- H. Duyts (1)
- G. Everaert (1)
- B. Frey (1)
- D.J. Gwiazdowicz (2)
- Wim H. Putten Van Der (1)
- C.R. Janssen (1)
- A.A. Koelmans (1)
- Martijn L. Vandegehuchte (4)
- J. Mees (1)
- R. Ochoa-Hueso (1)
- D.S. Page-Dumroese (2)
- W.H. Putten van der (2)
- W.H. Putten Van Der (1)
- Ursina Raschein (1)
- M. Rijcke De (1)
- A.C. Risch (2)
- Martin Schütz (3)
- M. Schütz (1)
- M.L. Vandegehuchte (1)
- S. Zimmermann (1)
- Stephan Zimmermann (1)
Size-dependent loss of aboveground animals differentially affects grassland ecosystem coupling and functions
Risch, A.C. ; Ochoa-Hueso, R. ; Putten, W.H. van der; Bump, J.K. ; Busse, M.D. ; Frey, B. ; Gwiazdowicz, D.J. ; Page-Dumroese, D.S. ; Vandegehuchte, M.L. ; Zimmermann, S. ; Schütz, M. - \ 2018
Nature Communications 9 (2018)1. - ISSN 2041-1723
Increasing evidence suggests that community-level responses to human-induced biodiversity loss start with a decrease of interactions among communities and between them and their abiotic environment. The structural and functional consequences of such interaction losses are poorly understood and have rarely been tested in real-world systems. Here, we analysed how 5 years of progressive, size-selective exclusion of large, medium, and small vertebrates and invertebrates—a realistic scenario of human-induced defaunation—impacts the strength of relationships between above- and belowground communities and their abiotic environment (hereafter ecosystem coupling) and how this relates to ecosystem functionality in grasslands. Exclusion of all vertebrates results in the greatest level of ecosystem coupling, while the additional loss of invertebrates leads to poorly coupled ecosystems. Consumer-driven changes in ecosystem functionality are positively related to changes in ecosystem coupling. Our results highlight the importance of invertebrate communities for maintaining ecological coupling and functioning in an increasingly defaunated world.
Risk assessment of microplastics in the ocean: modelling approach and first conclusions
Everaert, G. ; Cauwenberghe, L. van; Rijcke, M. De; Koelmans, A.A. ; Mees, J. ; Vandegehuchte, Martijn L. ; Janssen, C.R. - \ 2018
Environmental Pollution 242 (2018)B. - ISSN 0269-7491 - p. 1930 - 1938.
We performed an environmental risk assessment for microplastics (<5 mm) in the marine environment by estimating the order of magnitude of the past, present and future concentrations based on global plastic production data. In 2100, from 9.6 to 48.8 particles m−3 are predicted to float around in the ocean, which is a 50-fold increase compared to the present-day concentrations. From a meta-analysis with effect data available in literature, we derived a safe concentration of 6650 buoyant particles m−3 below which adverse effects are not likely to occur. Our risk assessment (excluding the potential role of microplastics as chemical vectors) suggests that on average, no direct effects of free-floating microplastics in the marine environment are to be expected up to the year 2100. Yet, even today, the safe concentration can be exceeded in sites that are heavily polluted with buoyant microplastics. In the marine benthic compartment between 32 and 144 particles kg−1 dry sediment are predicted to be present in the beach deposition zone. Despite the scarcity of effect data, we expect adverse ecological effects along the coast as of the second half of the 21st century. From then ambient concentrations will start to outrange the safe concentration of sedimented microplastics (i.e. 540 particles kg−1 sediment). Additional ecotoxicological research in which marine species are chronically exposed to realistic environmental microplastic concentration series are urgently needed to verify our findings.
Aboveground mammal and invertebrate exclusions cause consistent changes in soil food webs of two subalpine grassland types, but mechanisms are system-specific
Vandegehuchte, Martijn L. ; Putten, Wim H. Van Der; Duyts, Henk ; Schütz, Martin ; Risch, Anita C. - \ 2017
Oikos 126 (2017)2. - ISSN 0030-1299 - p. 212 - 223.
Ungulates, smaller mammals, and invertebrates can each affect soil biota through their influence on vegetation and soil characteristics. However, direct and indirect effects of the aboveground biota on soil food webs remain to be unraveled. We assessed effects of progressively excluding aboveground large-, medium- and small-sized mammals as well as invertebrates on soil nematode diversity and feeding type abundances in two subalpine grassland types: short- and tall-grass vegetation. We explored pathways that link exclusions of aboveground biota to nematode feeding type abundances via changes in plants, soil environment, soil microbial biomass, and soil nutrients.
In both vegetation types, exclusions caused a similar shift toward higher abundance of all nematode feeding types, except plant feeders, lower Shannon diversity, and lower evenness. These effects were strongest when small mammals, or both small mammals and invertebrates were excluded in addition to excluding larger mammals. Exclusions resulted in a changed abiotic soil environment that only affected nematodes in the short-grass vegetation. In each vegetation type, exclusion effects on nematode abundances were mediated by different drivers related to plant quantity and quality. In the short-grass vegetation, not all exclusion effects on omni–carnivorous nematodes were mediated by the abundance of lower trophic level nematodes, suggesting that omni–carnivores also depended on other prey than nematodes.
We conclude that small aboveground herbivores have major impacts on the soil food web of subalpine short- and tall-grass ecosystems. Excluding aboveground animals caused similar shifts in soil nematode assemblages in both subalpine vegetation types, however, mechanisms turned out to be system-specific.
Data from: Aboveground mammal and invertebrate exclusions cause consistent changes in soil food webs of two subalpine grassland types, but mechanisms are system-specific
Vandegehuchte, Martijn L. ; Putten, W.H. van der; Duyts, H. ; Schütz, Martin ; Risch, Anita C. - \ 2016
soil ecology - above-belowground interactions - herbivory
Data_OIK-03341.R2.csv contains the data on nematode feeding type abundances and community indices, as well as the data used in the Structural Equation Models of the progressive aboveground mammal and invertebrate exclusion effects on the abundance of bacterivorous, fungivorous, plant-feeding and omni-carnivorous nematode abundance via pathways of plants, soil nutrients, soil microbial biomass, and soil environment in both short- and tall-grass vegetation
Aboveground vertebrate and invertebrate herbivore impact on net N mineralization in subalpine grasslands
Risch, A.C. ; Schütz, Martin ; Vandegehuchte, Martijn L. ; Putten, W.H. Van Der; Duyts, Henk ; Raschein, Ursina ; Gwiazdowicz, D.J. ; Busse, M.D. ; Page-Dumroese, D.S. ; Zimmermann, Stephan - \ 2015
Ecology 96 (2015)12. - ISSN 0012-9658 - p. 3312 - 3322.
Above-belowground interactions - Exclosure types - Functionally different herbivores - Herbivory - Nutrient cycling - Plant biomass - Plant properties - Soil arthropods - Soil mites - Soil properties - Subalpine grasslands - Switzerland
Aboveground herbivores have strong effects on grassland nitrogen (N) cycling. They can accelerate or slow down soil net N mineralization depending on ecosystem productivity and grazing intensity. Yet, most studies only consider either ungulates or invertebrate herbivores, but not the combined effect of several functionally different vertebrate and invertebrate herbivore species or guilds. We assessed how a diverse herbivore community affects net N mineralization in subalpine grasslands. By using size-selective fences, we progressively excluded large, medium, and small mammals, as well as invertebrates from two vegetation types, and assessed how the exclosure types (ET) affected net N mineralization. The two vegetation types differed in long-term management (centuries), forage quality, and grazing history and intensity. To gain a more mechanistic understanding of how herbivores affect net N mineralization, we linked mineralization to soil abiotic (temperature; moisture; NO3 -, NH4 +, and total inorganic N concentrations/pools; C, N, P concentrations; pH; bulk density), soil biotic (microbial biomass; abundance of collembolans, mites, and nematodes) and plant (shoot and root biomass; consumption; plant C, N, and fiber content; plant N pool) properties. Net N mineralization differed between ET, but not between vegetation types. Thus, shortterm changes in herbivore community composition and, therefore, in grazing intensity had a stronger effect on net N mineralization than long-term management and grazing history. We found highest N mineralization values when only invertebrates were present, suggesting that mammals had a negative effect on net N mineralization. Of the variables included in our analyses, only mite abundance and aboveground plant biomass explained variation in net N mineralization among ET. Abundances of both mites and leaf-sucking invertebrates were positively correlated with aboveground plant biomass, and biomass increased with progressive exclusion. The negative impact of mammals on net N mineralization may be related partially to (1) differences in the amount of plant material (litter) returned to the belowground subsystem, which induced a positive bottom-up effect on mite abundance, and (2) alterations in the amount and/or distribution of dung, urine, and food waste. Thus, our results clearly show that short-term alterations of the aboveground herbivore community can strongly impact nutrient cycling within ecosystems independent of long-term management and grazing history.