Dipl. Biol. Roswitha Ehnes

For my PhD as a part of the biodiversity exploratories, I am working on respiration rates of soil invertebrates and on effects of forest types on soil communities. For the first part of my thesis, I set up a database on respiration of invertebrates both with literature data and own measurements of oxygen consumption which I then analyzed for several metabolic theories. Furthermore, I calculated the different parameters of the linear model of respiration equation based on metabolic theory of ecology (Brown et al. 2004) and modified by Downs et al. 2008, so the values of the allometric exponent, a, and the activation energy, E, are not fixed:
I=i₀*M_a*e ^(-E/kT)



The resulting superior fit of the phylogenetic model (accounting for differences in allometric exponents, activation energies and normalisation constants between phylogenetic groups) demonstrated that differences in physiology, ecology and body architecture of invertebrates translate into differences in the scaling of metabolic rates. Thus, including phylogenetic group is important in a model to predict metabolic rates of different phylogenetic groups accurately (Ehnes et al. 2011).



In a second project, I want to use the parameters for the respiration of soil invertebrate taxa to calculate the amount of energy the different populations use in different forest types. This is a cooperation project with the group of Stefan Scheu, where we took soil samples in 2008 in all three biodiversity exploratories in differently aged beech forests. The soil fauna was extracted, counted and determined to species level.
With the parameters from the respiration data I am able to calculate the respiration of a population of a certain species. My aim is to find out if the energetic equivalence rule holds, which predicts that abundance-mass slope and respiration-mass slope cancel, resulting in an population energy use independent of the body mass of the various species.




Publications

2014

Klarner B., Ehnes R. B., Erdmann G., Eitzinger B., Pollierer M. M., Maraun M., Scheu S. (2014): Trophic shift of soil animal species with forest type as indicated by stable isotope analysis. Oikos, 123: 1173-1181.

Ehnes R. B., Pollierer M. M., Erdmann G., Klarner B., Eitzinger B., Digel C., Ott D., Maraun M., Scheu S., Brose U. (2014): Lack of energetic equivalence in forest soil invertebrates . Ecology, 95(2): 527-537.

2011
Ehnes R. B., Rall B. C., Brose U.: Phylogenetic grouping, curvature and metabolic scaling in terrestrial invertebrates. Ecology Letters, 14(10): 993-1000.

Vucic-Pestic O., Ehnes R. B., Rall B. C., Brose, U.: Warming up the system: higher predator feeding rates but lower energetic efficiencies. Global Change Biology, 17(3): 1301-1310.


2010
Rall B. C., Vucic-Pestic O., Ehnes R. B., Emmerson, M., Brose, U.: Temperature, predator-prey interaction strength and population stability. Global Change Biology, 16(8): 2145-2157.


2008
Brose U., Ehnes R. B., Rall B. C., Vucic-Pestic, O., Berlow, E.L., Scheu, S.: Foraging theory predicts predator-prey energy fluxes. Journal of Animal Ecology, 77(5): 1072-1078.

Conference contributions

Ehnes, R.B, Brose, U. (2011): Abundance and population-energy use in forest-soil communities. - Oral presentation at the British Ecological Society Annual Meeting, Sheffield University

Ehnes, R.B, Brose, U. (2011): Abundance and population-energy use in forest-soil communities. - Oral presentation at the 41st Annual Meeting of the Ecological Society of Germany, Austria and Switzerland, Oldenburg University

Ehnes, R.B, Brose, U. (2010): No energetic equivalence in forest soil food webs. - Poster presentation at the British Ecological Society Annual Meeting, Leeds University

Ehnes, R.B, Brose, U. (2010): Lack of energetic equivalence in forest soil food webs. - Oral presentation at the 40th Annual Meeting of the Ecological Society of Germany, Austria and Switzerland, Giessen University

Ehnes, R.B (2010): Energetic equivalence in forest soil food webs. - Poster presentation at the Multitrophic Interactions Workshop, Göttingen University

Awards

2010 Best Poster Award, British Ecological Society (BES)
Ehnes, R.B, Brose, U.: No energetic equivalence in forest soil food webs.