Staff Publications

Staff Publications

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    'Staff publications' is the digital repository of Wageningen University & Research

    'Staff publications' contains references to publications authored by Wageningen University staff from 1976 onward.

    Publications authored by the staff of the Research Institutes are available from 1995 onwards.

    Full text documents are added when available. The database is updated daily and currently holds about 240,000 items, of which 72,000 in open access.

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    What happens in Europe stays in Europe : apparent evolution by an invader does not help at home
    Pal, Robert W. ; Maron, John L. ; Nagy, David U. ; Waller, Lauren P. ; Tosto, Ambra ; Liao, Huixuan ; Callaway, Ragan M. - \ 2020
    Ecology (2020). - ISSN 0012-9658
    biogeography - common garden experiment - competition - EICA hypothesis - invasion - reintroduction - Solidago gigantea - transcontinental research

    Some invasive plant species rapidly evolve greater size and/or competitive ability in their nonnative ranges. However, it is not well known whether these traits transfer back to the native range, or instead represent genotype-by-environment interactions where traits are context specific to communities in the new range where the evolution occurred. Insight into transferability vs. context specificity can be tested using experiments performed with individuals from populations from the native and nonnative ranges of exotic invasive species. Using a widespread invasive plant species in Europe, Solidago gigantea, we established reciprocal common garden experiments in the native range (Montana, North America; n = 4) and the nonnative range (Hungary, Europe; n = 4) to assess differences in size, vegetative shoot number, and herbivory between populations from the native and nonnative ranges. In a greenhouse experiment, we also tested whether the inherent competitive ability of genotypes from 15 native and 15 invasive populations differed when pitted against 11 common native North American competitors. In common gardens, plants from both ranges considered together produced five times more biomass, grew four times taller, and developed five times more rhizomes in the nonnative range garden compared to the native range garden. The interaction between plant origin and the common garden location was highly significant, with plants from Hungary performing better than plants from Montana when grown in Hungary, and plants from Montana performing better than plants from Hungary when grown in Montana. In the greenhouse, there were no differences in the competitive effects and responses of S. gigantea plants from the two ranges when grown with North American natives. Our results suggest that S. gigantea might have undergone rapid evolution for greater performance abroad, but if so, this response does not translate to greater performance at home.

    Competition influences tree growth, but not mortality, across environmental gradients in Amazonia and tropical Africa
    Rozendaal, Danaë M.A. ; Phillips, Oliver L. ; Lewis, Simon L. ; Affum-Baffoe, Kofi ; Alvarez-Davila, Esteban ; Andrade, Ana ; Aragão, Luiz E.O.C. ; Araujo-Murakami, Alejandro ; Baker, Timothy R. ; Bánki, Olaf ; Brienen, Roel J.W. ; Camargo, José Luis C. ; Comiskey, James A. ; Djuikouo Kamdem, Marie Noël ; Fauset, Sophie ; Feldpausch, Ted R. ; Killeen, Timothy J. ; Laurance, William F. ; Laurance, Susan G.W. ; Lovejoy, Thomas ; Malhi, Yadvinder ; Marimon, Beatriz S. ; Marimon Junior, Ben Hur ; Marshall, Andrew R. ; Neill, David A. ; Núñez Vargas, Percy ; Pitman, Nigel C.A. ; Poorter, Lourens ; Reitsma, Jan ; Silveira, Marcos ; Sonké, Bonaventure ; Sunderland, Terry ; Taedoumg, Hermann ; Steege, Hans ter; Terborgh, John W. ; Umetsu, Ricardo K. ; Heijden, Geertje M.F. van der; Vilanova, Emilio ; Vos, Vincent ; White, Lee J.T. ; Willcock, Simon ; Zemagho, Lise ; Vanderwel, Mark C. - \ 2020
    Ecology 101 (2020)7. - ISSN 0012-9658
    climatic water deficit - competition - forest dynamics - mortality - neighborhood effects - soil fertility - trait-based models - tree growth - tropical forest - wood density

    Competition among trees is an important driver of community structure and dynamics in tropical forests. Neighboring trees may impact an individual tree’s growth rate and probability of mortality, but large-scale geographic and environmental variation in these competitive effects has yet to be evaluated across the tropical forest biome. We quantified effects of competition on tree-level basal area growth and mortality for trees ≥10-cm diameter across 151 ~1-ha plots in mature tropical forests in Amazonia and tropical Africa by developing nonlinear models that accounted for wood density, tree size, and neighborhood crowding. Using these models, we assessed how water availability (i.e., climatic water deficit) and soil fertility influenced the predicted plot-level strength of competition (i.e., the extent to which growth is reduced, or mortality is increased, by competition across all individual trees). On both continents, tree basal area growth decreased with wood density and increased with tree size. Growth decreased with neighborhood crowding, which suggests that competition is important. Tree mortality decreased with wood density and generally increased with tree size, but was apparently unaffected by neighborhood crowding. Across plots, variation in the plot-level strength of competition was most strongly related to plot basal area (i.e., the sum of the basal area of all trees in a plot), with greater reductions in growth occurring in forests with high basal area, but in Amazonia, the strength of competition also varied with plot-level wood density. In Amazonia, the strength of competition increased with water availability because of the greater basal area of wetter forests, but was only weakly related to soil fertility. In Africa, competition was weakly related to soil fertility and invariant across the shorter water availability gradient. Overall, our results suggest that competition influences the structure and dynamics of tropical forests primarily through effects on individual tree growth rather than mortality and that the strength of competition largely depends on environment-mediated variation in basal area.

    N2Africa in northern Ghana : Context to the recent quantitative Impact StudyA qualitative impact assessment in four villages
    Thuijsman, E.C. ; Braber, Harmen den - \ 2019
    Wageningen : N2Africa (N2Africa project report 119) - 44 p.
    feedback - learning - labour - collaboration - competition - Impact - evaluation - Ghana
    In May and June 2019 we visited four villages in northern Ghana where N2Africa has been active and which have been included in N2Africa’s Impact Study. With the aim of adding qualitative context to the quantitative Impact Study, we discussed the experiences with N2Africa in an open way in individual interviews and focus group discussions with villagers.

    When N2Africa commenced in the study villagers, many villagers were eager to learn about new farming practices that would generate a good cash return. Most respondents sounded very content about what N2Africa had brought them: technology options to experiment with that resulted in production increases, especially for soyabean. New varieties were much-appreciated, although they were considered too input-demanding sometimes. Very many respondents liked the method of fertiliser application in a furrow next to a row of seeds. This method was now used on legumes as well as on other crops for efficient fertiliser use. Respondents did not know or care much about inoculants, and they were considered difficult to access. Fertiliser application and row planting were considered very good but tedious practices and a larger workforce was required to get the work done, compared to broadcasting inputs. Labour was sought first in the family, and then among friends and labour groups. Labourers are scarce at the start of the growing season, when everyone is occupied at the same time. The starchy staple crops received priority in terms of land, labour and cash investment. If farmers had investment capacity left, they could invest in legumes as well.

    N2Africa could only work with a limited number of villagers directly, and it differed per village whether information was pro-actively shared with people that were not directly involved. Those who took most initiative by themselves were most likely to be involved in projects and to benefit most from them. Respondents recommended future agricultural development projects to focus on improving varieties (short-duration, drought-resistant) and on mechanisation (land preparation and processing).
    Narrow-wide-row planting pattern increases the radiation use efficiency and seed yield of intercrop species in relay-intercropping system
    Raza, Muhammad Ali ; Feng, Ling Yang ; Werf, Wopke van der; Cai, Gao Ren ; Khalid, Muhammad Hayder Bin ; Iqbal, Nasir ; Hassan, Muhammad Jawad ; Meraj, Tehseen Ahmad ; Naeem, Muhammd ; Khan, Imran ; Ur Rehman, Sana ; Ansar, Muhammad ; Ahmed, Mukhtar ; Yang, Feng ; Yang, Wenyu - \ 2019
    Food and Energy Security 8 (2019)3. - ISSN 2048-3694
    competition - intercropping - land equivalent ratio - radiation use efficiency

    Planting arrangements affect radiation use efficiency (RUE) and competitiveness of intercrop species in intercropping systems. Here, we reveal that narrow-wide-row planting arrangement in maize-soybean relay-intercropping system increases the dry matter and competitiveness of soybean, increased the RUE of maize and soybean, and compensates the yield loss of maize by substantially increasing the yield of soybean. In this field study, maize was planted with soybean in different planting arrangements (P1, 20:180, P2, 40:160; P3, 60:140, and P4, 80:120) of relay intercropping, all the relay-intercropping treatments were compared with sole crops of maize (SM) and soybean (SS). Results showed that P1 improved the total RUE 3.26 g/MJ (maize RUE + soybean RUE) of maize and soybean in relay-intercropping system. Compared to P4, treatment P1 increased the soybean competition ratio (CR) values (by 55%) but reduced the maize CR values (by 29%), which in turn significantly improved the yield of soybean by maintaining the maize yield. Generally, in P1, soybean produced 82% of SS yield, and maize produced 88% of SM yield, and it achieved the land equivalent ratio of 1.7. These results suggest that by maintaining the appropriate planting distances between maize and soybean we can improve the competitiveness and yield of intercrop species in relay-intercropping system.

    Ecological significance of light quality in optimizing plant defence
    Douma, Jacob C. ; Vries, Jorad de; Poelman, Erik H. ; Dicke, Marcel ; Anten, Niels P.R. ; Evers, Jochem B. - \ 2019
    Plant, Cell & Environment 42 (2019)3. - ISSN 0140-7791 - p. 1065 - 1077.
    Brassica nigra - competition - functional–structural plant modelling - growth-defence trade-off - herbivory - plant defence - red to far-red ratio - shade avoidance

    Plants balance the allocation of resources between growth and defence to optimize fitness in a competitive environment. Perception of neighbour-detection cues, such as a low ratio of red to far-red (R:FR) radiation, activates a suite of shade-avoidance responses that include stem elongation and upward leaf movement, whilst simultaneously downregulating defence. This downregulation is hypothesized to benefit the plant either by mediating the growth-defence balance in favour of growth in high plant densities or, alternatively, by mediating defence of individual leaves such that those most photosynthetically productive are best protected. To test these hypotheses, we used a 3D functional–structural plant model of Brassica nigra that mechanistically simulates the interactions between plant architecture, herbivory, and the light environment. Our results show that plant-level defence expression is a strong determinant of plant fitness and that leaf-level defence mediation by R:FR can provide a fitness benefit in high densities. However, optimal plant-level defence expression does not decrease monotonically with plant density, indicating that R:FR mediation of defence alone is not enough to optimize defence between densities. Therefore, assessing the ecological significance of R:FR-mediated defence is paramount to better understand the evolution of this physiological linkage and its implications for crop breeding.

    Carbonate Adsorption to Ferrihydrite : Competitive Interaction with Phosphate for Use in Soil Systems
    Mendez, Juan C. ; Hiemstra, Tjisse - \ 2019
    ACS Earth and Space Chemistry 3 (2019)1. - ISSN 2472-3452 - p. 129 - 141.
    CD model - competition - ferrihydrite - goethite - ion adsorption - nanoparticles - solubility - surface complexation

    Carbonate (CO3) interacts with Fe-(hydr)oxide nanoparticles, affecting the availability and geochemical cycle of other important oxyanions in nature. Here, we studied the carbonate-phosphate interaction in closed systems with freshly prepared ferrihydrite (Fh), using batch experiments that cover a wide range of pH values, ionic strength, and CO3 and PO4 concentrations. The surface speciation of CO3 has been assessed by interpreting the ion competition with the Charge Distribution (CD) model, using CD coefficients derived from MO/DTF optimized geometries. Adsorption of CO3 occurs predominately via formation of bidentate inner-sphere complexes, either (=FeO)2CO or (=FeO)2CO··Na+. The latter complex is electrostatically promoted at high pH and in the presence of adsorbed PO4. Additionally, a minor complex is present at high CO3 loadings. The CD model, solely parametrized by measuring the pH-dependent PO4 adsorption as a function of the CO3 concentration, successfully predicts the CO3 adsorption to Fh in single-ion systems. The adsorption affinity of CO3 to Fh is higher than to goethite, particularly at high pH and CO3 loadings due to the enhanced formation (=FeO)2CO··Na+. The PO4 adsorption isotherm in 0.5 M NaHCO3 can be well described, being relevant for assessing the reactive surface area of the natural oxide fraction with soil extractions and CD modeling. Additionally, we have evaluated the enhanced Fh solubility due to Fe(III)-CO3 complex formation and resolved a new species (Fe(CO3)2(OH)2 3(aq)), which is dominant in closed systems at high pH. The measured solubility of our Fh agrees with the size-dependent solubility predicted using the surface Gibbs free energy of Fh.

    Ecological interactions shape the adaptive value of plant defence : Herbivore attack versus competition for light
    Vries, Jorad de; Evers, Jochem B. ; Dicke, Marcel ; Poelman, Erik H. - \ 2019
    Functional Ecology 33 (2019)1. - ISSN 0269-8463 - p. 129 - 138.
    Brassica nigra - competition - ecological costs - functional-structural plant modelling - growth-defence trade-off - herbivore interactions - herbivory - plant - plant defence

    Plants defend themselves against diverse communities of herbivorous insects. This requires an investment of limited resources, for which plants also compete with neighbours. The consequences of an investment in defence are determined by the metabolic costs of defence as well as indirect or ecological costs through interactions with other organisms. These ecological costs have a potentially strong impact on the evolution of defensive traits, but have proven to be difficult to quantify. We aimed to quantify the relative impact of the direct and indirect or ecological costs and benefits of an investment in plant defence in relation to herbivory and intergenotypic competition for light. Additionally, we evaluated how the benefits of plant defence balance its costs in the context of herbivory and intergenotypic competition. To this end, we utilised a functional-structural plant (FSP) model of Brassica nigra that simulates plant growth and development, morphogenesis, herbivory and plant defence. In the model, a simulated investment in defences affected plant growth by competing with other plant organs for resources and affected the level and distribution of herbivore damage. Our results show that the ecological costs of intergenotypic competition for light are highly detrimental to the fitness of defended plants, as it amplifies the size difference between defended and undefended plants. This leads to herbivore damage counteracting the effects of intergenotypic competition under the assumption that herbivore damage scales with plant size. Additionally, we show that plant defence relies on reducing herbivore damage rather than the dispersion of herbivore damage, which is only beneficial under high levels of herbivore damage. We conclude that the adaptive value of plant defence is highly dependent on ecological interactions and is predominantly determined by the outcome of competition for light.

    Phenotypic plasticity as a clue for invasion success of the submerged aquatic plant Elodea nuttallii
    Szabó, S. ; Peeters, E.T.H.M. ; Várbíró, G. ; Borics, G. ; Lukács, B.A. - \ 2019
    Plant Biology 21 (2019)1. - ISSN 1435-8603 - p. 54 - 63.
    Alien - aquatic plant - competition - light - macrophyte - nitrogen

    Two closely related alien submerged aquatic plants were introduced into Europe. The new invader (Elodea nuttallii) gradually displaced E. canadensis even at sites where the latter was well established. The aim of the study was to evaluate the combined effects of environmental factors on several phenotypic characteristics of the two Elodea species, and to relate these phenotypic characteristics to the invasion success of E. nuttallii over E. canadensis. In a factorial design, Elodea plants were grown in aquaria containing five different nitrogen concentrations and incubated at five different light intensities. We used six functional traits (apical shoot RGR), total shoot RGR, relative elongation, root length, lateral spread, branching degree) to measure the environmental response of the species. We calculated plasticity indices to express the phenotypic differences between species. Light and nitrogen jointly triggered the development of phenotypic characteristics that make E. nuttallii a more successful invader in eutrophic waters than E. canadensis. The stronger invader showed a wider range of phenotypic plasticity. The apical elongation was the main difference between the two species, with E. nuttallii being more than two times longer than E. canadensis. E. canadensis formed dense side shoots even under high shade and low nitrogen levels, whereas E. nuttallii required higher light and nitrogen levels. We found that under more eutrophic conditions, E. nuttallii reach the water surface sooner than E. canadensis and through intensive branching outcompetes all other plants including E. canadensis. Our findings support the theory that more successful invaders have wider phenotypic plasticity.

    Data from: Plant functional diversity and nutrient availability can improve restoration of floating fens via facilitation, complementarity and selection effects
    Zuidam, Jeroen P. van; Leeuwen, Casper H.A. van; Bakker, Elisabeth S. ; Verhoeven, J.T.A. ; Ijff, Stéphanie D. ; Peeters, E.T.H.M. ; Zuidam, B.G. van; Soons, Merel B. - \ 2018
    University Utrecht
    assisted colonization - competition - ecosystem restoration - rich fens - rhizome formation - terrestrialization - wetlands - peat formation
    Peat-forming wetlands, and particularly floating fens forming the initial stages of these ecosystems, are globally declining due to excavation, dehydration and eutrophication. Restoration of these valuable ecosystems typically involves re-establishment of early-successional open-water stages with oligotrophic conditions that are characteristic for these systems. However, restoration success is notoriously limited and a potential solution may be to initiate succession by re-introduction of target plant species. Knowledge is needed on (a) which plant functional groups should be re-introduced to stimulate fen formation; and (b) how to manage nutrient levels during restoration, considering that plant growth may be slow in oligotrophic conditions. 2. We hypothesized that (1) increasing functional diversity of introduced species would stimulate the formation of peat-forming target communities, their biomass accumulation and expansion onto open water; and that (2) nutrient availability would mediate the relative contribution of specific functional groups to these effects. We experimentally investigated this in 36 artificial outdoor ponds by manipulating plant functional diversity (clonal dominants, clonal stress-tolerators and interstitials) on constructed rafts with fen-forming communities and subjected these to a range of nutrient loadings over two years. 3. Increasing functional diversity as well as increasing nutrient loadings had stimulating effects on plant biomass accumulation, cover formation and rhizome growth onto open water. Both complementarity (due to niche partitioning or facilitation) and selection effects were mechanisms underlying the diversity effect, with a constant relative importance over the entire range of nutrient availabilities. Different functional groups were important for biomass production at different nutrient availabilities. Rhizome formation by clonal stress-tolerators contributed disproportionately to open water colonisation, identifying this functional group as key across all nutrient levels. 4. Synthesis and applications Restoration of floating fen communities (1) can be stimulated during the first two years by introducing a high functional diversity of plant species, including fast-growing clonal species, clonal stress-tolerators and interstitials, which facilitate each other, (2) is dependent on the presence of clonal stress-tolerators such as Calla palustris, Comarum palustre and Menyanthes trifoliata for expansion onto the open water, (3) can start under a wide range of water nutrient levels, including eutrophic conditions.11-Jul-2018
    Data from: Modelling the co-evolution of indirect genetic effects and inherited variability
    Marjanovic, J. ; Mulder, H.A. ; Rönnegård, L. ; Bijma, P. - \ 2018
    Wageningen University & Research
    inherited variability - canalization - indirect genetic effects - social interactions - competition
    When individuals interact, their phenotypes may be affected by genes in their social partners, a phenomenon known as Indirect Genetic Effects (IGEs). In aquaculture species and some plants, competition not only affects trait levels of individuals, but also inflates variation of trait values among individuals. Variability of trait values has been studied as a quantitative trait in itself, and is often referred to as inherited variability. Although the observed phenotypic relationship between competition and variability suggests an underlying genetic relationship, models of IGE and inherited variability do not allow for such relationship. Models of trait levels show IGEs may considerably change heritable variation in trait values. Currently, we lack the tools to investigate whether this result extends to inherited variability. Here we present a model that integrates IGEs and inherited variability. In this model, the target phenotype, say growth rate, is a function of genetic and environmental effects of the focal individual and of the difference in trait values between the social partner and the focal individual, multiplied by a regression coefficient. The regression coefficient is a genetic trait which is measure of cooperation; a negative value indicates competition, a positive value cooperation, and an increasing value due to selection indicates the evolution of cooperation. Our simulations show that the model results in increased variability of body weight with increase of competition. When competition decreases, variability becomes significantly smaller. Our findings suggest we may have been overlooking an entire level of genetic variation in variability, the one due to IGEs
    Relative importance of competition and plant–soil feedback, their synergy, context dependency and implications for coexistence
    Lekberg, Ylva ; Bever, James D. ; Bunn, Rebecca A. ; Callaway, Ragan M. ; Hart, Miranda M. ; Kivlin, Stephanie N. ; Klironomos, John ; Larkin, Beau G. ; Maron, John L. ; Reinhart, Kurt O. ; Remke, Michael ; Putten, Wim H. van der - \ 2018
    Ecology Letters 21 (2018)8. - ISSN 1461-023X - p. 1268 - 1281.
    Additive interaction - coexistence - competition - facilitation - meta-analysis - mutualist - pathogen - plant–soil feedback - resource gradient - soil biota

    Plants interact simultaneously with each other and with soil biota, yet the relative importance of competition vs. plant–soil feedback (PSF) on plant performance is poorly understood. Using a meta-analysis of 38 published studies and 150 plant species, we show that effects of interspecific competition (either growing plants with a competitor or singly, or comparing inter- vs. intraspecific competition) and PSF (comparing home vs. away soil, live vs. sterile soil, or control vs. fungicide-treated soil) depended on treatments but were predominantly negative, broadly comparable in magnitude, and additive or synergistic. Stronger competitors experienced more negative PSF than weaker competitors when controlling for density (inter- to intraspecific competition), suggesting that PSF could prevent competitive dominance and promote coexistence. When competition was measured against plants growing singly, the strength of competition overwhelmed PSF, indicating that the relative importance of PSF may depend not only on neighbour identity but also density. We evaluate how competition and PSFs might interact across resource gradients; PSF will likely strengthen competitive interactions in high resource environments and enhance facilitative interactions in low-resource environments. Finally, we provide a framework for filling key knowledge gaps and advancing our understanding of how these biotic interactions influence community structure.

    Elucidating the interaction between light competition and herbivore feeding patterns using functional-structural plant modelling
    Vries, Jorad De; Poelman, Erik H. ; Anten, Niels ; Evers, Jochem B. - \ 2018
    Annals of Botany 121 (2018)5. - ISSN 0305-7364 - p. 1019 - 1031.
    Brassica - competition - functional-structural plant modelling - growth-defence trade-off - herbivore specialization - herbivory - nigra - plant-herbivore interactions - red far-red ratio
    Background and Aims Plants usually compete with neighbouring plants for resources such as light as well as defend themselves against herbivorous insects. This requires investment of limiting resources, resulting in optimal resource distribution patterns and trade-offs between growth- and defence-related traits. A plant's competitive success is determined by the spatial distribution of its resources in the canopy. The spatial distribution of herbivory in the canopy in turn differs between herbivore species as the level of herbivore specialization determines their response to the distribution of resources and defences in the canopy. Here, we investigated to what extent competition for light affects plant susceptibility to herbivores with different feeding preferences. Methods To quantify interactions between herbivory and competition, we developed and evaluated a 3-D spatially explicit functional-structural plant model for Brassica nigra that mechanistically simulates competition in a dynamic light environment, and also explicitly models leaf area removal by herbivores with different feeding preferences. With this novel approach, we can quantitatively explore the extent to which herbivore feeding location and light competition interact in their effect on plant performance. Key Results Our results indicate that there is indeed a strong interaction between levels of plant-plant competition and herbivore feeding preference. When plants did not compete, herbivory had relatively small effects irrespective of feeding preference. Conversely, when plants competed, herbivores with a preference for young leaves had a strong negative effect on the competitiveness and subsequent performance of the plant, whereas herbivores with a preference for old leaves did not. Conclusions Our study predicts how plant susceptibility to herbivory depends on the composition of the herbivore community and the level of plant competition, and highlights the importance of considering the full range of dynamics in plant-plant-herbivore interactions.
    Plant community evenness responds to spatial plant–soil feedback heterogeneity primarily through the diversity of soil conditioning
    Wubs, E.R.J. ; Bezemer, T.M. - \ 2018
    Functional Ecology 32 (2018)2. - ISSN 0269-8463 - p. 509 - 521.
    competition - plant diversity - plant–soil interactions - spatial heterogeneity
    Functional Ecology published by John Wiley & Sons Ltd on behalf of British Ecological Society. 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. 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. Our data show that PSFs promoted a higher plant evenness when the soil was conditioned by multiple species (mixed-conditioned) than 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. 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. 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. A plain language summary is available for this article.
    Data from: Plant community evenness responds to spatial plant-soil feedback heterogeneity primarily through the diversity of soil conditioning
    Wubs, E.R.J. ; Bezemer, T.M. - \ 2017
    NIOO-KNAW
    competition - plant-soil interactions - spatial heterogeneity - plant diversity - Agrostis capillaris - Festuca rubra - Hypochaeris radicata - Jacobaea vulgaris - Lotus corniculatus - Trifolium pratense
    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. 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.
    Functional trait dissimilarity drives both species complementarity and competitive disparity
    Wagg, Cameron ; Ebeling, Anne ; Roscher, Christiane ; Ravenek, Janneke ; Bachmann, Dörte ; Eisenhauer, Nico ; Mommer, Liesje ; Buchmann, Nina ; Hillebrand, Helmut ; Schmid, Bernhard ; Weisser, Wolfgang W. - \ 2017
    Functional Ecology 31 (2017)12. - ISSN 0269-8463 - p. 2320 - 2329.
    biodiversity - community ecology - competition - Jena experiment - trait-based experiment (TBE)
    Niche complementarity and competitive disparity are driving mechanisms behind plant community assembly and productivity. Consequently, there is great interest in predicting species complementarity and their competitive differences from their functional traits as dissimilar species may compete less and result in more complete use of resources. Here we assessed the role of trait dissimilarities for species complementarity and competitive disparities within an experimental gradient of plant species richness and functional trait dissimilarity. Communities were assembled using three pools of grass and forb species based on a priori knowledge of traits related to (1) above- and below-ground spatial differences in resource acquisition, (2) phenological differences or (3) both. Complementarity and competitive disparities were assessed by partitioning the overyielding in mixed species communities into species complementarity and dominance effects. Community overyielding and the underlying complementarity and competitive dominance varied strongly among the three plant species pools. Overyielding and complementarity were greatest among species that were assembled based on their variation in both spatial and phenological traits. Competitive dominance was greatest when species were assembled based on spatial resource acquisition traits alone. In communities that were assembled based on species variation in only spatial or phenological traits, greater competitive dominance was predicted by greater differences in SLA and flowering initiation respectively, while greater complementarity was predicted by greater dissimilarity in leaf area and flowering senescence respectively. Greater differences in leaf area could also be linked to greater species complementarity in communities assembled based on variation in both phenological and spatial traits, but trait dissimilarity was unrelated to competitive dominance in these communities. Our results indicate that complementarity and competitive disparity among species are both driven by trait dissimilarities. However, the identity of the traits that drives the complementarity and competitive disparity depends on the trait variation among species that comprise the community. Moreover, we demonstrate that communities assembled with the greater variation in both spatial and phenological traits show the greatest complementarity among species. A plain language summary is available for this article.
    Call for projects 'Nieuwe Energie voor het Landschap I+II' (Event)
    Stremke, Sven - \ 2017
    Energy - landscape - design - competition
    Stimulieringsfonds Creative Industrie: Jury membership
    Above- and below-ground responses of four tundra plant functional types to deep soil heating and surface soil fertilization
    Wang, Peng ; Limpens, Juul ; Mommer, Liesje ; Ruijven, Jasper van; Nauta, Ake L. ; Berendse, Frank ; Schaepman-Strub, Gabriela ; Blok, Daan ; Maximov, Trofim C. ; Heijmans, Monique M.P.D. - \ 2017
    Journal of Ecology 105 (2017)4. - ISSN 0022-0477 - p. 947 - 957.
    accelerated thawing - active layer thickness - Arctic tundra - climate warming - competition - nutrient availability - plant functional types - root biomass - vegetation composition - vertical root distribution

    Climate warming is faster in the Arctic than the global average. Nutrient availability in the tundra soil is expected to increase by climate warming through (i) accelerated nutrient mobilization in the surface soil layers, and (ii) increased thawing depths during the growing season which increases accessibility of nutrients in the deeper soil layers. Both processes may initiate shifts in tundra vegetation composition. It is important to understand the effects of these two processes on tundra plant functional types. We manipulated soil thawing depth and nutrient availability at a Northeast-Siberian tundra site to investigate their effects on above- and below-ground responses of four plant functional types (grasses, sedges, deciduous shrubs and evergreen shrubs). Seasonal thawing was accelerated with heating cables at c. 15 cm depth without warming the surface soil, whereas nutrient availability was increased in the surface soil by adding slow-release NPK fertilizer at c. 5 cm depth. A combination of these two treatments was also included. This is the first field experiment specifically investigating the effects of accelerated thawing in tundra ecosystems. Deep soil heating increased the above-ground biomass of sedges, the deepest rooted plant functional type in our study, but did not affect biomass of the other plant functional types. In contrast, fertilization increased above-ground biomass of the two dwarf shrub functional types, both of which had very shallow root systems. Grasses showed the strongest response to fertilization, both above- and below-ground. Grasses were deep-rooted, and they showed the highest plasticity in terms of vertical root distribution, as grass root distribution shifted to deep and surface soil in response to deep soil heating and surface soil fertilization respectively. Synthesis. Our results indicate that increased thawing depth can only benefit deep-rooted sedges, while the shallow-rooted dwarf shrubs, as well as flexible-rooted grasses, take advantage of increased nutrient availability in the upper soil layers. Our results suggest that grasses have the highest root plasticity, which enables them to be more competitive in rapidly changing environments. We conclude that root vertical distribution strategies are important for vegetation responses to climate-induced increases in soil nutrient availability in Arctic tundra, and that future shifts in vegetation composition will depend on the balance between changes in thawing depth and nutrient availability in the surface soil.

    Benefits from living together? Clades whose species use similar habitats may persist as a result of eco-evolutionary feedbacks
    Prinzing, Andreas ; Ozinga, Wim A. ; Brändle, Martin ; Courty, Pierre Emmanuel ; Hennion, Françoise ; Labandeira, Conrad ; Parisod, Christian ; Pihain, Mickael ; Bartish, Igor V. - \ 2017
    New Phytologist 213 (2017)1. - ISSN 0028-646X - p. 66 - 82.
    assembly of present and fossil communities - competition - conservation biology - enemy pressure and mutualism of coexisting species - evolution and conservatism - hybridization - niche breadth

    (Table presented.). Summary: Recent decades have seen declines of entire plant clades while other clades persist despite changing environments. We suggest that one reason why some clades persist is that species within these clades use similar habitats, because such similarity may increase the degree of co-occurrence of species within clades. Traditionally, co-occurrence among clade members has been suggested to be disadvantageous because of increased competition and enemy pressure. Here, we hypothesize that increased co-occurrence among clade members promotes mutualist exchange, niche expansion or hybridization, thereby helping species avoid population decline from environmental change. We review the literature and analyse published data for hundreds of plant clades (genera) within a well-studied region and find major differences in the degree to which species within clades occupy similar habitats. We tentatively show that, in clades for which species occupy similar habitats, species tend to exhibit increased co-occurrence, mutualism, niche expansion, and hybridization – and rarely decline. Consistently, throughout the geological past, clades whose species occupied similar habitats often persisted through long time-spans. Overall, for many plant species, the occupation of similar habitats among fellow clade members apparently reduced their vulnerability to environmental change. Future research should identify when and how this previously unrecognized eco-evolutionary feedback operates.

    Data from: Above and belowground responses of four tundra plant functional types to deep soil heating and surface soil fertilization
    Wang, Peng ; Limpens, J. ; Mommer, L. ; Ruijven, J. van; Nauta, A.L. ; Berendse, F. ; Schaepman-Strub, Gabriela ; Blok, Daan ; Maximov, Trofim C. ; Heijmans, M.M.P.D. - \ 2016
    Wageningen University & Research
    active layer thickness - Arctic tundra - climate warming - competition - nutrient availability - plant functional types - root biomass - vertical root distribution - vegetation composition - accelerating thawing - Betula nana - Eriophorum vaginatum - Vaccinium vitis-idaea - Rhododendron tomentosum - Calamagrostis holmii - Arctagrostis latifolia - Carex bigelowii
    1.Climate warming is faster in the Arctic than the global average. Nutrient availability in the tundra soil is expected to increase by climate warming through 1) accelerated nutrient mobilization in the surface soil layers, and 2) increased thawing depths during the growing season which increases accessibility of nutrients in the deeper soil layers. Both processes may initiate shifts in tundra vegetation composition. It is important to understand the effects of these two processes on tundra plant functional types. 2.We manipulated soil thawing depth and nutrient availability at a Northeast-Siberian tundra site to investigate their effects on above and belowground responses of four plant functional types (grasses, sedges, deciduous shrubs and evergreen shrubs). Seasonal thawing was accelerated with heating cables at ~15 cm depth without warming the surface soil, whereas nutrient availability was increased in the surface soil by adding slow-release NPK fertilizer at ~5 cm depth. A combination of these two treatments was also included. This is the first field experiment specifically investigating the effects of accelerated thawing in tundra ecosystems. 3.Deep soil heating increased the aboveground biomass of sedges, the deepest-rooted plant functional type in our study, but did not affect biomass of the other plant functional types. In contrast, fertilization increased aboveground biomass of the two dwarf shrub functional types, which both had very shallow root systems. Grasses showed the strongest response to fertilization, both above and belowground. Grasses were deep-rooted, and they showed the highest plasticity in terms of vertical root distribution, as grass root distribution shifted to deep and surface soil in response to deep soil heating and surface soil fertilization, respectively. 4.Synthesis - Our results indicate that increased thawing depth can only benefit deep-rooted sedges, while the shallow-rooted dwarf shrubs as well as flexible-rooted grasses take advantage of increased nutrient availability in the upper soil layers. Our results suggest that grasses have the highest root plasticity, which enables them to be more competitive in rapidly changing environments. We conclude that root vertical distribution strategies are important for vegetation responses to climate-induced increases in soil nutrient availability in Arctic tundra, and that future shifts in vegetation composition will depend on the balance between changes in thawing depth and nutrient availability in the surface soil.
    Data from: Individual variation in winter supplementary food consumption and its consequences for reproduction in wild birds.
    Crates, R.A. ; Firth, J.A. ; Farine, D.R. ; Garroway, C.J. ; Kidd, Lindall R. ; Aplin, L.M. ; Radersma, Reinder ; Milligan, Nicole D. ; Voelkl, Bernhard ; Culina, Antica ; Verhelst, B.L. ; Hinde, C.A. ; Sheldon, B.C. - \ 2016
    Wageningen University & Research
    competition - foraging - Passive Integrated Transponder - Parus major - Cyanistes caeruleus
    The provision of wild birds with supplementary food has increased substantially over recent decades. While it is assumed that provisioning birds is beneficial, supplementary feeding can have detrimental ‘carry-over’ effects on reproductive traits. Due to difficulties in monitoring individual feeding behaviour, assessing how individuals within a population vary in their exploitation of supplementary food resources has been limited. Quantifying individual consumption of supplementary food is necessary to understand the operation of carry-over effects at the individual level. We used Radio Frequency Identification (RFID) technology and automated feeders to estimate individual consumption of supplementary winter food in a large wild population of great tits Parus major and blue tits Cyanistes caeruleus. Using these data, we identified demographic factors that explained individual variation in levels of supplementary food consumption. We also tested for carry-over effects of supplementary food consumption on recruitment, reproductive success and a measure of survival. Individual variation in consumption of supplementary food was explained by differences between species, ages, sexes and years. Individuals were consistent across time in their usage of supplementary resources. We found no strong evidence that the extent of supplementary food consumption directly influenced subsequent fitness parameters. Such effects may instead result from supplementary food influencing population demographics by enhancing the survival and subsequent breeding of less competitive individuals, which reduce average breeding parameters and increase density-dependent competition. Carry-over effects of supplementary feeding are not universal and may depend upon the temporal availability of the food provided. Our study demonstrates how RFID systems can be used to examine individual-level behaviour with minimal effects on fitness.
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