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.

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Analyzing Components of Productivity Growth Using the Bennet-Lowe Indicator: An Application to Welsh Sheep Farms
Ang, Frederic - \ 2019
American Journal of Agricultural Economics 101 (2019)4. - ISSN 0002-9092 - p. 1262 - 1276.
Bennet-Lowe indicator - data envelopment analysis - decomposition - distance function - total factor productivity - transitivity

This article introduces the Bennet-Lowe Total Factor Productivity (TFP) indicator. The proposed measure is difference-based, additively complete, and transitive. We also develop a general nonparametric framework to exhaustively decompose all Bennet-Type TFP indicators, including the one introduced here, into technical change, technical efficiency change, scale efficiency change, and mix efficiency change. This decomposition provides a powerful tool for policy makers to guide financial decisions on research and development, extension, subsidies, and price support. The empirical application focuses on the Welsh sheep sector for the years 2001-2014. The results show that in this 14-year period, Welsh sheep farms increased their TFP by 30.28% on average (2.33% p.a.). However, the exhaustive decomposition shows that TFP growth is not distributed equally across all farms, with an increasing divergence between front-runners and laggards. The negative values of scale efficiency change and mix efficiency change cast doubt on the current subsidy policies.

Data from: Relationships between fungal community composition in decomposing leaf litter and home-field advantage effects
Veen, G.F. ; Snoek, L.B. ; Bakx-Schotman, Tanja ; Wardle, David A. ; Putten, W.H. van der - \ 2019
decomposition - microbial community - fungi - sequencing - ITS - home-field advantage
Increasing evidence suggests that specific interactions between microbial decomposers and plant litter, named home field advantage (HFA), influence litter breakdown. However, we still have limited understanding of whether HFA relates to specific microbiota, and whether specialized microbes originate from the soil or from the leaf microbiome. Here, we disentangle the roles of soil origin, litter types, and the microbial community already present on the leaf litter in determining fungal community composition on decomposing leaf litter and HFA. We collected litters and associated soil samples from a secondary succession gradient ranging from herbaceous vegetation on recently abandoned ex‐arable fields to forest representing the end stage of succession. In a greenhouse, sterilized and unsterilized leaf litters were decomposed for 12 months in soils from early to late successional stages according to a full factorial design. At the end, we examined fungal community composition on the decomposing litter. Fungal communities on decomposed late‐successional litter in late‐successional soil differed from those in early‐ and mid‐successional stage litter and soil combinations. Soil source had the strongest impact on litter fungal composition when using sterilized litter, while the impact of litter type was strongest when using unsterilized litter. Overall, we observed HFA, as litter decomposition was accelerated in home soils. Increasing HFA did not relate to the dissimilarity in overall fungal composition, but there was increasing dissimilarity in the relative abundance of the most dominant fungal taxon between decomposing litter in home and away soils. We conclude that early, mid and late succession litter types did not exert strong selection effects on colonization by microorganisms from the soil species pool. Instead, fungal community composition on decomposing litter differed substantially between litter types for unsterilized litter, suggesting that the leaf microbiome, either directly or indirectly, is an important determinant of fungal community composition on decomposing leaves. HFA related most strongly to the abundance of the most dominant fungal taxa on the decomposing litter, suggesting that HFA may be attributed to some specific dominant fungi rather than to responses of the whole fungal community.
Data from: Warming enhances sedimentation and decomposition of organic carbon in shallow macrophyte-dominated systems with zero net effect on carbon burial
Velthuis, Mandy ; Kosten, S. ; Aben, Ralf ; Kazanjian, Garabet ; Hilt, Sabine ; Peeters, E.T.H.M. ; Donk, Ellen van; Bakker, Elisabeth S. - \ 2019
carbon cycle - decomposition - global warming - mineralization - phenology - primary production - sedimentation - submerged aquatic plant
Temperatures have been rising throughout recent decades and are predicted to rise further in the coming century. Global warming affects carbon cycling in freshwater ecosystems, which both emit and bury substantial amounts of carbon on a global scale. Currently, most studies focus on the effect of warming on overall carbon emissions from freshwater ecosystems, while net effects on carbon budgets may strongly depend on burial in sediments. Here, we tested whether year‐round warming increases the production, sedimentation, or decomposition of particulate organic carbon and eventually alters the carbon burial in a typical shallow freshwater system. We performed an indoor experiment in eight mesocosms dominated by the common submerged aquatic plant Myriophyllum spicatum testing two temperature treatments: a temperate seasonal temperature control and a warmed (+4°C) treatment (n = 4). During a full experimental year, the carbon stock in plant biomass, dissolved organic carbon in the water column, sedimented organic matter, and decomposition of plant detritus were measured. Our results showed that year‐round warming nearly doubled the final carbon stock in plant biomass from 6.9 ± 1.1 g C in the control treatment to 12.8 ± 0.6 g C (mean ± SE), mainly due to a prolonged growing season in autumn. DOC concentrations did not differ between the treatments, but organic carbon sedimentation increased by 60% from 96 ± 9.6 to 152 ± 16 g C m−2 year−1 (mean ± SE) from control to warm treatments. Enhanced decomposition of plant detritus in the warm treatment, however, compensated for the increased sedimentation. As a result, net carbon burial was 40 ± 5.7 g C m−2 year−1 in both temperature treatments when fluxes were combined into a carbon budget model. These results indicate that warming can increase the turnover of organic carbon in shallow macrophyte‐dominated systems, while not necessarily affecting net carbon burial on a system scale.
Relationships between fungal community composition in decomposing leaf litter and home-field advantage effects
Veen, G.F. ; Snoek, Basten L. ; Bakx-Schotman, Tanja ; Wardle, David A. ; Putten, Wim H. van der - \ 2019
Functional Ecology 33 (2019)8. - ISSN 0269-8463 - p. 1524 - 1535.
decomposition - fungi - ITS - microbial community - sequencing - succession

Increasing evidence suggests that specific interactions between microbial decomposers and plant litter, named home-field advantage (HFA), influence litter breakdown. However, we still have limited understanding of whether HFA relates to specific microbiota, and whether specialized microbes originate from the soil or from the leaf microbiome. Here, we disentangle the roles of soil origin, litter types and the microbial community already present on the leaf litter in determining fungal community composition on decomposing leaf litter and HFA. We collected litters and associated soil samples from a secondary succession gradient ranging from herbaceous vegetation on recently abandoned ex-arable fields to forest representing the end stage of succession. In a greenhouse, sterilized and unsterilized leaf litters were decomposed for 12 months in soils from early- to late-successional stages according to a full-factorial design. At the end, we examined fungal community composition on the decomposing litter. Fungal communities on decomposed late-successional litter in late-successional soil differed from those in early- and mid-successional stage litter and soil combinations. Soil source had the strongest impact on litter fungal composition when using sterilized litter, while the impact of litter type was strongest when using unsterilized litter. Overall, we observed HFA, as litter decomposition was accelerated in home soils. Increasing HFA did not relate to the dissimilarity in overall fungal composition, but there was increasing dissimilarity in the relative abundance of the most dominant fungal taxon between decomposing litter in home and away soils. We conclude that early-, mid- and late-succession litter types did not exert strong selection effects on colonization by micro-organisms from the soil species pool. Instead, fungal community composition on decomposing litter differed substantially between litter types for unsterilized litter, suggesting that the leaf microbiome, either directly or indirectly, is an important determinant of fungal community composition on decomposing leaves. HFA related most strongly to the abundance of the most dominant fungal taxa on the decomposing litter, suggesting that HFA may be attributed to some specific dominant fungi rather than to responses of the whole fungal community. A plain language summary is available for this article.

Warming enhances sedimentation and decomposition of organic carbon in shallow macrophyte-dominated systems with zero net effect on carbon burial
Velthuis, Mandy ; Kosten, Sarian ; Aben, Ralf ; Kazanjian, Garabet ; Hilt, Sabine ; Peeters, Edwin T.H.M. ; Donk, Ellen van; Bakker, Elisabeth S. - \ 2018
Global Change Biology 24 (2018)11. - ISSN 1354-1013 - p. 5231 - 5242.
carbon cycle - decomposition - global warming - mineralization - phenology - primary production - sedimentation - submerged aquatic plant

Temperatures have been rising throughout recent decades and are predicted to rise further in the coming century. Global warming affects carbon cycling in freshwater ecosystems, which both emit and bury substantial amounts of carbon on a global scale. Currently, most studies focus on the effect of warming on overall carbon emissions from freshwater ecosystems, while net effects on carbon budgets may strongly depend on burial in sediments. Here, we tested whether year-round warming increases the production, sedimentation, or decomposition of particulate organic carbon and eventually alters the carbon burial in a typical shallow freshwater system. We performed an indoor experiment in eight mesocosms dominated by the common submerged aquatic plant Myriophyllum spicatum testing two temperature treatments: a temperate seasonal temperature control and a warmed (+4°C) treatment (n = 4). During a full experimental year, the carbon stock in plant biomass, dissolved organic carbon in the water column, sedimented organic matter, and decomposition of plant detritus were measured. Our results showed that year-round warming nearly doubled the final carbon stock in plant biomass from 6.9 ± 1.1 g C in the control treatment to 12.8 ± 0.6 g C (mean ± SE), mainly due to a prolonged growing season in autumn. DOC concentrations did not differ between the treatments, but organic carbon sedimentation increased by 60% from 96 ± 9.6 to 152 ± 16 g C m−2 yaer−1 (mean ± SE) from control to warm treatments. Enhanced decomposition of plant detritus in the warm treatment, however, compensated for the increased sedimentation. As a result, net carbon burial was 40 ± 5.7 g C m−2 year−1 in both temperature treatments when fluxes were combined into a carbon budget model. These results indicate that warming can increase the turnover of organic carbon in shallow macrophyte-dominated systems, while not necessarily affecting net carbon burial on a system scale.

Data from: Variation in home-field advantage and ability in leaf litter decomposition across successional gradients
Veen, Ciska G.F. ; Keiser, Ashley D. ; Putten, W.H. van der; Wardle, David A. - \ 2018
decomposition - functional breadth - succession - soil - plant-litter feedback
1. It is increasingly recognized that interactions between plants and soil (a)biotic conditions can influence local decomposition processes. For example, decomposer communities may become specialized in breaking down litter of plant species that they are associated with, resulting in accelerated decomposition, known as ‘home-field advantage’ (HFA). Also, soils can vary inherently in their capacity to degrade organic compounds, known as ‘ability’. However, we have a poor understanding how environmental conditions drive the occurrence of HFA and ability. 2. Here, we studied how HFA and ability change across three types of successional gradients: coastal sand dunes (primary succession), inland drift sands (primary succession), and ex-arable fields (secondary succession). Across these gradients, litter quality (i.e., nutrient, carbon and lignin contents) increases with successional time for coastal dunes and decreases for the other two gradients. 3. We performed a 12-month reciprocal litter transplant experiment under greenhouse conditions using soils and litters collected from early-, mid-, and late-successional stages of each gradient. 4. We found that HFA and ability did not consistently shift with successional stage for all gradients, but were instead specific for each type of successional gradient. In coastal dunes HFA was positive for early-successional litter, in drift sands it was negative for mid-successional litter, and for ex-arable fields, HFA increased with successional time. Ability of decomposer communities was highest in mid-successional stages for coastal dunes and drift sands, but for ex-arable fields ability decreased throughout with successional time. High HFA was related to high litter C content and soil and organic matter content in soils and to low litter and soil nutrient concentrations. Ability did not consistently occur in successional stages with high or low litter quality. 5. Synthesis: Our findings show that specific environmental conditions, such as changes in litter or soil quality, along environmental gradients can shape the influence of HFA and ability on decomposition. In sites with strong HFA or ability, interactions between plants, litter and decomposer communities will be important drivers of nutrient cycling and hence have the potential to feedback to plant growth.
Data from: Winter cover crop legacy effects on litter decomposition act through litter quality and microbial community changes
Barel, J.M. ; Kuijper, T.W.M. ; Paul, Jos ; Boer, W. de; Cornelissen, Johannes H.C. ; Deyn, G.B. de - \ 2018
decomposition - microbial community composition - crop rotation - winter cover crop - legacy effects - standardised substrates - nitrogen cycling - carbon cycling - Avena sativa - Cichorium endivia - Lolium perenne - Trifolium repens - Raphanus sativus - Vicia sativa
1. In agriculture, winter cover crop (WCC) residues are incorporated into the soil to improve soil quality, as gradual litter decomposition can improve fertility. Decomposition rate is determined by litter quality, local soil abiotic and biotic properties. However, how these factors are interlinked and influenced by cropping history is unclear. 2. We grew WCC monocultures and mixtures in rotation with main crops Avena sativa and Cichorium endivia and tested how crop rotation influences WCC litter quality, abiotic and biotic soil conditions, and litter decomposition rates. To disentangle WCC litter quality effects from WCC soil legacy effects on decomposition, we tested how rotation history influences decomposition of standard substrates and explored the underlying mechanisms. 3. In a common environment (e.g. winter fallow plots), WCC decomposition rate constants (k) correlated negatively with litter C, lignin and, surprisingly, N content, due to strong positive correlations among these traits. Plots with a history of fast-decomposing WCCs exhibited faster decomposition of their own litters as well as of the standard substrates filter paper and rooibos tea, as compared to winter fallow plots. 4. WCC treatments differentially affected soil microbial biomass, as well as soil organic matter and mineral nitrogen content. WCC-induced soil changes affected decomposition rates. Depending on the main crop rotation treatment, legacy effects were attributed to biomass input of WCCs and their litter quality or changes in microbial biomass. 5. Synthesis and applications: These results demonstrate that decomposition in cropping systems is influenced directly through crop residues, as well as through crop-induced changes in soil biotic properties. Rotation history influences decomposition, wherein productive winter cover crops with low lignin content decompose fast and stimulate the turn-over of both own and newly added residues via their knock-on effect on the soil microbial community. Thus, winter cover crops have promise for sustainable carbon- and nutrient-cycling management through litter feedbacks.
Roots in the tundra : relations between climate warming and root biomass and implications for vegetation change and carbon dynamics
Wang, Peng - \ 2016
Wageningen University. Promotor(en): Frank Berendse, co-promotor(en): Monique Heijmans; Liesje Mommer. - Wageningen : Wageningen University - ISBN 9789462578609 - 168
roots - biomass - climatic change - vegetation - carbon - global warming - tundra - ecosystems - decomposition - siberia - wortels - biomassa - klimaatverandering - vegetatie - koolstof - opwarming van de aarde - toendra - ecosystemen - decompositie - siberië

Global climate has been warming up for the last decades and it will continue in this century. The Arctic is the part of the globe that warms fastest and is more sensitive to climate warming. Aboveground productivity of Arctic tundra has been shown to increase in response to warmer climates. However, belowground responses of tundra vegetation are still unclear. As the major part of plant biomass in tundra lies belowground, it is pivotal to investigate changes in the belowground parts of tundra vegetation for our understanding of climate warming effects on tundra ecosystems.

To get a general idea of how belowground plant biomass may change in a warmer climate, we synthesized published data on the belowground biomass of tundra vegetation across a broad gradient of mean annual air temperature from −20 to 0 °C. We found that aboveground biomass of tundra biomass indeed increases with mean annual temperature as well as summer air temperature, while belowground biomass did not show a significant relationship with temperature. The increases in the aboveground biomass were significantly larger than belowground biomass, resulting in reduced below/above ratios at higher temperatures. The shifted biomass allocation with temperature can influence the carbon dynamics of tundra ecosystems. Future tundra studies need to focus more on the species or functional type composition of belowground biomass and species or functional type specific belowground responses to climate warming.

To determine the seasonal changes and vertical distribution of root biomass of different plant functional types, we sampled roots at a Siberian tundra site in the early and late growing season, from vegetation types dominated by graminoids and shrubs respectively. We distinguished the roots of graminoids and shrubs, and found that shrub roots grew earlier and shallower than graminoid roots, which enables shrubs to gain advantage over graminoids at the early growing season when nutrient pulses occur during snowmelt and soil thaw. The deeper roots of graminoids can help them to be more competitive if climate warming induces more nutrient release in the deeper soil.

In a soil thawing and fertilization experiment, we further investigated the effects of increased thawing depth and nutrient supply in the upper soil, which can be the consequences of climate warming, on root biomass and its vertical distribution. In this study we distinguished between the roots of grasses, sedges, deciduous shrubs and evergreen shrubs. The study was done in a moist tussock tundra site with similar abundance of the different plant functional types. We found that only sedges benefited from the increased thawing depth, probably through their deepest root distribution among the four functional types, while the shrubs, which were shallower-rooted, benefited from the increased nutrient availability in the upper soil. The deep-rooted grasses had the highest plasticity in vertical root distribution, which enabled them also to benefit greatly from the fertilization. Our results show that tundra plants with different rooting strategies can show different responses to climate warming dependent on the relative warming impacts on the nutrient supply in shallow and deeper soil layers. This insight can help to predict future tundra vegetation dynamics.

The carbon balance of tundra ecosystems also depends on the decomposition of plant litter, particularly the root litter, which may account for a larger part of annual litter input than leaf litter in tundra ecosystems. Vegetation shifts also change litter quality which ultimately influences carbon dynamics. To investigate the differences in the decomposition of leaves and roots of graminoids and shrubs, we performed a litter transplant experiment. We found that although the decomposability of leaf litter did not differ between the graminoid and shrub, root decomposability might be lower for the shrub. However, this cannot be extrapolated to the overall decomposition in different vegetation types, as these different plant communities differ in rooting depths. We also found evidence of home-field advantage in the decomposition in Arctic tundra, and we show that the early stage of litter decomposition at our research site could be driven by the phosphorus concentration of the litter. To get a full understanding of the carbon balance of tundra ecosystems, much more efforts are needed to quantify litter input and decomposition.

In this thesis we show that belowground parts, which account for a major part of plant biomass in tundra, can show a different response to climate warming from aboveground parts. Belowground responses to climate warming can have crucial impacts on the competitive balance between tundra plants, and consequently result in vegetation shifts in tundra. Such shifts in species composition can have large effects on carbon dynamics through altered input and decomposability of plant litter, particularly root litter.

Endogeneity Corrected Stochastic Production Frontier and Technical Efficiency
Shee, A. ; Stefanou, S.E. - \ 2015
American Journal of Agricultural Economics 97 (2015)3. - ISSN 0002-9092 - p. 939 - 952.
manufacturing-industries - decomposition - inefficiency - growth - unobservables - regressors - reforms - model
A major econometric issue in estimating production parameters and technical efficiency is the possibility that some forces influencing production are only observed by the firm and not by the econometrician. Not only can this misspecification lead to a biased inference on the output elasticity of inputs, but it also provides a faulty measure of technical efficiency. We extend the Levinsohn and Petrin (2003) approach and provide an estimation algorithm to overcome the problem of endogenous input choice in stochastic production frontier estimation by generating consistent estimates of production parameters and technical efficiency. We apply the proposed method to a plant-level panel dataset from the Colombian food manufacturing sector for the period 1982-1998. This dataset provides the value of output and prices charged for each product, expenditures and prices paid for each material used, energy consumption in kilowatt per hour and energy prices, number of workers and payroll, and book values of capital stock. Empirical results find that the traditional stochastic production frontier tends to underestimate the output elasticity of capital and firm-level technical efficiency. The evidence in this research suggests that addressing the endogeneity issue matters in stochastic production frontier analysis.
Preferential degradation of polyphenols from Sphagnum – 4-Isopropenylphenol as a proxy for past hydrological conditions in Sphagnum-dominated peat
Schellekens, J. ; Bindler, R. ; Martinez Cortizas, A. ; McClymont, E.L. ; Abbott, G.D. ; Biester, H. ; Pontevedra Pombal, X. ; Buurman, P. - \ 2015
Geochimica et Cosmochimica Acta 150 (2015). - ISSN 0016-7037 - p. 74 - 89.
pyrolysis mass-spectrometry - soil organic-matter - ombrotrophic peat - decomposition - lignin - nitrogen - bogs - vegetation - plants - carbon
The net accumulation of remains of Sphagnum spp. is fundamental to the development of many peatlands. The effect of polyphenols from Sphagnum on decomposition processes is frequently cited but has barely been studied. The central area of the Rödmossamyran peatland (Sweden) is an open lawn that consists mostly of Sphagnum spp. with a very low contribution from vascular plants. In order to determine the effects of decay on sphagnum phenols, 53 samples of a 2.7 m deep core from this lawn were analysed with pyrolysis gas chromatography–mass spectrometry (pyrolysis-GC–MS) and compared with more traditional decomposition proxies such as C/N ratio, UV light transmission of alkaline peat extracts, and bulk density. Factor analysis of 72 quantified pyrolysis products suggested that the variation in 4-isopropenylphenol was largely determined by aerobic decomposition instead of Sphagnum abundance. In order to evaluate the effects of aerobic decay in Sphagnum peat, down-core records from different climatic regions were compared using molecular markers for plant biopolymers and C/N ratio. These included markers for lignin from vascular plants ((di)methoxyphenols), polyphenols from Sphagnum spp. (4-isopropenylphenol), and cellulose (levoglucosan). Our results indicate that polyphenols from Sphagnum are preferentially degraded over polysaccharides; consequently the variability of the marker for sphagnum acid, 4-isopropenylphenol, was found indicative of decomposition instead of reflecting the abundance of Sphagnum remains. The fact that 4-isopropenylphenol is aerobically degraded in combination with its specificity for Sphagnum spp. makes it a consistent indicator of past hydrological conditions in Sphagnum-dominated peat. In contrast, the variability of C/N records in Sphagnum-dominated peat was influenced by both vegetation shifts and decomposition, and the dominant effect differed between the studied peatlands. Our results provide direction for modelling studies that try to predict possible feedback mechanisms between peatlands and future climate change, and indicate that the focus in Sphagnum decay studies should be on carbohydrates rather than on phenolic compounds.
Data from: Plant species richness promotes soil carbon and nitrogen stocks in grasslands without legumes
Cong, W. ; Ruijven, J. van; Mommer, L. ; Deyn, G.B. de; Berendse, F. ; Hoffland, E. - \ 2014
biodiversity - ecosystem function - carbon sequestration - N mineralization - plant productivity - root biomass - decomposition
Data were collected in the 11-year grassland biodiversity experiment in Wageningen, the Netherlands, in 2010 and 2011. Abbreviated headlines are as follows: “”BLK”= block; “PT”= plot; "SR" = plant species richness; “MI” = monoculture identity (Ac = Agrostis capillaris; Ao = Anthoxanthum odoratum; Cj = Centaurea jacea; Fr = Festuca rubra; Hl = Holcus lanatus; Lv = Leucanthemum vulgare; Pl = Plantago lanceolata; Ra = Rumex acetosa); "AAB" = average aboveground biomass from 2000 to 2010 (g m-2); "RB" = standing root biomass (g fresh weight m-2) up to 50 cm depth in June 2010; "CS" = soil carbon stocks (g C m-2) in April 2011; "NS" = soil nitrogen stocks (g N m-2) in April 2011. "CD" = soil organic carbon decomposition (mg CO2-C kg-1 soil) measured in soil collected in April 2011; "NM" = potential net N mineralization rate (µg N kg-1 soil day-1) measured in soil collected in April 2011.
Mud, muddle and models in the knowledge value-chain to action on tropical peatland conservation
Noordwijk, M. van; Matthews, R.B. ; Agus, F. ; Farmer, J. ; Verchot, L. ; Hergoualc’h, K. ; Persch, S. ; Tata, H.L. ; Lusiana, B. ; Widayati, A. ; Dewi, S. - \ 2014
Mitigation and Adaptation Strategies for Global Change 19 (2014)6. - ISSN 1381-2386 - p. 887 - 905.
greenhouse-gas emissions - hydrological restoration - central kalimantan - carbon-dioxide - climate-change - decomposition - strategies - management - indonesia - soils
Tropical peatlands are known not only for their high, area-based, carbon emissions in response to land-use change but also as hot spots of debate about associated data uncertainties. Perspectives are still evolving on factors underlying the variability and uncertainty. Debate includes the ways of reducing emissions through rewetting, reforestation and agroforestry. A knowledge value-chain that is long and complex links (a) fundamental understanding of peat and peatland processes leading to sciencebased quantification and default values, (b) willingness and (c) ability to act towards emission reduction, and ultimately (d) to local, national and global actions that effectively provide rules, incentives and motivation to conserve peat and reduce emissions. We discuss this value chain, its stakeholders and issues that still remain partially unresolved.We conclude that, to shorten the denial and conspiracy-theory stages of debate that otherwise slow down steps B and C, networks of international and national scientists have to be involved at the early stage of identifying policysensitive environmental issues. Models span part of the knowledge value-chain but transition of analysis units requires specific attention, from soil volumes through area and commodity flows to opportunities for reductions. While drainage of peatlands triggers landscape-scale increases in emissions, factors beyond drainage depth, including nutrient supply, may have a major influence on decomposition rates. Attempts to disentangle the contributions of plant and peat-based respiration in surface flux measurements involve assumptions that cannot be easily verified in comparisons between land uses. With progress on A leading to new internationally accepted defaults and with resistance on step B reduced, the reality of C and lack of working solutions for D is currently constraining further progress.
Linkages between plant traits and soil ecology in the rhizosphere and through litter decomposition
Brolsma, K.M. - \ 2014
Wageningen University. Promotor(en): Ellis Hoffland, co-promotor(en): Ron de Goede. - Wageningen : Wageningen University - ISBN 9789462571068 - 112
bodemecologie - rizosfeer - ligstro - decompositie - wortels - bodembiologie - nematoda - solanum tuberosum - globodera pallida - biofumigatie - genotypen - soil ecology - rhizosphere - litter - decomposition - roots - soil biology - nematoda - solanum tuberosum - globodera pallida - biofumigation - genotypes
Interactions between microbial-feeding and predatory soil fauna trigger N2O emissions
Thakur, M.P. ; Groenigen, J.W. van; Kuiper, I. ; Deyn, G.B. de - \ 2014
Soil Biology and Biochemistry 70 (2014). - ISSN 0038-0717 - p. 256 - 262.
nitrogen mineralization - enchytraeid worms - trophic cascades - food webs - raw humus - decomposition - biodiversity - nitrification - oligochaeta - microarthropods
Recent research has shown that microbial-feeding invertebrate soil fauna species can significantly contribute to N2O emissions. However, in soil food webs microbial-feeding soil fauna interact with each other and with their predators, which affects microbial activity. To date we lack empirical tests of whether or not these interactions play a significant role in N2O emissions from soil. Therefore we studied how interactions between soil microbes, two groups of microbial-feeding soil fauna (enchytraeids and fungivorous mites) and their predators (predatory mites) affect soil N2O emissions. We hypothesized that: 1) the presence of two microbial-feeding fauna groups (enchytraeids and fungivorous mites) together increase N2O emissions more than when only a single group is present; and 2) the addition of predatory mites further enhances N2O emissions. We assembled soil food webs consisting of soil microbes, enchytraeids, fungivorous and predatory mites in microcosms with sandy loamy soil and sterilised hay as a substrate for the soil microbes. N2O emissions were measured during 56 days. We found no support for our first yet support for our second hypothesis. Addition of predatory mites to microcosms with enchytraeids and fungivorous mites increased N2O emissions significantly from 135.3 to 482.1 mg N m-2, which was also significantly higher than the control without fauna (83 mg N m-2) (P <0.001). In presence of enchytraeids, fungivorous and predatory mites, we found much higher nitrate availability at the time of the N2O peak on Day 35 (10.9 versus 5.5 mg N per kg soil without soil fauna), indicating that the major increase in N2O emissions in this treatment may be due to increased nitrification. Increased nitrification may be attributed to higher availability of N from the dead tissues of fungivorous mites and increased activity of the enchytraeids that might also have affected soil structure and contributed to increased N2O emissions. This study demonstrates the importance of interactions between microbial-feeding invertebrate soil fauna and their predators in understanding N2O emissions.
Soil pH and earthworms affect herbage nitrogen recovery from solid cattle manure in production grassland
Rashid, M.I. ; Goede, R.G.M. de; Corral Nunez, G.A. ; Brussaard, L. ; Lantinga, E.A. - \ 2014
Soil Biology and Biochemistry 68 (2014). - ISSN 0038-0717 - p. 1 - 8.
carbon-dioxide - decomposition - mineralization - acidification - population - mesocosms - emissions - litter - slurry - oxide
Long term use of inorganic fertilisers and reduced organic matter inputs have contributed to acidification of agricultural soils. This strongly affects the soil dwelling fauna and nutrient mineralisation. Organic fertilisers such as solid cattle manure (SCM) resurge as an option to overcome this acidification problem and to provide the required blend of essential macro- and micronutrients for plant growth. We assessed the effects of earthworm density (400 or 700 m-2) at two levels of soil pH (ambient and increased), with or without application of solid cattle manure (SCM), on herbage nitrogen (N) uptake, and CO2 and N2O emissions over a period of 134 days using undisturbed soil cores from an acid peat grassland in a mesocosm experiment. Liming proved to be beneficial for earthworm performance and grassland productivity. A higher soil pH and earthworm density resulted in a higher soil biological activity measured as soil respiration. The combined application of lime and earthworms increased herbage apparent N recovery from SCM by 83% compared to SCM only. In the manured treatments, herbage N uptake was positively correlated with earthworm density (R2 = 0.92). N2O emissions increased by 37% when SCM was applied compared to the unfertilised control. Following SCM application, the cumulative increase in herbage N uptake was almost ten times greater than the measured total N2O losses. No relationship was observed between earthworm density and level of N2O emission. N mineralisation and herbage N uptake from SCM in acidic peat grasslands were greatly stimulated by the combined increase in soil pH and earthworm density. This stimulated the activity of soil biota, resulting in an increased herbage N recovery from the applied SCM.
Diversity patterns of leaf-associated aquatic hyphomycetes along a broad latitudinal gradient
Jabiol, J. ; Bruder, A. ; Gessner, M.O. ; Makkonen, M. ; McKie, B.G. ; Peeters, E.T.H.M. ; Vos, V.C.A. ; Chauvet, E. - \ 2013
Fungal Ecology 6 (2013)5. - ISSN 1754-5048 - p. 439 - 448.
species-diversity - community structure - fungal communities - stream - litter - biodiversity - temperature - leaves - colonization - decomposition
Information about the global distribution of aquatic hyphomycetes is scarce, despite the primary importance of these fungi in stream ecosystem functioning. In particular, the relationship between their diversity and latitude remains unclear, due to a lack of coordinated surveys across broad latitudinal ranges. This study is a first report on latitudinal patterns of aquatic hyphomycete diversity associated with native leaf-litter species in five streams located along a gradient extending from the subarctic to the tropics. Exposure of leaf litter in mesh bags of three different mesh sizes facilitated assessing the effects of including or excluding different size-classes of litter-consuming invertebrates. Aquatic hyphomycete evenness was notably constant across all sites, whereas species richness and diversity, expressed as the Hill number, reached a maximum at mid-latitudes (Mediterranean and temperate streams). These latitudinal patterns were consistent across litter species, despite a notable influence of litter identity on fungal communities at the local scale. As a result, the bell-shaped distribution of species richness and Hill diversity deviated markedly from the latitudinal patterns of most other groups of organisms. Differences in the body-size distribution of invertebrate communities colonizing the leaves had no effect on aquatic hyphomycete species richness, Hill diversity or evenness, but invertebrates could still influence fungal communities by depleting litter, an effect that was not captured by the design of our experiment. (C) 2013 Elsevier Ltd and The British Mycological Society. All rights reserved.
Soil invertebrate fauna affect N2O emissions from soil
Kuiper, I. ; Deyn, G.B. de; Thakur, M.P. ; Groenigen, J.W. van - \ 2013
Global Change Biology 19 (2013)9. - ISSN 1354-1013 - p. 2814 - 2825.
greenhouse-gas emissions - nitrous-oxide - nutrient mineralization - n mineralization - forest soil - carbon - ecosystems - denitrification - decomposition - enchytraeids
Nitrous oxide (N2O) emissions from soils contribute significantly to global warming. Mitigation of N2O emissions is severely hampered by a lack of understanding of its main controls. Fluxes can only partly be predicted from soil abiotic factors and microbial analyses – a possible role for soil fauna has until now largely been overlooked. We studied the effect of six groups of soil invertebrate fauna and tested the hypothesis that all of them increase N2O emissions, although to different extents. We conducted three microcosm experiments with sandy soil and hay residue. Faunal groups included in our experiments were as follows: fungal-feeding nematodes, mites, springtails, potworms, earthworms and isopods. In experiment I, involving all six faunal groups, N2O emissions declined with earthworms and potworms from 78.4 (control) to 37.0 (earthworms) or 53.5 (potworms) mg N2O-N m-2. In experiment II, with a higher soil-to-hay ratio and mites, springtails and potworms as faunal treatments, N2O emissions increased with potworms from 51.9 (control) to 123.5 mg N2O-N m-2. Experiment III studied the effect of potworm density; we found that higher densities of potworms accelerated the peak of the N2O emissions by 5 days (P <0.001), but the cumulative N2O emissions remained unaffected. We propose that increased soil aeration by the soil fauna reduced N2O emissions in experiment I, whereas in experiment II N2O emissions were driven by increased nitrogen and carbon availability. In experiment III, higher densities of potworms accelerated nitrogen and carbon availability and N2O emissions, but did not increase them. Overall, our data show that soil fauna can suppress, increase, delay or accelerate N2O emissions from soil and should therefore be an integral part of future N2O studies.
Soil food web properties explain ecosystem services across European land use systems
Vries, F.T. de; Thebault, E.M.C. ; Liiri, M. ; Birkhofer, K. ; Tsiafouli, M. ; Bjornlund, L. ; Jorgensen, H.B. ; Brady, M.V. ; Christensen, S. ; Ruiter, P.C. de; Hertefeldt, T. d'; Frouz, J. ; Hedlund, K. ; Hemerik, L. ; Hol, W.H.G. ; Hotes, S. ; Mortimer, S.R. ; Setälä, H. ; Sgardelis, S.P. ; Uteseny, K. ; Putten, W.H. van der; Wolters, V. ; Bardgett, R.D. - \ 2013
Proceedings of the National Academy of Sciences of the United States of America 110 (2013)35. - ISSN 0027-8424 - p. 14296 - 14301.
nitrogen mineralization - carbon sequestration - bacterial community - mycorrhizal fungi - biomass - scale - intensification - decomposition - biodiversity - agriculture
Intensive land use reduces the diversity and abundance of many soil biota, with consequences for the processes that they govern and the ecosystem services that these processes underpin. Relationships between soil biota and ecosystem processes have mostly been found in laboratory experiments and rarely are found in the field. Here, we quantified, across four countries of contrasting climatic and soil conditions in Europe, how differences in soil food web composition resulting from land use systems (intensive wheat rotation, extensive rotation, and permanent grassland) influence the functioning of soils and the ecosystem services that they deliver. Intensive wheat rotation consistently reduced the biomass of all components of the soil food web across all countries. Soil food web properties strongly and consistently predicted processes of C and N cycling across land use systems and geographic locations, and they were a better predictor of these processes than land use. Processes of carbon loss increased with soil food web properties that correlated with soil C content, such as earthworm biomass and fungal/bacterial energy channel ratio, and were greatest in permanent grassland. In contrast, processes of N cycling were explained by soil food web properties independent of land use, such as arbuscular mycorrhizal fungi and bacterial channel biomass. Our quantification of the contribution of soil organisms to processes of C and N cycling across land use systems and geographic locations shows that soil biota need to be included in C and N cycling models and highlights the need to map and conserve soil biodiversity across the world.
Environmental change impacts on the C- and N-cycle of European forests: a model comparison study
Cameron, D.R. ; Oijen, M. Van; Werner, C. ; Butterbach-Bahl, K. ; Grote, R. ; Haas, E. ; Heuvelink, G.B.M. ; Kiese, R. ; Kros, J. ; Kuhnert, M. ; Leip, A. ; Reinds, G.J. ; Reuter, H.I. ; Schelhaas, M.J. ; Vries, W. de; Yeluripati, J. - \ 2013
Biogeosciences 10 (2013). - ISSN 1726-4170 - p. 1751 - 1773.
nitrogen limitation - temperate forests - carbon budget - soils - n2o - ecosystems - agriculture - emissions - growth - decomposition
Forests are important components of the greenhouse gas balance of Europe. There is considerable uncertainty about how predicted changes to climate and nitrogen deposition will perturb the carbon and nitrogen cycles of European forests and thereby alter forest growth, carbon sequestration and N2O emission. The present study aimed to quantify the carbon and nitrogen balance, including the exchange of greenhouse gases, of European forests over the period 2010–2030, with a particular emphasis on the spatial variability of change. The analysis was carried out for two tree species: European beech and Scots pine. For this purpose, four different dynamic models were used: BASFOR, DailyDayCent, INTEGRATOR and Landscape-DNDC. These models span a range from semi-empirical to complex mechanistic. Comparison of these models allowed assessment of the extent to which model predictions depended on differences in model inputs and structure. We found a European average carbon sink of 0.160 ± 0.020 kgC m-2 yr-1 (pine) and 0.138 ± 0.062 kgC m-2 yr-1 (beech) and N2O source of 0.285 ± 0.125 kgN ha-1 yr-1 (pine) and 0.575 ± 0.105 kgN ha-1 yr-1 (beech). The European average greenhouse gas potential of the carbon sink was 18 (pine) and 8 (beech) times that of the N2O source. Carbon sequestration was larger in the trees than in the soil. Carbon sequestration and forest growth were largest in central Europe and lowest in northern Sweden and Finland, N. Poland and S. Spain. No single driver was found to dominate change across Europe. Forests were found to be most sensitive to change in environmental drivers where the drivers were limiting growth, where changes were particularly large or where changes acted in concert. The models disagreed as to which environmental changes were most significant for the geographical variation in forest growth and as to which tree species showed the largest rate of carbon sequestration. Pine and beech forests were found to have differing sensitivities to environmental change, in particular the response to changes in nitrogen and precipitation, with beech forest more vulnerable to drought. There was considerable uncertainty about the geographical location of N2O emissions. Two of the models BASFOR and LandscapeDNDC had largest emissions in central Europe where nitrogen deposition and soil nitrogen were largest, whereas the two other models identified different regions with large N2O emission. N2O emissions were found to be larger from beech than pine forests and were found to be particularly sensitive to forest growth.
Soil biota and nitrogen cycling in production grasslands with different fertilisation histories
Rashid, M.I. - \ 2013
Wageningen University. Promotor(en): Lijbert Brussaard, co-promotor(en): Egbert Lantinga; Ron de Goede. - S.l. : s.n. - ISBN 9789461735485 - 192
stikstofkringloop - bodemfauna - mineralisatie - rundveemest - decompositie - bodeminvertebraten - bodem ph - aardwormen - graslanden - bodembiologie - nitrogen cycle - soil fauna - mineralization - cattle manure - decomposition - soil invertebrates - soil ph - earthworms - grasslands - soil biology
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