Trophic cascade alters ecosystem carbon exchange

The scientific report ‘Trophic cascade alters ecosystem carbon exchange’ by Strickland et al. (2013) explores the possible effects of trophic cascades on the carbon cycle. 

The effects of cascades on biogeochemical cycles are largely unexplored. “We’re discovering that predators are having important effects on shaping the make-up of ecosystems,” says Dr. Oswald Schmitz (2013), “but we’ve not really spent a lot of time measuring how that translates into other functions like nutrient cycling and recycling.” 

The experiment tested whether predator and herbivore abundance and their effect on the abundance and physiology of plants, influenced carbon dynamics in plants – carbon storage, fixation and allocation. In a meadow ecosystem a spider (Pisaurina mira) and a grasshopper (Melanoplus femurrubrum) were the carnivore and herbivore species. 

Predators have a huge effect on carbon cycle (Schmitz 2013)

Strickland et al. (2013) hypothesised that 'carnivores should increase plant community carbon fixation and reduce respiration, thereby increasing carbon retention by causing herbivores to reduce their foraging impacts on plants’. The experiment showed that carnivores indeed increased carbon fixation and reduced carbon loss via respiration by plants. Thus the report accepted the hypothesis, concluding that trophic cascades do influence carbon dynamics in terrestrial ecosystems; the presence of carnivores result in the increase of carbon retention in plants. “It’s going to force some thinking about the vital roles of animals in regulating carbon,” concludes Dr. Schmitz (2013), pointing to the fact the UN’s body of scientific experts who study climate change don’t consider these multiplier effects in their models. “People are arguing for a paradigm change.”

Trophic cascades affect so many different aspects of ecosystems. I constantly wonder at the delicate balance in nature but am also impressed by the flexibility of ecosystems to adapt when the equilibrium is disturbed - though this flexibility is not limitless. 

References

Schmitz, O.J 2013, ‘Study shows dramatic effects of predators on carbon cycle’, RedOrbit, <http://www.redorbit.com/news/science/1112876639/effects-of-predators-on-carbon-cycle-061813/ >

Strickland, M.S, Hawlena, D, Reese, A, Bradford, M.A & Schmitz, O.J 2013, ‘Trophic cascade alters ecosystem carbon exchange’, pnas, vol.110, no.27, pp. 11035-11038.