Graduate Program

Environmental Biology

Degree Name

Master of Science (MS)

Semester of Degree Completion

1989

Thesis Director

John E. Ebinger

Abstract

During the fall of 1988 and the spring of 1989, four stands of river birch (Betula nigra L.) were surveyed in Cass and Mason Counties, Illinois. All study areas were divided into quadrats 25 m on a side (0.154 acres) and the maximum number of quadrats were placed to completely survey each forest. The relative density, relative dominance, and importance value was calculated for each species (dbh greater than 10 cm) in each forest area. Also, seedlings (less than 2.5 cm dbh) and saplings (2.5-10.0 cm dbh) were recorded in each area. River birch is the dominant overstory species in each of the study areas accounting for 83% to 92% of the basal area (sq m/ha) and 75% to 87% of the overstory individuals in the woodlots. The dominant understory species at Site B are black oak, black cherry, and black hickory. At Site C, silver maple and American elm are the dominant understory species. Green ash is the dominant understory species at Site D. There are few common understory species at Site A. River birch will continue to dominate the overstory in these wet, acidic, and sandy woodlots for the near future. However, river birch dominance in the overstory is preventing river birch seedlings and saplings from maturing, since this species is intolerant of shade. Therefore, other species, such as silver maple and green ash, may increase in importance, resulting in a change in the future composition of these river birch forests.

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