Influence of land use intensity on the decomposition rate of dead mammals in conjunction with the biodiversity of the carcass associated insect fauna
In the project “NecroPig” we are studying the influence of land use intensity on the decomposition rate of dead mammals at landscape and local scales. In terrestrial ecosystems, decomposition rate of animal biomass is heavily dependent on the availability of decomposers and detritivores and on abiotic factors of a certain habitat. Therefore, the aim of this project is to understand how the habitat structure and land use intensity influences the decomposition and removal rate of dead mammals in conjunction with the biodiversity of the associated arthropod fauna at spatial scales. The results of our studies will create synergies across many projects, since decomposition of animal biomass strongly influences functional biodiversity above and below ground.
1. Land use intensity has an influence on the abundance and diversity of the cadaver associated insect fauna.
2. Different exploratories exhibit different habitats and abiotic conditions that in turn influence abundance and biodiversity of the carrion fauna and cadaver decomposition rate.
3. Soil nutrient flow depends on abundance and type of the respective carrion detritivores, as well as on the soil conditions and ultimately influences the production of plant biomass.
4. Land use intensity has an influence on the composition of microorganisms in soil and consequently on microbe-dependent odour bouquets of decomposing cadavers.
5. Generalist carrion insect species react on either a wider range of volatile organic compounds (VOCs) or core VOCs which are present during the whole decomposition period while specialists react on a closer spectrum of cadaveric VOCs or a specific bouquet of VOCs characteristic for a specific succession stage.
In August 2014, we exposed 75 piglet cadavers (Sus scrofa domestica) on 25 forest MIPs per exploratory for collection and determination of cadaver visiting insects (in cooperation with Dr. Frank Reckel, Dr. Jan Eric Grunwald, LKA München and Dr. Krzysztof Szpila, University of Torun, Poland)). We installed photo traps (9 VIPs per exploratory) for quantification of large scavenging vertebrates. Furthermore, we analyzed decomposition rate by measuring cadaver weight at specific intervals. For evaluation of cadaveric nutrient cycling, we determine abiotic soil parameters such as type, structure, pH, and humidity and perform isotopic analysis (in cooperation with Dr. Martin Werth, University of Ulm) of tissues of piglet cadavers, soil material beneath the carcass and tissue of blowfly maggots. Since insect detritivores are attracted by VOCs released by cadaver associated bacteria, fungi and other detritivores we sampled VOCs in the field (headspace sampling). Later we will chemically analyze these VOCs (GC-MS, in cooperation with Prof. Dr. Stefan Schulz, University of Braunschweig) at different stages of decomposition. For selected generalist and specialist beetle species with a function as detritivores, we will analyze the attractiveness of electrophysiological active VOCs in field and laboratory bioassays.
Sampling - General sampling procedure of material on a decomposing piglet carcass (bacteria, insects, volatiles, soil ...) according to a defined sampling scheme (days 0, 2, 4, 6, 9, 16 ,23, 30 post mortem).
Weight loss – weighing of the piglet cadavers to gain information about the speed of weight loss between differently managed forests.
Camera traps - The camera traps installed captured larger animal visitors (foxes, feral hogs, raccoons ...) that were attracted to the odor of decay.
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