Patterns of sycamore growth at four locations surrounding an abandoned limestone quarry
David Pope, Science Research Fellow
in collaboration with Bryan Helm, Aaron Randolph, Dana Dudle, and Vanessa Fox
We measured the effect of location on growth patterns of sycamore trees (Platanus occidentalis) in and around an abandoned limestone quarry (quarry, rim trail, river trail, meadow). Sycamore trees have been documented as growing in quarries, strip-mined lands, and other stressful areas for years. We wanted to determine the effect these stressful growing conditions might have on the trees. We predicted that trees located in the quarry would grow slower, have lower limbs, and not reach the same sizes as trees in the other locations.
We sampled trees from the four different locations along transects. Total height, diameter at breast height (dbh), and lowest live limb height were recorded for each tree. The ages were estimated for a group of trees from each location. ANOVA, ANCOVA, and chi-square analysis were used to determine if significant statistical differences were present.
Results reflected a complex mixture of variables affecting the way trees grow. Trees at the rim trail and quarry were growing at a similar rate, and trees at the river trail and in the meadow also were growing at a similar rate. Trees were smaller with lower limbs on average at the quarry and meadow than at the rim and river trails. Consistent growth rates possibly indicate similar levels of stress in the quarry and on the rim trail, and similar levels of stress in the meadow and on the river trail. The data support the hypothesis that the trees in the meadow are younger than the trees in the quarry, while the trees on the two trails are the oldest due to longest time since their last disturbance. The lowest live limb data makes sense when considering the greater levels of competition for sunlight on the rim and river trails than at the quarry or meadow .
We have determined what is going on in the sycamore populations at the quarry, the next step is to determine why. Some ideas about future studies are: spatial analysis of sycamores and their growing areas, determining water and nutrient availability in the soil, and to learn the exact history of land use at the quarry and the surrounding areas.