Degree Name

Master of Science (MS)

Semester of Degree Completion

1990

Thesis Director

John E. Ebinger

Abstract

The present study included surveys of a four hectare section of Barkhausen Conservation Area and a two hectare forested section in the Sand Prairie-Scrub Oak Nature Preserve. This study examines the floristic composition and structure of these forests, and some of the ecological parameters that may be responsible for their existence. In this study, the number, size and species of all living and dead standing trees (above 10 cm dbh) were recorded for each quadrat. The relative dominance, relative density, importance value, average diameter, density in broad diameter classes and basal area were then calculated for each species. Nested circular plots were randomly located in the 25 m x 25 m quadrats in order to obtain seedling and sapling densities. Seedlings under 40 cm in height, seedlings over 40 cm in height and sapling were tallied in nested circular plots of 0.0001, 0.001, and 0.01 ha in size. Soils were tested for pH and soil texture using the Bouyoucos Hydrometer Method.

Barkhausen Conservation Area which was dominated by black oak (IV = 111.2), blackjack oak (IV = 61.5), and hickory spp. (IV = 22.0); and had a density (trees/ha) of 237.9 with a basal area of 16.3 (m2/ha). A total of 20 woody species were recorded in the woods of which 9 were canopy trees and 11 were understory trees, shrubs and vines. These results are also similar to the forest of the Sand Prairie-Scrub Oak Nature Preserve which were dominated by black oak (IV = 180.4), blackjack oak (IV = 15.1), and hickory spp. (IV = 4.2); and had a density (trees/ha) of 394.5 with a basal area of 20.3 (m2/ha). This area contained 12 woody species of which 5 were canopy species and 7 were understory trees, shrubs and vines. These closed forests seem to be fairly stable in composition, since the relatively shade-intolerant dominant species tend to reproduce themselves due to the lack of competition in extremely xeric conditions, and the periodic burns which keep the canopy open. The fact that black oak and black hickory have a large number of individuals in the lower diameter classes, and have sufficient seedling and saplings for future replacement of veteran trees, tends to support these findings. Barkhausen Conservation Area and the Sand Prairie-Scrub Oak Nature Preserve are typical examples of closed forest associated with sand dunes of the Illinois River Sand Area Section.

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