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Harvard Forest REU Symposium Abstract 2011
- Title: Red Maple Growth Rate Responds to Environment, Not Competition
- Author: Collette G Yee (College of San Mateo)
- Abstract:
The understory dominant red maple (Acer rubrum) is one of the most common trees in eastern North America and grows well across a wide range of site conditions. While some studies suggest an increase in its canopy importance over time, other conflicting evidence displays unchanging canopy dominance. Using a permanent forest plot that spans environmental gradients, we studied the influence of site, disturbance and biotic factors on the growth rates of A. rubrum over time. Growth patterns of 2492 red maples were analyzed from the Lyford Grid, a 3 hectare permanent plot censused in 1969, 1975, 1991, 2001 and 2011. For every tree ≥5cm diameter at breast height, its size, condition and location within the canopy were recorded at each census. Mapped data displaying the types of soil moisture and levels of damage from the 1938 hurricane was used to assign environmental conditions for each individual tree. At each census interval, we tested how growth rates of A. rubrum varied with differing soil moisture (ranging from dry to wet), 1938 hurricane damage (low, moderate, severe), neighborhood competition and initial diameter. The average annual growth for all A. rubrum continuously declined until the last census period between 2001 and 2011. Trees in the most saturated soils grew more than twice as much as individuals located on the driest areas of the plot. Areas that were severely damaged by the hurricane supported faster growth during the first three decades of the survey. Competition did not strongly affect annual growth rates. Initial diameter also had a modest but positive influence on the growth rate. Over the last 42 years, A. rubrum was the most numerous species in this forest, although it has steeply declined in percent composition after 1991. Overall, A. rubrum showed its characteristic flexibility by growing moderately across a wide range of environmental and competitive conditions.
- Research Category: Large Experiments and Permanent Plot Studies
