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Primary succession

Madeline Mohrman
Conservation Biology class, BIO 345, Biology Department, DePauw University
Fall semester 2015

The Quarry Bottom in the DePauw Nature Park provides the opportunity to observe the process of primary succession.  The Quarry Bottom is a novel habitat that consists of distinct areas undergoing different stages of succession.  The northwest corner supports more and larger trees, perhaps because there is more soil, leaf litter, or shade in this area.  The goal of our project was to investigate why some areas support more advanced stages of succession than others. 

We set up 50 x 50 meter plots within five areas of the Quarry Bottom into five areas.  Within each plot, we chose 10 randomly selected points for data collection.  At each point, we measured soil depth, soil moisture levels, soil texture, number of trees, tree species, tree diameter, canopy cover, leaf litter cover, and ground cover. 

There was no difference in soil depth among the five plots.  The average soil depth across all plots was 5.4 cm.  Soil moisture levels, soil texture, ground cover, and number of trees varied significantly among the plots.  Plots 4 and 5 had the highest soil moisture levels, more soil, more trees, larger trees, more canopy cover, and more leaf litter than the other plots.  

Our results provide evidence of different stages of primary succession in the Quarry Bottom.  The variation in tree growth among the plots may be due to variation in the soil.  Plots 4 and 5 had higher soil moisture and more trees, suggesting a correlation between soil moisture and tree growth.  Differences in soil composition, soil organic matter content, and soil texture may also contribute to variation within the Quarry Bottom.  Future studies could investigate the effects of wind, sun intensity, and hot temperatures on plant growth.  We observed more tree growth closer to the quarry walls, perhaps because this area provides protection from wind, sun, and hot temperatures, as well as leaf litter input from the trees on the quarry rim.