NOT ADDING UP: Three experimental ecosystems demonstrate the effects of herbivore (left), detritivore (middle), and combination (right) food chains on soil nitrogen levels (N). In the herbivore food chain, grasshoppers’ feces elevate nitrogen levels over those in a plant-only control ecosystem (not shown). In the detritivore and combination food chains, nitrogen levels are the same as the control, suggesting the food chains interact to dampen the nitrogen-elevating effects of the herbivores.PHEBE LI FOR THE SCIENTIST
The paper
R.W. Buchkowski, O.J. Schmitz, “Detritivores ameliorate the enhancing effect of plant-based trophic cascades on N cycling in an old-field system,” Biology Letters, doi:10.1098/rsbl.2014.1048, 2015.
Life on Earth may be carbon-based, but it wouldn’t exist without nitrogen. Soil microbes transform nitrogen from the air and from decaying organic matter into forms of the element available to plants and, in turn, the animals that eat them.
Within their respective food chains, detritivores—dirt-dwelling invertebrates that feed on decaying matter—and herbivores have been shown to raise soil nitrogen levels. And although it stands to reason that interactions between these food webs might act synergistically on nitrogen levels, it was unknown what their combined impact might be.
To examine this question, graduate student Robert Buchkowski and his advisor ...
