Publication Date


Document Type


First Advisor

Messenger, A. Steven

Degree Name

M.S. (Master of Science)

Legacy Department

Department of Geography


Soils--Boron content


Scores of red oak (Quercus rubra) and white oak (Quercus alba) trees exhibited a sudden decline and die-off beginning in 1972 at the Morton Arboretum. The decline was not attributable to insects or disease, but many of these trees were near wet, depressional prairie soils (Mollisols). Foliar samples taken from trees near these Mollisols showed significantly higher levels of the nutrient boron when compared to nearby trees on well-drained sites. The current study investigated the concentrations of boron in wet, depressional Mollisols compared to better drained soils upslope, and the potential of these soils to supply phytotoxic levels of boron. Three study sites were chosen at the Morton Arboretum based upon topography and locations of oak decline. Five transects were set up at each study site along a topo- sequence from a ridgetop to a bottomland. Soil samples were taken along each transect, analyzed for available boron, and statistically compared among topographic positions. Soil boron values at various slope positions were often significantly different and generally increased downslope. The base of the slope had the highest concentrations and the ridgetop and upper mid-slope had the lowest overall. Generally, soil boron values on the lower three slope positions were potentially toxic to sensitive plants.


Bibliography: I.73-77


vii, 77 pages




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