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Size and growth patterns of trees in a maple-basswood forest restoration after twelve years.
Bartz, Traci1, DeChant, Timothy1, Shea, Kathleen*,1, 1 St. Olaf College, Northfield, MN
ABSTRACT- Growth patterns and survival of trees in a restored maple-basswood forest in southeastern MN, USA, were examined over a twelve year period. Data were collected on heights and diameters of 1,052 individually tagged trees planted in old fields. Tree size, growth curves, percent mortality and effects of plastic tree shelters were compared among species. Trees with tree shelters were significantly taller than trees without shelters after two years of treatment, but after eleven years there was no significant difference between trees with and without shelters. Tree mortality rates ranged from 9.9% in Acer rubrum, 17.6% in Tilia americana and 30.0% in Quercus macrocarpa to 50.7 % in Acer saccharum. The growth pattern of most species followed a linear increase in height over time, nearly doubling in height during the last three years. The mean heights of the tallest species, Quercus rubra, Fraxinus americana and Tilia americana, were 4-5 m while the shorter species, Juglans nigra and Acer saccharum, had mean heights from 2-3 m. Results suggest use of protective tree shelters is not recommended after the first three years unless herbivory levels are very high. Species with lower light tolerance, such as Acer saccharum, will become a more important component of the forest as trees reach reproductive age and the canopy closes over.
Key words: forest restoration, maple-basswood forest