In recent history, deer populations have increased due to the near extinction of natural predators and an increase in available food from agriculture. We need to understand the impact that overabundant deer have on ecosystems in our Miami University Natural Areas. Deer browse causes damage to seedlings, and when seedlings are depleted few become saplings, understory, and canopy trees. This disruption can cause regeneration failure, where a healthy forest is at long-term risk due to the juvenile population lacking sufficient density, diversity, or composition to replace the current canopy.
Over the summer of 2022, I analyzed the severity of deer impacts by examining browse damage, density, species composition/richness, and size structure of trees. I studied forests in five Miami Natural Areas (Western Woods, Southern Bachelor Preserve, WRA, Bachelor Preserve East, Reinhart Preserve) and the Ecology Research Center, with four cameras along game trails at each. I counted images from the cameras containing deer as well as pellet counts along transects to quantify deer activity, which was used as a measure of relative density. Four transects were established at each site, and trees within 1m of transects were identified and measured. This allows us to analyze the composition and health of the forests in the MUNA.
I found that all the sites studied in the MUNA were experiencing some degree of regeneration failure. Many of the remaining seedlings were ash trees which will not make it to the canopy due to the Emerald Ash Borer, an invasive insect that results in Ash tree death. When removing ash trees from calculation, the degree of regeneration failure in the MUNA is even more drastic. The sites with the lowest seedling densities correlated to the sites with the most deer pellets, which aligns with our hypothesis that deer are causing regeneration failure in the MUNA.
Presenter(s): Elea Cooper, Biology Major
Advisor(s): David Gorchov, Department of Biology
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