants to patches of square meters, however, they generate legacy effects on plant performance that may last from single to multiple years. The challenge is to promote pollinators and suppress pests at the landscape and field scale, while creating positive legacy effects of local plant-soil interactions for next generations of plants. Here, we explore the possibilities to improve utilization of above-belowground interactions in agro-ecosystems by considering spatio-temporal scales at which aboveground and belowground organisms operate. We identified that successful integration of above-belowground biotic interactions initially requires developing crop rotations and intercropping systems that create positive local soil legacy effects for neighboring as well subsequent crops. These configurations may then be used as building blocks to design landscapes that accommodate beneficial aboveground communities with respect to their required resources. For successful adoption of above-belowground interactions in agriculture there is a need for context-specific solutions, as well as sound socio-economic embedding.
Temporal carry-over effects in sequential plant-soil feedbacks
Plant–soil feedbacks (PSF) strongly influence plant performance. However, to what extent these PSF effects are persistent in the soil and how they are altered by species that subsequently condition the soil is unclear. Here we test how conspecific and heterospecific soil-conditioning effects interact across different soil-conditioning phases. We conducted a fully factorial glasshouse experiment where six plant species conditioned soils in two consecutive phases and measured the performance of Jacobaea vulgaris. The species that conditioned the soil during the second conditioning phase strongly determined the performance of J. vulgaris, but also the order and combination of species that conditioned the soil in the two phases accounted for a large part of the variance. For shoot biomass this interaction was the dominant variance component. We show that soil conditioning legacies carry-over and interact with the conditioning effects of succeeding plants. In the field, species replacements at the patch level often appear to be unpredictable and we suggest that sequential feedbacks may explain these apparently unpredictable transitions.https://doi.org/10.1111/oik.04526Two decades of altered snow cover does not affect soil microbial ability to catabolize carbon compounds in an oceanic alpine heath
Snow strongly affects ecosystem functioning in alpine environments with potential carry-over effects outside of snow periods. However, it is unclear whether changes in snow cover affect microbial community functioning in summer. In a field experiment, we tested whether manipulation of snow cover affected the functional capabilities of the microbial community either directly, or indirectly through concomitant changes in the vegetation. While 23 years of differential snow depth and persistence fundamentally changed the vegetation composition, the microbial community's ability to catabolize a range of carbon compounds was not altered. Instead, soil moisture content was the key driver of carbon catabolism by the microbial community.https://doi.org/10.1016/j.soilbio.2018.05.034Potential for synergy in soil inoculation for nature restoration by mixing inocula from different successional stages.
Background and aimshttps://doi.org//10.1007/s11104-018-3825-0
Soil inoculation is a powerful tool for the restoration of terrestrial ecosystems. However, the origin of the donor material may differentially influence early- and late-successional plant species. Donor soil from late-succession stages may benefit target plant species due to a higher abundance of soil-borne mutualists. Arable soils, on the other hand, may suppress ruderals as they support more root herbivores that preferentially attack ruderal plant species, while mid-succession soils may be intermediate in their effects on ruderals and target species performance. We hypothesized that a mixture of arable and late-succession inocula may outperform pure late-successional inocula for restoration, by promoting late-successional target plants, while simultaneously reducing ruderal species’ performance.
Methods
We conducted a glasshouse experiment and tested the growth of ruderal and target plant species on pure and mixed inocula. The inocula were derived from arable fields, mid-succession grasslands and late-succession heathlands and we created a replacement series testing different pairwise mixitures for each of these inocula types (ratios: 100:0, 75:25, 50:50, 25:75, 0:100 of inoculum A and B respectively).
Results
In general, we found that a higher proportion of heathland material led to a higher aboveground biomass of target plant species, while responses of ruderal species were variable. We found synergistic effects when specific inocula were mixed. In particular, a 50:50 mixture of heathland and arable soil in the inoculum led to a significant reduction in ruderal species biomass relative to the two respective pure inocula. The overall response was driven by Myosotis arvensis, since the other two ruderal species were not significantly affected.
Conclusions
Mixing inocula from different successional stages can lead to synergistic effects on restoration, but this highly depends on the specific combination of inocula, the mixing ratio and plant species. This suggest that specific inocula may need to be developed in order to rapidly restore different plant communities.Plant community evenness responds to spatial plant-soil feedback heterogeneity primarily through the diversity of soil conditioning
1.Plant-soil feedback (PSF) has been identified as a key driver of local plant diversity and evenness in competitive communities. However, while it has been shown that spatial PSF heterogeneity can alter plant performance and competitive interactions, there is no proof of principle that spatial PSF heterogeneity enhances community diversity.https://doi.org/10.1111/1365-2435.13017
2.Using a grassland model system we separated two aspects of spatial heterogeneity: the number of species conditioning the soil and spatial distribution of the PSFs.
3.Our data show that PSFs promoted a higher plant evenness when the soil was conditioned by multiple species (mixed-conditioned), then when the soil was conditioned by a single species (mono-conditioned). On mono-conditioned soils, heterospecifics typically outperformed the focal species. In addition, there was a trend for increasing community evenness from uniform, via fine-grained to coarse-grained mixed-conditioned soils, but this was not significant.
4.On mixed-conditioned soils, performance of all competing species was intermediate to the best and the worst mono-conditioned soils, leading to higher community evenness.
5.Our data demonstrate that PSFs play a role in promoting plant evenness. Across mono-conditioned soils, PSF led to altered competitive hierarchies. However, on soils conditioned by multiple species, competitive ability among species was more similar and this led to higher plant evenness. The spatial distribution of the heterogeneity, on the other hand, did not significantly affect plant evenness. Our data therefore show that community evenness was more strongly related to the number of plant species that conditioned the soil than the spatial distribution of the PSF heterogeneity. Future studies need to investigate the importance of PSFs in the field across plant life-stages and multiple generations.The prey’s scent – volatile organic compound mediated interactions between soil bacteria and their protist predators
Protists are major predators of bacteria in soils. However, it remains unknown how protists sense their prey in this highly complex environment. Here, we investigated whether volatile organic compounds (VOCs) of six phylogenetic distinct soil bacteria affect the performance of three different soil protists and how that relates to direct feeding interactions. We observed that most bacteria affected protist activity by VOCs. However, the response of protists to the VOCs was strongly dependent on both the bacterial and protist interacting partner. Stimulation of protist activity by volatiles and in direct trophic interaction assays often coincided, suggesting that VOCs serve as signals for protists to sense suitable prey. Furthermore, bacterial terpene synthase mutants lost the ability to affect protists, indicating that terpenes represent key components of VOC-mediated communication. Overall, we demonstrate that volatiles are directly involved in protist−bacterial predator−prey interactions.https://doi.org/10.1038/ismej.2016.144Going against the flow: a case for upstream dispersal and detection of uncommon dispersal events
* Dispersal and colonisation are key processes determining species survival, and their importance is increasing as a consequence of ongoing habitat fragmentation, land-use change and climate change. Identification of long-distance dispersal events, including upstream dispersal, and of the dispersal mechanisms and resulting spatial dispersal patterns involved provides much-needed information for conservation in an era of rapid environmental change. * However, quantifying contemporary dispersal among populations is far from straightforward. We used the relatively well-defined, typically linear, spatial structure of streams, rivers and their associated riparian and aquatic plant populations to illustrate this. We performed a literature review on studies where dispersal and its directionality (upstream versus downstream) were explicitly quantified. * Upstream dispersal was detected in the majority (75%) of examined stream and riparian plant species and mediated mainly by waterfowl, but also by other animals and wind. However, upstream movements are generally less frequent than downstream. Upstream dispersal can occur in excess of tens and sometimes even hundreds of kilometres. * Most of the reviewed studies suffer from important methodological limitations that generate difficulties in detecting uncommon dispersal events. Major limitations include use of molecular ecological analyses based on unrealistic assumptions, and the inability to separate seed from pollen flow. On the basis of these findings, we outline a flexible research design using DNA-based assignment methods that allows quantification of contemporary dispersal in future studies. We suggest four key improvements: (i) assignment of propagules and/or seedlings; (ii) use of spatial models to inform sampling design; (iii) reducing the influence of unsampled populations and (iv) combined use of nuclear and uniparentally inherited DNA markers to separate gene flow (including pollen and sperm) in general from propagule-mediated dispersal. In combination with direct measurements of seed dispersal these facilitate empirical quantification of dispersal and the detection of uncommon dispersal events, allowing more realistic assessment of spatial population dynamics, relevant for sedentary and relatively immobile organisms.https://doi.org/10.1111/fwb.12736Soil inoculation steers restoration of terrestrial ecosystems
Many natural ecosystems have been degraded because of human activities1,2 and need to be restored so that biodiversity is protected. However, restoration can take decades and restoration activities are often unsuccessful3 because of abiotic constraints (for example, eutrophication, acidification) and unfavourable biotic conditions (for example, competition or adverse soil community composition). A key question is what manageable factors prevent transition from degraded to restored ecosystems and what interventions are required for successful restoration2,4. Experiments have shown that the soil community is an important driver of plant community development5,6,7,8, suggesting that manipulation of the soil community is key to successful restoration of terrestrial ecosystems3,9. Here we examine a large-scale, six-year-old field experiment on ex-arable land and show that application of soil inocula not only promotes ecosystem restoration, but that different origins of soil inocula can steer the plant community development towards different target communities, varying from grassland to heathland vegetation. The impact of soil inoculation on plant and soil community composition was most pronounced when the topsoil layer was removed, whereas effects were less strong, but still significant, when the soil inocula were introduced into intact topsoil. Therefore, soil inoculation is a powerful tool to both restore disturbed terrestrial ecosystems and steer plant community development.https://doi.org/10.1038/nplants.2016.107Effects of spatial plant-soil feedback heterogeneity on plant performance in monocultures
1. Plant-soil feedback (PSF) effects have almost exclusively been quantified on homogeneous soils, but as different plant species will influence their local soil differently in reality PSF effects will be spatially heterogeneous. Whether plant performance in soils with spatially heterogeneous PSF can be predicted from pot experiments with homogeneous soils is unclear. 2. In a greenhouse experiment we tested the response of monocultures of six grassland species (two grasses, two legumes, and two forbs) to three spatially explicit treatments (fine-grain heterogeneity, coarse-grain heterogeneity, and homogeneous). Sixteen patches of conditioned soil (~6x6 cm) were placed within each container. For homogeneous treatments all patches contained the same conditioned soil within a container. The fine-grained heterogeneous treatment contained four differently conditioned soils that were applied following a Latin square design, while for the coarse-grained heterogeneous treatment four contiguous square blocks of four cells each were created in each container. 3. In general species grew worse on soil conditioned by conspecifics. However, when the biomass production on all homogeneous soil treatments (own and foreign soils) was averaged and compared to the heterogeneous treatments, we found that biomass production was lower than expected in the heterogeneous soils. This effect of heterogeneity depended on both the conditioning and test species, but most heterogeneity effects were negative. The grain of the heterogeneity (coarse vs. fine: at the chosen spatial scale) did not affect plant performance. 4. We hypothesize that a more diverse soil community is present in spatially heterogeneous soils. This increases i) the chance of plants to encounter its antagonists, which may then rapidly increase in numbers; and ii) the scope for synergistic co-infections. Together this may lead to non-additive responses of plants to spatial heterogeneity in PSF. 5. Synthesis. Plant performance was lower in spatially heterogeneous soils than predicted by spatially homogeneous soils. In natural grasslands that have mixed plant communities conditioning the soil plant-soil feedback (PSF) effects on plant performance may therefore be more negative than what is predicted from pot experiments. Our results emphasise the need to incorporate the spatial dynamics of PSF both in empirical and modelling studies if we are to understand the role of PSF in plant-plant interactions and plant community dynamics. This article is protected by copyright. All rights reserved.https://doi.org/10.1111/1365-2745.12521Snow cover, freeze-thaw, and the retention of nutrients in an oceanic mountain ecosystem
As the climate warms, winters with less snow and therefore more soil freeze-thaw cycles are likely to become more frequent in oceanic mountain areas. It is a concern that this might impair the soil's ability to store carbon and nutrients, and lead to increased leaching losses of dissolved C and nutrients and subsequent changes in nutrient cycling and ecosystem productivity. Through a combination of laboratory and field experiments, we studied short-term effects of changing winter conditions on carbon and nutrient leaching from two plant-soil systems with contrasting snow conditions (shallow/intermittent vs. deep/persistent snow). In the laboratory we exposed cores (soil and vegetation) from sites with either intermittent or persistent winter snow cover to five different freeze-thaw scenarios of realistic frequency and duration. Additionally, we set up a transplant experiment at our field site by reciprocally transplanting soil-plant monoliths between sites with intermittent and persistent snow. Together, the field and laboratory experiments aimed to assess how carbon and nutrient leaching was affected by both historical snow conditions and short-term (through freeze-thaw scenarios and transplantation) changes in snow cover and thermal conditions. Both a greater number of freeze-thaw cycles and longer duration of sub-zero temperatures increased carbon and nutrient leaching from incubated soil cores. Cores from sites with persistent snow generally had lower nutrient losses under control conditions, but greater losses following induced freeze-thaw cycles than cores from intermittent snow sites. The character of the leached dissolved organic carbon (DOC) suggested fresh organic material, such as live plant roots or microbes, as the source of carbon and nutrients. Nutrient losses from the plant-soil systems in the field were greater at sites with persistent winter snow due to greater volumes of percolating water in spring. This suggests that increasingly severe and frequent soil freeze-thaw events in oceanic mountain ecosystems can enhance the mobilization of C, N and P in labile forms but, in the absence of water fluxes, these nutrients would remain available for in-situ cycling. Thus, under future warmer winter conditions, increased carbon and nutrient losses from oceanic mountain ecosystems could occur if winters with little snow coincide with wet spring conditions.https://doi.org/10.1890/ES15-00099.1Microclimatological consequences for plant and microbial composition in Sphagnum-dominated peatlands
In three Scandinavian peatlands we studied to what extent plant and microbial community compositions are governed by local-scale microhabitat, with a special interest in the effect of aspect (i.e. exposition of slopes). Despite differences in solar irradiance between the south- and north-facing slopes, maximum temperature was elevated in the south-facing slopes at the most northern site only. Pore-water nutrient concentrations were not affected by aspect, yet dissolved organic carbon concentrations were higher in the south-facing microhabitats. This was likely caused by higher vascular plant biomass. Plant and microbial community composition clearly differed among sites. In all three sites, microhabitat (i.e. prevailing water-table depth) affected the plant and microbial community compositions. Aspect, however, did not affect community composition, even though microclimate significantly differed between the south- and the north-facing aspects at the northernmost site. Our results highlight the complex link between plant community composition, microbial community and environmental conditions, which deserves much more attention than currently in order to fully understand the effects of climate change on peatland ecosystem function.II
Popular-scientific publications
Afgraven, bodemtransplantaties en uitstrooien van maaisel op voormalige landbouwgronden: het Reijerscamp experiment
Op de Reijerscamp bij Wolfheze zijn de effectiviteit van bodemtransplantaties en het uitstrooien van maaisel voor het ontwikkelen van heide en heischraal grasland op een voormalig landbouwgebied vergeleken. Deze natuurherstelmaatregelen zijn toegepast en getest in gebieden waar de toplaag van de bodem (de voormalige bouwvoor) is afgegraven en in niet-afgegraven gebieden. Wat zijn de resultaten van dit experiment en welke meerwaarde levert bodemtransplantatie voor natuurontwikkeling op?
Projects & collaborations
Projects
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Bodemleven onder toekomstbestendige bossen
Stikstofdepositie en klimaatverandering leiden tot bodemverzuring en verdroging. Hierdoor neemt de vitaliteit van bossen sterk af. In dit project wordt geprobeerd de bossen in Het Nationale Park De Hoge Veluwe te revitaliseren.
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Soil multifunctionality: from biodiversity associations to understanding mechanisms (MultiSol)
My MSCA-project will elucidate the mechanisms underlying trade-offs and synergies among soil functions and reveal how differences among soils drive differences in soil multifunctionality.
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Onder het maaiveld
Onder het Maaiveld is een driejarig programma van IUCN NL, De Vlinderstichting, NIOO-KNAW, WUR en het Centrum voor Bodemecologie. Samen met andere organisaties werken wij aan een structurele verandering in de omgang met onze waardevolle bodem. Ons doel? Herstel van het bodemleven in Nederland, als basis voor een gezonde natuur en een gezonde maatschappij.
Additional Projects
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African roads to Sustainable Agroecology Summer School – hot topics and targeted solutions (AfriSASS)
2021–2022In this project (with NIOO, ETH Zurich, CIRAD, PE&RC, University of Eldoret), we developped a new transdisciplinary field course on agro-ecology in the Elegyo-Marakwet area, Kenya: "African roads to Sustainable Agroecology". A new edition of the course is anticipated in 2024.
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NWO Rubicon Fellowship: Soil microbiome engineering to reverse land degradation and enhance crop production in sub-Saharan Africa
2018–2021Many soils in sub-Saharan Africa (SSA) have been chemically, physically and biologically degraded. As a result an estimated 50% of agricultural soils do not increase productivity in response to mineral fertiliser addition, so called non-responsive soils. These soils can be restored using Integrated Soil Fertility Management (ISFM), but this requires substantial amounts of organic substrates (e.g. manure) to be added to the soil for many years. Many farmers in SSA do not possess these kinds of resources. Plants, including crops, grow in tight associations with their specific soil microbiomes – the collective diversity of bacteria, archaea, fungi, protists, and other microorganisms found in soil. The soil microbiome can enhance plant functioning, particularly when introduced as consortia of species.
In this project we combine modern high-throughput DNA sequencing methods and controlled greenhouse cultivations to explore the relationship between Kenyan maize crops and the natural diversity of soil microbiomes. We assess microbiome diversity in central Kenya, screen the potential of naturally occurring soil microbiomes to improve the performance of maize crops, and use host-mediated selection to engineer microbiomes competent to function under reduced organic substrate inputs.
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Soil heterogeneity as a key to restoring nature and biodiversity on former arable fields
2012–2017NWO, Biodiversiteit werkt, with Prof. T.M. Bezemer and Prof. W.H. van der Putten.
Outreach
Jasper actively takes his research out of academia and to practitioners, policy makers and the general public. For this work he received the 2016 Parnassia Award from the Radboud University Nijmegen.
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Enhancing Soil Biodiversity
At NIOO, we are on a mission to explore the strange world beneath our feet, to seek out new soil-borne life, uncover new miniature civilisations, and to boldly take humankind where it could not go before.
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Forest soil boost for iconic Dutch national park
A major NIOO-supervised experiment is underway in one of the Netherlands most iconic nature areas, with a key role for the soil.
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Global comparison shows: soil transplantation boosts nature restoration
A new study comparing 46 field experiments in 17 countries across four continents shows that areas in need of nature restoration benefit from soil transplantation. The results were collected by an international team led by Jasper Wubs (NIOO-KNAW).
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Spotlight on living soil at COP15 biodiversity conference
The UN Biodiversity Conference in Montreal (COP15) is discussing global action to reverse biodiversity loss. Healthy, living soil is of key importance.
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Restoring nature the fast way
Restoring nature is not for the impatient: it takes a lot of time before the right plant species establish themselves. But experiments show there's a way to speed up the process, from decades to just a few years. A new website from the Netherlands Institute of Ecology (NIOO-KNAW) tells you everything you need to know. Meanwhile, one of the researchers working on this pioneering approach defended his PhD thesis this week.
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Soil inoculation works!
Restoring nature, for instance on former farmland? That works a lot faster, more precise, and less disruptive via soil inoculation. Take a bit of healthy soil from a natural area close by and restore the desired type of nature within a couple of years. In the journal Nature Plants, the Netherlands Institute of Ecology (NIOO-KNAW) and Natuurmonumenten (Society for Nature Conservation) also solve a long-lasting subject of discussion: it’s the soil bugs that steer such nature restoration.
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