Large mammal decomposition effects on prairie communities

Background/Question/Methods

When a large animal dies and decomposes, there is large local disturbance and nutrient pulse in the immediate vicinity of carcass. With the human-caused reduction in native large mammals and/or livestock practice of removal of animals for harvest, the natural death and decay process has presumably been modified. In prairies where large mammals are most abundant, the loss of natural death and decay cycles may be a major factor affecting ecosystem function. We studied this phenomenon by placing road-killed deer to decompose in a natural Arkansas prairie and compared the plant community to areas not disturbed by this event. Here, we report the results of the first year of the experiment, which corresponds to the immediate disturbance event and short-term (one growing season) plant response.

Results/Conclusions

As expected, the disturbance and rapid decomposition caused plant mortality, but the effect was concentrated in grasses, which declined about 50% by the end of the growing season. However, forb percent cover, although showing a short-term decline immediately after deer decomposition, returned to its previous abundance by the end of the growing season. Grasses are typically competitively dominant in this system, so deer decomposition disturbance events may temporarily shift the environmental favorability to benefit the less dominant forbs. This process may in part explain the high species richness of herbaceous plants in prairies.