Linking Scavenging and Ecosystem Ecology

On Thursday, October 31 @ 11am ET, join Cary Institute for a virtual scientific seminar by Dr. Laurel Lynch, University of Idaho.

On the small Australian island-state of Tasmania, the progressive spread of a transmissible and highly lethal cancer threatens Tasmanian devils (Sarcophilus harrisii) with extinction. The resulting natural experiment—where devil population densities vary from 5% of carrying capacity in the east of Tasmania to 90% of carrying capacity in the west—offers a rare opportunity to test whether the decline of an apex scavenger can scale up to impact ecosystem processes.

Our team of community and ecosystem ecologists, evolutionary biologists, and forest scientists have spent the past several years exploring how devil declines impact scavenger foodwebs, carcass decomposition, soil biogeochemistry, and forest carbon sequestration. We found that carcasses in high devil-density areas were consumed far more rapidly and thoroughly than those in low devil-density areas, reducing nutrient flow belowground. In contrast, carcasses that were slowly consumed by a diverse scavenger network (e.g., mesopredators, avians, invertebrates), delivered up to 47 times more nitrogen and 11 times more phosphate to soils directly below the carcass, significantly altering microbial community composition and function.

Because devils concentrate carcass-derived elements in their scat, we next fused experimental data and modeling to test whether dispersed inputs could subsidize forest productivity. We found that devil scat inputs are likely to sustain, or increase, above and belowground net primary productivity and microbial biomass carbon through the year 2100. In contrast, replacing devil scat with lower-quality scat inputs (e.g., from non-bone-consuming scavengers and herbivores) caused forest carbon pools to increase more slowly, or decline, under expected increases in temperature and changes in precipitation. Because ecosystem processes are responsive to many drivers, our results in Tasmania highlight the importance of considering how multiple global change factors (e.g., biodiversity loss, biotic-abiotic feedback, climate change) scale up to impact current and future ecosystem function.

Free and open to all. Registration required via Eventbrite.

Host or Publisher Cary Institute of Ecosystem Studies