Print PageMuch of the maple-basswood forest type, endemic to south-central Minnesota USA, has been fragmented and degraded due to recent human activity such as logging, agriculture, and development. Data on growth and survival patterns have been collected on over 1,000 trees in a maple-basswood forest restoration project started in 1990 on former agricultural fields at St. Olaf College, Northfield, Minnesota. The overall goals of the project were to better understand patterns of young tree growth and increase the effectiveness of forest restoration projects. Our specific goals were to 1) track patterns of tree growth and mortality over time, 2) determine how soil characteristics change over time and 3) make projections about future changes in the forest based on mortality, tree reproduction and seedling recruitment.
Results/Conclusions
As the trees have matured over 20 years, tree sizes have diverged and each tree species has had differential success. Red oak and American basswood had the largest mean diameter while ironwood and sugar maple had the smallest. Overall mortality was 33.66%, but varied greatly between species from 0 to 60 percent with species like sugar maple having very high mortality (55%) while American basswood had low mortality (18%). Soil characteristics such as % organic matter, % moisture, and PO4-P content were significantly lower in the restored forest areas than in a nearby mature forest, but have been increasing over time. Only a handful of species, including northern red oak and American basswood have produced seeds while a much wider variety of seedlings have been recruited from a neighboring forest. Implications for management included data showing tree tube protectors have no long-term benefits for growth and planting grass decreased seedling recruitment. In conclusion restored forest soil characteristics have been changing to become more similar to a nearby mature forest, and we expect that this pattern will continue in the future. In areas where the canopy has closed over the forest is approaching a mature maple-basswood forest.
