Elly Morriën

Dr. Elly Morriën

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Visiting Address

Droevendaalsesteeg 10
6708 PB Wageningen

+31 (0) 317 47 34 00

The Netherlands



I am a soil ecologist working with soil scientists. This puts me in a bridging position between disciplines in which I want to fill the knowledge gap on the contribution of soil biota in stabilizing organic matter in soil.


Trained as an ecologist I performed my PhD at the NIOO-KNAW but graduated at the Nematology department at the Wageningen University on range-expanding plant species and their belowground interactions with microbes and nematodes. After my graduation I did a postdoc at NIOO-KNAW on grassland restoration and how this changed biogeochemical cycling, soil biodiversity and soil networks in a European project EcoFINDERS. Here I combined field measurements with greenhouse experiments using stable isotope probing to trace the flow of carbon and nitrogen through the members of the soil food web. The ideas sprouted from this postdoc let to a NWO-veni grant which I performed at the University of Amsterdam. Experimentally, the collaboration with NIOO was heavy during this research-fellowship as my experiments were centered around carbon tracing through the soil food web with gut content analyses, root exudates steering soil microbial composition and functioning and soil transplantation experiments for which NIOO-KNAW has excellent facilities. Since 2019 I am a tenure tracker at the University of Amsterdam, but because of my close affinity with the topical research at NIOO-KNAW, I remained a guest researcher at this institute.



  • 2019–Present
    Tenure Tracker University of Amsterdam
  • 2015–2019
    Research-fellow/Veni laureate University of Amsterdam
  • 2011–2015
    postdoc NIOO-KNAW


  • 2005–2011
    PhD student NIOO-KNAW/Wageningen University
  • 1999–2005
    BSc & MSc in Ecology at Vrije Universiteit Amsterdam

Editorial board memberships

Functional Ecology


Peer-reviewed publications

  • Applied Soil Ecology

    Short-term N addition in a Pinus tabuliformis plantation

    Jiaoyang Zhang, Zemin Ai, Hongfei Liu, D. W.S. Tang, Xiaomei Yang, Guoliang Wang, Ying Liu, Guobin Liu, Elly Morrien, Sha Xue

    Increasing nitrogen (N) deposition severely impacts terrestrial biogeochemical cycles by altering the stoichiometry of ecological components. Although microbes are known to play an important role in biogeochemical cycles, the mechanisms how soil microbes drive nutrient cycling remain elusive under N deposition. Therefore, we investigated changes in microbial community diversity, composition, and interactions, and elucidated the relationship among microbial community responses, soil available nutrients, and ecological stoichiometry resulting from two years of N addition to a Pinus tabuliformis plantation on the Loess Plateau at four rates of N addition (0 (N0), 3.0 (N3), 6.0 (N6), and 9.0 (N9) g N m−2 y−1). N addition significantly influenced microbial composition, decreasing the relative abundance of Acidobacteria and Basidiomycota along N addition gradients and increasing the relative abundance of Ascomycota from N3 to N9. Along N addition gradients except N3, bacterial interactions increased from 62.70% to 73.38%, whereas interactions between bacterial and fungal communities decreased from 34.44% to 24.43%. Among all microbial interactions, the positive ones accounted for a larger proportion (over 55%), indicating a predominance of mutualism under all N addition treatments. Changes in the microbial composition were correlated with soil resource stoichiometry factors, including soil organic carbon: soil total N (SOC:TN) and SOC: soil total phosphorus (SOC:TP), whereas the topological network features were correlated with ammonium N (NH4+-N), nitrate N (NO3-N), β-1,4-N-acetylglucosaminidase (NAG), alkaline phosphatase (AP), and eco-enzymatic stoichiometry. Therefore, the soil variables that caused changes to microbial composition and interactions were different. In this sense, microbial community compositions were more easily affected by soil resource stoichiometry, whereas microbial interactions were more easily affected by soil available nutrients. In addition, changes to microbial interactions could mediate microbial metabolism via eco-enzyme expression.

  • Geoderma

    Will fungi solve the carbon dilemma?

    Emilia Hannula, Elly Morrien

    Soils are hotspots of diversity and sustain many globally important functions. Here we focus on the most burning issue: how to keep soils as carbon sinks while maintaining their productivity. Evidence shows that life in soils plays a crucial role in improving soil health yet soil ecological processes are often ignored in soil sciences. In this review, we highlight the potential of fungi to increase soil carbon sequestration while maintaining crop yield, functions needed to sustain human population on Earth and at same time keep the Earth livable. We propose management strategies that steer towards more fungal activity but also high functional diversity of fungi which will lead to more stable carbon sources in soil but also affects the structure of the soil food web up to ecosystem level. We list knowledge gaps that limit our ability to steer soil fungal communities such that stabilising carbon in top soils becomes more effective. Using the natural capacity of a biodiverse soil community to sequester carbon delivers double benefit: reduction of atmospheric carbon dioxide by storing photosynthesized carbon in soil and increasing agricultural yields by restoring organic matter content of degraded soils.

  • Biology and Fertility of Soils

    Greenhouse gas (CO2, CH4, and N2O) emissions after abandonment of agriculture, and insights on the response of the (de)nitrifier

    Alaa H.M. El-Hawwary, Kristof Brenzinger, Hyo Jung Lee, Annelies Veraart, Elly Morrien, Michael Schloter, Wim H. van der Putten, Paul Bodelier, Adrian Ho
    The GHG (CO2, CH4, N2O) emission potential along a chronosequence of former agricultural soils abandoned for 9 to 32 years were compared to an actively managed (on-going) agricultural soil (reference). The soils were incubated in mesocosms with and without manure amendment, and microbial functional groups involved in nitrous oxide emission were quantitatively assessed. Carbon dioxide emission significantly increased after agriculture abandonment (< 24 years) consistent with higher decomposition rate, but total emission decreased in the long term (> 29 years). With the cessation of agriculture, the abandoned sites generally became a net methane sink. Notably, total nitrous oxide emission showed a significant monotonic decrease over years of abandonment in response to manure amendment, possibly reflecting an altered capacity for (de)nitrification as indicated in the response of the (de)nitrifier abundance. Overall, our findings suggest that the GHG legacy of agriculture diminishes over time (> 29 years), with lowered GHG emissions and global warming potential (GWP) after abandonment of agriculture.
  • One Earth

    Ecosystem coupling

    Raul Ochoa-Hueso, Manuel Delgado-Baquerizo, Anita C. Risch, Maarten Schrama, Elly Morrien, S. Henrik Barmentlo, Stefan Geisen, Emilia Hannula, Monika Carol Resch, Basten Snoek, Wim H. van der Putten

    Global change frequently disrupts the connections among species, as well as among species and their environment, before the most obvious impacts can be detected. Therefore, we need to develop a unified conceptual framework that allows us to predict early ecological impacts under changing environments. The concept of coupling, defined as the multiple ways in which the biotic and abiotic components of ecosystems are orderly connected across space and/or time, may provide such a framework. Here, we operationally define the coupling of ecosystems based on a combination of correlational matrices and a null modeling approach. Compared with null models, ecosystems can be (1) coupled; (2) decoupled; and (3) anticoupled. Given that more tightly coupled ecosystems displaying higher levels of internal order may be characterized by a more efficient capture, transfer, and storage of energy and matter (i.e., of functioning), understanding the links between coupling and functioning may help us to accelerate the transition to planetary-scale sustainability. This may be achieved by promoting self-organized order.

  • Ecosphere

    Resilience in coastal dune grasslands: pH and soil organic matter effects on P nutrition, plant strategies, and soil communities

    Annemieke Kooijman, Elly Morrien, Gerard Jagers op Akkerhuis, Anna Missong, Roland Bol, Erwin Klumpp, Rutger van Hall, Mark van Til, Karsten Kalbitz, Jaap Bloem
    Abstract Soil organic matter (SOM) and pH are key ecosystem drivers, influencing resilience to environmental change. We tested the separate effects of pH and SOM on nutrient availability, plant strategies, and soil community composition in calcareous and acidic Grey dunes (H2130) with low, intermediate, and/or high SOM, which differ in sensitivity to high atmospheric N deposition. Soil organic matter was mainly important for biomass parameters of plants, microbes, and soil animals, and for microarthropod diversity and network complexity. However, differences in pH led to fundamental differences in P availability and plant strategies, which overruled the normal soil community patterns, and influenced resilience to N deposition. In calcareous dunes with low grass-encroachment, P availability was low despite high amounts of inorganic P, due to low solubility of calcium phosphates and strong P sorption to Fe oxides at high pH. Calcareous dunes were dominated by low-competitive arbuscular mycorrhizal (AM) plants, which profit from mycorrhiza especially at low P. In acidic dunes with high grass-encroachment, P availability increased as calcium phosphates dissolved and P sorption weakened with the shift from Fe oxides to Fe-OM complexes. Weakly sorbed and colloidal P increased, and at least part of the sorbed P was organic. Acidic dunes were dominated by nonmycorrhizal (NM) plants, which increase P uptake through exudation of carboxylates and phosphatase enzymes, which release weakly sorbed P, and disintegrate labile organic P. The shifts in P availability and plant strategies also changed the soil community. Contrary to expectations, the bacterial pathway was more important in acidic than in calcareous dunes, possibly due to exudation of carboxylates and phosphatases by NM plants, which serve as bacterial food resource. Also, the fungal AM pathway was enhanced in calcareous dunes, and fungal feeders more abundant, due to the presence of AM fungi. The changes in soil communities in turn reduced expected differences in N cycling between calcareous and acidic dunes. Our results show that SOM and pH are important, but separate ecosystem drivers in Grey dunes. Differences in resilience to N deposition are mainly due to pH effects on P availability and plant strategies, which in turn overruled soil community patterns.
  • Nature Ecology and Evolution

    The long-term restoration of ecosystem complexity

    David Moreno Mateos, Antton Alberdi, Elly Morrien, Wim H. van der Putten, Asun Rodríguez-Uña, Daniel Montoya
    Multiple large-scale restoration strategies are emerging globally to counteract ecosystem degradation and biodiversity loss. However, restoration often remains insufficient to offset that loss. To address this challenge, we propose to focus restoration science on the long-term (centuries to millennia) re-assembly of degraded ecosystem complexity integrating interaction network and evolutionary potential approaches. This approach provides insights into eco-evolutionary feedbacks determining the structure, functioning and stability of recovering ecosystems. Eco-evolutionary feedbacks may help to understand changes in the adaptive potential after disturbance of metacommunity hub species with core structural and functional roles for their use in restoration. Those changes can be studied combining a restoration genomics approach based on whole-genome sequencing with replicated space-for-time substitutions linking changes in genetic variation to functions or traits relevant to the establishment of evolutionarily resilient communities. This approach may set the knowledge basis for future tools to accelerate the restoration of ecosystems able to adapt to ongoing global changes.
  • Fungal Ecology

    Rhizosphere fungi actively assimilating plant-derived carbon in a grassland soil

    Emilia Hannula, Elly Morrien, Wim H. van der Putten, Wietse de Boer
    Despite the advantages of the next generation sequencing (NGS) techniques, one of their caveats is that they do not differentiate between microbes that are actively participating in carbon cycling in the rhizosphere and microbes performing other functions in the soils. Here we combined DNA-SIP with NGS to investigate which rhizosphere fungi actively assimilate plant-derived carbon. We provided 13CO2 to plants in intact soil cores collected from a grassland and sampled the rhizosphere in a time series to follow the fate of carbon in the rhizosphere mycobiome. We detected a difference between active rhizosphere fungi using plant-derived carbon and the total mycobiota: 58% of fungal species were using fresh rhizodeposits, and an additional 22% of fungal species received carbon several weeks later while 20% were not involved in cycling of freshly photosynthesized carbon. We show that members of Ascomycota, Mucoromycota, and basidiomycete yeasts were first users of freshly photosynthesized carbon, while fungi not using recently fixed carbon consisted mainly of mycelial (non-yeast) Basidiomycota. We conclude that a majority of fungi inhabiting the rhizosphere in this grassland ecosystem are actively using plant derived carbon either directly or via food-web interactions.
  • Trends in Plant Science

    Network Analyses Can Advance Above-Belowground Ecology

    Kelly Ramirez, Stefan Geisen, Elly Morrien, Basten Snoek, Wim H. van der Putten
    An understanding of above-belowground (AG-BG) ecology is important for evaluating how plant interactions with enemies, symbionts, and decomposers affect species diversity and will respond to global changes. However, research questions and experiments often focus on only a limited number of interactions, creating an incomplete picture of how entire communities may be involved in AG-BG community ecology. Therefore, a pressing challenge is to formulate hypotheses of AG-BG interactions when considering communities in their full complexity. Here we discuss how network analyses can be a powerful tool to progress AG-BG research, link across scales from individual to community and ecosystem, visualize community interactions between the two (AG and BG) subsystems, and develop testable hypotheses.
  • Nature Communications

    Soil networks become more connected and take up more carbon as nature restoration progresses

    Elly Morrien, Emilia Hannula, Basten Snoek, Nico Helmsing, Hans Zweers, Mattias De Hollander, Raquel Lujan Soto, M.L. Bouffaud, M. Buée, Wim Dimmers, Henk Duyts, Stefan Geisen, M. Girlanda, R.I. Griffiths, H-B. Jørgensen, J. Jensen, Pierre Plassart, Dirk Redecker, R.M. Schmelz, O. Schmidt, B.C. Thomson, Emilie Tisserant, S. Uroz, A. Winding, M.J. Bailey, M. Bonkowski, Jack H. Faber, F. Martin, P. Lemanceau, Wietse de Boer, Hans van Veen, Wim H. van der Putten
    Soil organisms have an important role in aboveground community dynamics and ecosystem functioning in terrestrial ecosystems. However, most studies have considered soil biota as a black box or focussed on specific groups, whereas little is known about entire soil networks. Here we show that during the course of nature restoration on abandoned arable land a compositional shift in soil biota, preceded by tightening of the belowground networks, corresponds with enhanced efficiency of carbon uptake. In mid- and long-term abandoned field soil, carbon uptake by fungi increases without an increase in fungal biomass or shift in bacterial-to-fungal ratio. The implication of our findings is that during nature restoration the efficiency of nutrient cycling and carbon uptake can increase by a shift in fungal composition and/or fungal activity. Therefore, we propose that relationships between soil food web structure and carbon cycling in soils need to be reconsidered
  • ISME Journal

    Shifts in rhizosphere fungal community during secondary succession following abandonment from agriculture

    Emilia Hannula, Elly Morrien, Mattias De Hollander, Wim H. van der Putten, Hans van Veen, Wietse de Boer
    Activities of rhizosphere microbes are key to the functioning of terrestrial ecosystems. It is commonly believed that bacteria are the major consumers of root exudates and that the role of fungi in the rhizosphere is mostly limited to plant-associated taxa, such as mycorrhizal fungi, pathogens and endophytes, whereas less is known about the role of saprotrophs. In order to test the hypothesis that the role of saprotrophic fungi in rhizosphere processes increases with increased time after abandonment from agriculture, we determined the composition of fungi that are active in the rhizosphere along a chronosequence of ex-arable fields in the Netherlands. Intact soil cores were collected from nine fields that represent three stages of land abandonment and pulse labeled with 13CO2. The fungal contribution to metabolization of plant-derived carbon was evaluated using phospholipid analysis combined with stable isotope probing (SIP), whereas fungal diversity was analyzed using DNA-SIP combined with 454-sequencing. We show that in recently abandoned fields most of the root-derived 13C was taken up by bacteria but that in long-term abandoned fields most of the root-derived 13C was found in fungal biomass. Furthermore, the composition of the active functional fungal community changed from one composed of fast-growing and pathogenic fungal species to one consisting of beneficial and slower-growing fungal species, which may have essential consequences for the carbon flow through the soil food web and consequently nutrient cycling and plant succession.
  • Soil Biology & Biochemistry

    Understanding soil food web dynamics, how close do we get?

    Soil food webs are traditionally considered to have distinct energy channels through which resources flow belowground. Resources enter the soil food web either from roots or from detrital inputs. Compared to this traditional view we are now much more aware of the flow of carbon, nitrogen and other resources through the microbes in the soil food web. Currently, the function of some groups of bacteria and fungi is known. The lowering of the costs of high throughput sequencing methods enables us to acquire more data on who is around, when and where in the soil food web. For soil fauna, gut content analyses in combination with sequencing can reveal feeding preferences, which enables establishing real trophic links based on observations, which can then be visualised as networks of feeding interactions. The fate of carbon flow through the soil food web can be traced by using stable isotopes combined with sequence based techniques. This provides insight into trophic connections and interaction strength. As the sequencing costs decrease rapidly, the level of detail in soil food web knowledge will similarly increase rapidly and enhance the feasibility of combined techniques. Using these techniques to broaden our insight into soil subsystems and their soil food webs will lead to more targeted decisions on management practices.
  • Oecologia

    Herbivory and dominance shifts among exotic and congeneric native plant species during plant community establishment

    T. Engelkes, Annelein Meisner, Elly Morrien, Olga Kostenko, Wim H. van der Putten, Mirka Macel
    Invasive exotic plant species often have fewer natural enemies and suffer less damage from herbivores in their new range than genetically or functionally related species that are native to that area. Although we might expect that having fewer enemies would promote the invasiveness of the introduced exotic plant species due to reduced enemy exposure, few studies have actually analyzed the ecological consequences of this situation in the field. Here, we examined how exposure to aboveground herbivores influences shifts in dominance among exotic and phylogenetically related native plant species in a riparian ecosystem during early establishment of invaded communities. We planted ten plant communities each consisting of three individuals of each of six exotic plant species as well as six phylogenetically related natives. Exotic plant species were selected based on a rapid recent increase in regional abundance, the presence of a congeneric native species, and their co-occurrence in the riparian ecosystem. All plant communities were covered by tents with insect mesh. Five tents were open on the leeward side to allow herbivory. The other five tents were completely closed in order to exclude insects and vertebrates. Herbivory reduced aboveground biomass by half and influenced which of the plant species dominated the establishing communities. Exposure to herbivory did not reduce the total biomass of natives more than that of exotics, so aboveground herbivory did not selectively enhance exotics during this early stage of plant community development. Effects of herbivores on plant biomass depended on plant species or genus but not on plant status (i.e., exotic vs native). Thus, aboveground herbivory did not promote the dominance of exotic plant species during early establishment of the phylogenetically balanced plant communities.
  • Journal of Ecology

    Soil microbial community structure of range-expanding plant species differs from co-occurring natives

    Elly Morrien, Wim H. van der Putten
    1. Due to global warming and other changes in the environment, many native and exotic plant species show range expansion from lower to higher latitudes. In the new range, the (in)ability of range-expanding plants to establish associations with local soil microbes can have important consequences for plant abundance; however, very little information exists on rhizosphere communities of range-expanding plant species. Here, we examine the rhizosphere microbial community composition of range-expanding plant species in comparison with phylogenetically related species that are native in the invaded range. 2. We tested the hypothesis that range-expanding plants species would promote fewer shifts in rhizosphere communities than congeneric natives would. In order to test this, soil was collected from the invaded habitat and six range-expanding and nine congeneric natives were planted individually in pots to condition soil microbial communities. 3. After harvesting, individuals of the same species were planted in conditioned own and control soils to test the legacy effects of soil conditioning on biomass production. The control soils were mixtures of soils conditioned by all other plant species, except congenerics. After 10 weeks of plant growth, we determined the rhizosphere community composition of bacteria, fungi, arbuscular mycorrhizal fungi (AMF) and Fusarium spp. 4. All groups of microbes were analysed qualitatively using denaturating gradient gel electrophoresis (DGGE). Ergosterol was determined as a quantitative measure of nonarbuscular mycorrhizal fungal biomass, and real-time PCR was applied to detect amounts of Fusarium spp. 5. Range-expanding plants had less fungal hyphal biomass and lower amounts of Fusarium spp. in the rhizosphere than congenerics. Bacterial community composition was influenced by a combination of soil conditioning and plant origin, whereas fungal communities, AMF and Fusarium spp. were less pronounced in their responses to the experimental treatments. 6. Synthesis. We conclude that the lack of legacy effects in range-expanding plant species compared with natives may be due to differences in bacterial rhizosphere community composition, or to different quantities of potential pathogenic fungi. If the range-expanding plant species were benefiting more from AMF, effects will not have been due to differences in community composition, but we cannot exclude other options, such as different effectiveness of AMF or other soil biota in the rhizosphere of range-expanding vs. native plant species. The greater accumulation of bacterial and fungal pathogens in the rhizosphere of natives in relation to range expanders might explain the successful establishment of range-expanding plants.
  • Journal of Ecology

    Hierarchical responses of plant–soil interactions to climate change: consequences for the global carbon cycle

    Richard D. Bardgett, P. Manning, Elly Morrien, F.T. De Vries
    1.Interactions between plant and soil communities play a major role in determining the impact of climate change on ecosystem functioning and the carbon cycle, and the mechanisms involved operate over a wide range of spatial and temporal scales. 2.We present a framework for understanding the consequences of climate-induced changes in plant–soil feedback for the carbon cycle. The framework describes a hierarchy of mechanisms by which changes in climate impact on ecosystem carbon dynamics at three levels of response, namely individual and community reordering and species immigration and loss. 3.For each level, we identify the mechanisms by which climate change impacts on plant–soil interactions with consequences for the carbon cycle. We also demonstrate that the potential for decoupling of plant–soil interactions increases across the three levels of response, being greatest with species immigration and/or loss, for example, if plants were to undergo a biome shift, but their associated soil communities did not. Such decoupling is a largely unrecognized, but potentially important regulator of the future global carbon cycle. 4.Synthesis. The framework presented here highlights a need for a new approach to the study of climate change impacts on plant–soil interactions and carbon cycling that integrates this hierarchy of responses, and incorporates the decoupling of above-ground and below-ground networks, across a range of temporal and spatial scales, and ecosystems.
  • Oikos

    Effects of native and exotic range-expanding plant species on taxonomic and functional composition of nematodes in the soil food web

    Elly Morrien, Henk Duyts, Wim H. van der Putten
    Due to climate warming, many plant species shift ranges towards higher latitudes. Plants can disperse faster than most soil biota, however, little is known about how range-expanding plants in the new range will establish interactions with the resident soil food web. In this paper we examine how the soil nematode community from the new range responds to range-expanding plant species compared to related natives. We focused on nematodes, because they are important components in various trophic levels of the soil food web, some feeding on plant roots, others on microbes or on invertebrates. We expected that range expanding plant species have fewer root-feeding nematodes, as predicted by enemy release hypothesis. We therefore expected that range expanders affect the taxonomic and functional composition of the nematode community, but that these effects would diminish with increasing trophic position of nematodes in the soil food web. We exposed six range expanders (including three intercontinental exotics) and nine related native plant species to soil from the invaded range and show that range expanders on average had fewer root-feeding nematodes per unit root biomass than related natives. The range expanders showed resistance against rather than tolerance for root-feeding nematodes from the new range. On the other hand, the overall taxonomic and functional nematode community composition was influenced by plant species rather than by plant origin. The plant identity effects declined with trophic position of nematodes in the soil food web, as plant feeders were influenced more than other feeding guilds. We conclude that range-expanding plant species can have fewer root-feeding nematodes per unit root biomass than related natives, but that the taxonomic and functional nematode community composition is determined more by plant identity than by plant origin. Plant species identity effects decreased with trophic position of nematodes in the soil food web.
  • Ecology

    Additive effects of aboveground polyphagous herbivores and soil feedback in native and range-expanding exotic plants

    Elly Morrien, T. Engelkes, Wim H. van der Putten
    Plant biomass and plant abundance can be controlled by aboveground and belowground natural enemies. However, little is known about how the aboveground and belowground enemy effects may add up. We exposed 15 plant species to aboveground polyphagous insect herbivores and feedback effects from the soil community alone, as well as in combination. We envisaged three possibilities: additive, synergistic, or antagonistic effects of the aboveground and belowground enemies on plant biomass. In our analysis, we included native and phylogenetically related range-expanding exotic plant species, because exotic plants on average are less sensitive to aboveground herbivores and soil feedback than related natives. Thus, we examined if lower sensitivity of exotic plant species to enemies also alters aboveground-belowground interactions. In a greenhouse experiment, we exposed six exotic and nine native plant species to feedback from their own soil communities, aboveground herbivory by polyphagous insects, or a combination of soil feedback and aboveground insects and compared shoot and root biomass to control plants without aboveground and belowground enemies. We observed that for both native and range-expanding exotic plant species effects of insect herbivory aboveground and soil feedback added up linearly, instead of enforcing or counteracting each other. However, there was no correlation between the strength of aboveground herbivory and soil feedback. We conclude that effects of polyphagous aboveground herbivorous insects and soil feedback add up both in the case of native and related range-expanding exotic plant species, but that aboveground herbivory effects may not necessarily predict the strengths of soil feedback effects.
  • Annals of Botany

    Climate change and invasion by intracontinental range-expanding exotic plants: the role of biotic interactions

    Elly Morrien, T. Engelkes, Mirka Macel, Annelein Meisner, Wim H. van der Putten
    Background and Aims: In this Botanical Briefing we describe how the interactions between plants and their biotic environment can change during range-expansion within a continent and how this may influence plant invasiveness. Scope: We address how mechanisms explaining intercontinental plant invasions by exotics (such as release from enemies) may also apply to climate-warming-induced range-expanding exotics within the same continent. We focus on above-ground and below-ground interactions of plants, enemies and symbionts, on plant defences, and on nutrient cycling. Conclusions: Range-expansion by plants may result in above-ground and below-ground enemy release. This enemy release can be due to the higher dispersal capacity of plants than of natural enemies. Moreover, lower-latitudinal plants can have higher defence levels than plants from temperate regions, making them better defended against herbivory. In a world that contains fewer enemies, exotic plants will experience less selection pressure to maintain high levels of defensive secondary metabolites. Range-expanders potentially affect ecosystem processes, such as nutrient cycling. These features are quite comparable with what is known of intercontinental invasive exotic plants. However, intracontinental range-expanding plants will have ongoing gene-flow between the newly established populations and the populations in the native range. This is a major difference from intercontinental invasive exotic plants, which become more severely disconnected from their source populations.
  • Biological Invasions

    Ecological fits, mis-fits and lotteries involving insect herbivores on the invasive plant, Bunias orientalis

    Jeff A. Harvey, Arjen Biere, Taiadjana Fortuna, Louise E.M. Vet, T. Engelkes, Elly Morrien, R. Gols, Koen Verhoeven, H. Vogel, Mirka Macel, H. Heidel-Fischer, K. Schramm, Wim H. van der Putten
    Exotic plants bring with them traits that evolved elsewhere into their new ranges. These traits may make them unattractive or even toxic to native herbivores, or vice versa. Here, interactions between two species of specialist (Pieris rapae and P. brassicae) and two species of generalist (Spodoptera exigua and Mamestra brassicae) insect herbivores were examined on two native crucifer species in the Netherlands, Brassica nigra and Sinapis arvensis, and an exotic, Bunias orientalis. Bu. orientalis originates in eastern Europe and western Asia but is now an invasive pest in many countries in central Europe. P. rapae, P. brassicae and S. exigua performed very poorly on Bu. orientalis, with close to 100% of larvae failing to pupate, whereas survival was much higher on the native plants. In choice experiments, the pierid butterflies preferred to oviposit on the native plants. Alternatively, M. brassicae developed very poorly on the native plants but thrived on Bu. orientalis. Further assays with a German Bu. orientalis population also showed that several specialist and generalist herbivores performed very poorly on this plant, with the exception of Spodoptera littoralis and M. brassicae. Bu. orientalis produced higher levels of secondary plant compounds (glucosinolates) than B. nigra but not S. arvensis but these do not appear to be important factors for herbivore development. Our results suggest that Bu. orientalis is a potential demographic ‘trap’ for some herbivores, such as pierid butterflies. However, through the effects of an evolutionary ‘lottery’, M. brassicae has found its way through the plant’s chemical ‘minefield’.