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Top-down effects of four herbivore groups of different body size on above- and belowground properties in grassland ecosystems of variable productivity

English title Top-down effects of four herbivore groups of different body size on above- and belowground properties in grassland ecosystems of variable productivity
Applicant Risch Anita Christina
Number 122009
Funding scheme Project funding (Div. I-III)
Research institution Swiss Federal Research Inst. WSL Direktion
Institution of higher education Swiss Federal Institute for Forest, Snow and Landscape Research - WSL
Main discipline Ecology
Start/End 01.04.2009 - 28.02.2013
Approved amount 276'827.00
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All Disciplines (4)

Discipline
Ecology
Botany
Zoology
Pedology

Keywords (19)

Grazer-grassland interactions; trophic levels; above- and belowground ecosystem properties; ecosystem productivity; body size; food web; microbial community composition; plant species abundance; vertebrate and invertebrate herbivores; competition; facilitation; grazing; aboveground plant biomass; root biomass; microbial biomass; vegetation biomass; changes in plant species abundance; vegetation quality; high-elevation grassland ecosystem

Lay Summary (English)

Lead
Lay summary
The aboveground plant biomass produced in grassland ecosystems supports a multitude of vertebrate and invertebrate herbivores. Vegetation productivity, vegetation nutritional quality, plant species richness, soil physical, chemical and biological properties or ecosystem nutrient cycling, in turn, can be affected by the quantity, quality and the composition of forage that herbivores ingest. The response of an ecosystem to grazing, is however, highly dependent on the productivity of the ecosystem studied and the grazing intensity it receives. The grazing intensity and the amount/quality of biomass consumed by a herbivore group, in turn, are generally related to body size: large ungulates, for example, consume greater proportions of the total biomass produced, but generally are less selective than small vertebrate and invertebrate herbivores. Consequently, the sum of the effects of herbivores on ecosystem parameters depends on the density and composition of the herbivore community as well as the productivity of an ecosystem. However, most of the research conducted on grazer-grassland interactions only considered one or two herbivore groups of different body size. We are aware of only four studies that assessed how three or more herbivore groups of different body size interacted with the grassland ecosystem they inhabit. In these studies the investigations were restricted to the effects of herbivores i) on plant-animal interactions (two trophic levels) in one or several vegetation types only or ii) plant-animal-soil interactions in a single vegetation type only. Consequently, our understanding on the functioning of grazer-grassland interactions considering the combined effect of several herbivore groups on vegetation types of different productivity and across several trophic levels is still very limited.To assess a multitude of potential interactions in a grassland ecosystem we established an exclosure experiment in the Swiss National Park in spring 2009. With this experiment we determine single and combined effects of four herbivore groups of distinctively different body size and foraging behavior in two different vegetation types on plant, root and microbial biomass and nutrient content (nitrogen and phosphorus) as well as on the composition of plant and microbial communities. The herbivore groups include large (red deer and chamois), medium (marmots), and small (small rodents) vertebrate as well as invertebrate herbivores.
Direct link to Lay Summary Last update: 21.02.2013

Responsible applicant and co-applicants

Employees

Publications

Publication
Indirect short- and long-term effects of aboveground invertebrate and vertebrate herbivores on soil microarthropod communities
Vandegehuchte Martijn (2015), Indirect short- and long-term effects of aboveground invertebrate and vertebrate herbivores on soil microarthropod communities, in PLoS one, 10, e0118679.
Does the aboveground herbivore assemblage influence soil bacterial community structure in subalpine grasslands?
Hodel Melanie (2014), Does the aboveground herbivore assemblage influence soil bacterial community structure in subalpine grasslands?, in Microbial Ecology, 68, 584-595.
Linkages between grazing history and herbivore exclusion on decomposition rates in mineral soils of subalpine grasslands
Haynes AG, Schuetz M, Buchmann N, Page-Dumroese DS, Busse M, Risch AC (2014), Linkages between grazing history and herbivore exclusion on decomposition rates in mineral soils of subalpine grasslands, in Plant and Soil, 374, 579-591.
The response of soil CO2 fluxes to progressively excluding vertebrate and invertebrate herbivores depends on ecosystem type
Risch AC, Haynes AG, Busse M, Filli F, Schuetz M (2013), The response of soil CO2 fluxes to progressively excluding vertebrate and invertebrate herbivores depends on ecosystem type, in Ecosystems, 16(7), 1192-1202.
Impact of wild ungulate grazing on Orthoptera abundance and diversity in subalpine grasslands
Spalinger Lena C., Haynes Alan G., Schütz Martin, Risch Anita C. (2012), Impact of wild ungulate grazing on Orthoptera abundance and diversity in subalpine grasslands, in Insect Conservation and Diversity, 5, 444-452.

Collaboration

Group / person Country
Types of collaboration
Syracuse University United States of America (North America)
- in-depth/constructive exchanges on approaches, methods or results
- Publication
USDA Forest Service, Rocky Mountain Research Station United States of America (North America)
- in-depth/constructive exchanges on approaches, methods or results
- Publication
- Research Infrastructure
Schweizerischer Nationalpark Switzerland (Europe)
- in-depth/constructive exchanges on approaches, methods or results
- Publication
- Research Infrastructure
- Exchange of personnel
WSL Birmensdorf, Rhizosphären Prozesse Switzerland (Europe)
- in-depth/constructive exchanges on approaches, methods or results
- Publication
- Research Infrastructure
USDA Forest Service, Pacific North West Research Station United States of America (North America)
- in-depth/constructive exchanges on approaches, methods or results
- Publication
- Research Infrastructure

Scientific events

Active participation

Title Type of contribution Title of article or contribution Date Place Persons involved
Gordon Research Conferences on Plant-Animal-Interactions Poster Does size matter? Vegetation response to exclusion of herbivore guilds from large ungulates to insects 24.02.2013 Ventura, CA, USA, United States of America Haynes Alan; Filli Flurin; Schütz Martin; Risch Anita Christina;
Annual Meeting of the British Ecological Society Individual talk Does size matter? Vegetation quantity and quality responses to the exclusion of herbivore guilds from large ungulates to invertebrates 18.12.2012 Birmingham, United Kingdom, Great Britain and Northern Ireland Risch Anita Christina; Haynes Alan; Schütz Martin;
ETH Grassland Seminar Individual talk Does size matter? Soil decomposition responses to exclusion of herbivore guilds from large ungulates to insects 21.10.2011 ETH Zürich, Switzerland Risch Anita Christina; Filli Flurin; Schütz Martin; Haynes Alan;
ETH Grassland Seminar Individual talk DOES SIZE REALLY MATTER? THE EFFECTS OF HERBIVORE BODYSIZE ON ECOSYSTEM PROCESSES 20.12.2010 ETH Zürich, Schweiz, Switzerland Schütz Martin; Risch Anita Christina; Haynes Alan;
IPAS PhD Symposium Poster The bigger the better? 28.10.2010 Rüschlikon, Schweiz, Switzerland Haynes Alan; Risch Anita Christina; Schütz Martin;


Self-organised

Title Date Place
Workshop Community Ecology 29.08.2011 Zernez, Schweiz, Switzerland

Knowledge transfer events

Active participation

Title Type of contribution Date Place Persons involved
Regionaltagung Südbünden Talk 26.06.2012 Zernez, Switzerland Risch Anita Christina; Filli Flurin;


Self-organised

Title Date Place
Pensioniertenausflug Swissair OK Quer 06.07.2012 Nationalpark, Switzerland
Ausbildung für Infomobil-Mitarbeiter Schweizerischer Nationalpark 12.07.2011 Zernez, Switzerland
Ausbildung für Infomobil-Mitarbeiter Schweizerischer Nationalpark 30.06.2011 Nationalpark, Schweiz, Switzerland

Communication with the public

Communication Title Media Place Year
Other activities Drei Beiträge im Atlas des Schweizerischen Nationalparks International Rhaeto-Romanic Switzerland German-speaking Switzerland Western Switzerland Italian-speaking Switzerland 2013
Media relations: print media, online media Forscht in Graubünden: Alan Haynes Bündner Woche German-speaking Switzerland Rhaeto-Romanic Switzerland 2012
Print (books, brochures, leaflets) Jahresbericht WSL German-speaking Switzerland 2011
New media (web, blogs, podcasts, news feeds etc.) Projektseite deutsch Web German-speaking Switzerland 2011
New media (web, blogs, podcasts, news feeds etc.) Projektseite Englisch Web German-speaking Switzerland Western Switzerland Rhaeto-Romanic Switzerland Italian-speaking Switzerland International 2011
Talks/events/exhibitions Trophische Interaktionen im Nationalpark - Feldführung für die Nationalparkadministration German-speaking Switzerland 2011
Talks/events/exhibitions Trophische Interaktionen im Nationalpark - Feldführung für die Parkadministration German-speaking Switzerland 2011
Talks/events/exhibitions ALPARC annual meeting International German-speaking Switzerland Italian-speaking Switzerland Western Switzerland Rhaeto-Romanic Switzerland 2010
Print (books, brochures, leaflets) Cratschla German-speaking Switzerland 2010
Talks/events/exhibitions Naturama German-speaking Switzerland 2010
Media relations: radio, television Einstein SF1 German-speaking Switzerland 2009
Print (books, brochures, leaflets) Informationsblatt Landschaft (WSL) German-speaking Switzerland 2009

Associated projects

Number Title Start Funding scheme
140939 The consequences of grazing: linking above- and belowground arthropod biodiversity, multi-trophic community structure and ecosystem functioning across grasslands of different productivity 01.03.2013 Project funding (Div. I-III)

Abstract

The aboveground plant biomass produced in grassland ecosystems supports a multitude of vertebrate and invertebrate herbivores. Vegetation productivity, vegetation nutritional quality, plant species richness, soil physical, chemical and biological properties or ecosystem nutrient cycling, in turn, can be affected by the quantity, quality and the composition of forage that herbivores ingest. The response of an ecosystem to grazing, is however, highly dependent on the productivity of the ecosystem studied and the grazing intensity it receives. The grazing intensity and the amount/quality of biomass consumed by a herbivore group, in turn, are generally related to body size: large ungulates, for example, consume greater proportions of the total biomass produced, but generally are less selective than small vertebrate and invertebrate herbivores. Consequently, the sum of the effects of herbivores on ecosystem parameters depends on the density and composition of the herbivore community as well as the productivity of an ecosystem. However, most of the research conducted on grazer-grassland interactions only considered one or two herbivore groups of different body size. We are aware of only four studies that assessed how three or more herbivore groups of different body size interacted with the grassland ecosystem they inhabit. In these studies the investigations were restricted to the effects of herbivores i) on plant-animal interactions (two trophic levels) in one or several vegetation types only or ii) plant-animal-soil interactions in a single vegetation type only. Consequently, our understanding on the functioning of grazer-grassland interactions considering the combined effect of several herbivore groups on vegetation types of different productivity and across several trophic levels is still very limited. To assess a multitude of potential interactions in a grassland ecosystem we propose to set up an experimental field-design to determine single and combined effects of four herbivore groups of distinctively different body size and foraging behavior in three different vegetation types (nutrient-rich short-grass, nutrient-poor tall-grass, intermediate mixed-grass) on plant, root and microbial biomass and nutrient content (nitrogen and phosphorus) as well as on the composition of plant and microbial communities. We will investigate these effects after one and two growing seasons of herbivore exclusion, respectively. The herbivore groups will include large (>10kg; red deer and chamois), medium (0.5 to 10 kg; marmots), and small (10 to 500 g; small rodents) vertebrate as well as invertebrate (< 10g) herbivores. We manipulate the system by excluding the different herbivore groups using well-established and tested techniques. Choosing the Swiss National Park as study area allows us to exclude any disturbance by human activities.We expect large and medium vertebrate herbivores to predominantly graze in the nutrient-rich short-grass and intermediate mixed-grass vegetation, while small vertebrates and invertebrates mostly feed in the tall-grass, where protection from predators is higher. Upon exclusions of large and medium herbivores we, however, expect the two other groups to graze more intensively in the short- and mixed-grass as long as forage quality remains high. Therefore they partially, but not completely, take over the role the excluded large and medium herbivores had previously. Consequently, we expect that our exclusions will provoke the strongest effects on both above- and belowground properties in the short- and mixed-grass vegetation. More specifically, we expect plant biomass to in- and root/microbial biomass to decrease in both the short- and mixed-grass vegetation types when one or more herbivore groups are excluded. Simultaneously, these exclusions lead to a decrease in forage quality and a change in the microbial community composition. These expected changes will already be detectable after one season of exclusion, but more pronounced after the second season. We do not expect that the exclusions will have an effect on above-and belowground properties in the tall-grass. To our knowledge the proposed study will be among the first to examine how more than two herbivore groups of distinctively different body size affect plant, root and microbial biomass/nutrient content and composition in a grassland ecosystem composed of three distinctively different vegetation types. Consequently, our results will considerably facilitate and improve our understanding of i) how different herbivore groups interact with one another in different vegetation types and the ecosystem as a whole, and ii) how different vegetation types and the entire grassland respond to grazing by different groups of herbivores (top-down effects). By acquiring a better understanding of animal-animal, animal-plant, animal-soil and plant-soil interactions in grassland ecosystems, we will gain information on grassland ecosystem functioning, which will allow us to predict future changes in vegetation composition and its feedback on foraging pattern of herbivore communities.
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