Twenty-Six Years of Change in a Pinus strobus, Acer saccharum Forest, Lake Itasca, Minnesota

Abstract

PEET, R. K. (Dept. Biol., Univ. N. Carolina, Chapel Hill, NC 27514). Twenty-six years of change in a Pinus strobus, Acer saccharum forest, Lake Itasca, Minnesota. Bull. Torrey Bot. Club 111: 61-68. 1984.-A 0.48 ha permanent plot located in a mesic Pinus strobus dominated forest was remapped after 26 years. Pinus remained the dominant species in basal area and had the lowest mortality rate of any major tree species. The understory was dominated by Acer saccharum, Tilia americana, and Ostrya virginiana, all of which had high mortality rates. Establishment of numerous new stems resulted in a net gain in Ostrya and Tilia density whereas Acer declined substantially. Populations of the shade intolerant Populus tremuloides, P. grandidentata, and Betula papyrifera, which appear to have become established following mild surface fires in the late 1800's, all had high mortality. The shiort-term prognosis is a stable Pinus strobus canopy, loss of Populus and Betula, and a steady enrichment of the understory with Ostrya and Tilia. Acer should remain important but continue to decline in relative density. The long-term outlook is uncertain owing to the increasing probability of catastrophic breakup of the pine canopy.