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Harvard Forest REU Symposium Abstract 2018
- Title: An Analysis of Tree Competition within Harvard Forest and its Effects on Growth and Mortality
- Author: Laura K Puckett (Virginia Polytechnic Institute and State University)
- Abstract:
It is known that competition between trees for sunlight and resources negatively affects their growth and can even lead to mortality. Most competition studies have either compared plot-level competition with growth over multiple years or the competition experienced by individual trees in a single growing season. Few studies have compared competition with growth and mortality of individual trees over multiple years. This study compares competition, growth, and mortality over ten years for eight permanent Harvard Forest plots associated with the EMS flux tower. An existing dataset of seasonal diameter at breast height (DBH) for each tree greater than 10 cm DBH was used, and the tree locations were mapped. Multiple competition indices based on DBH and distance between trees were computed for each tree at a yearly interval. The competition indices were analyzed in combination with annual DBH growth increment for each tree. A t-test showed significant differences between the mean competition index of alive trees and trees that eventually died. The linear regressions of annual growth increment as a function of competition index for each individual were negatively correlated, with an average coefficient of correlation between 0 and 0.4 for each species studied. This relatively small effect may indicate that the competition indices used are not sufficient to describe tree competition, or that the effect of competition on tree growth and survival is less influential than other factors. These results increase the understanding of background mortality near the EMS tower, which is an important factor in interpreting forest dynamics.
- Research Category: Large Experiments and Permanent Plot Studies; Physiological Ecology, Population Dynamics, and Species Interactions
