Presettlement forest types in Iowa

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Dick-Peddie, William
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A study of the primeval forest cover was made of three Iowa counties, Allamakee, Jackson and Lee, three belt transects across the state east-west and a number of townships on the Des Moines and Missouri Rivers, using the original land survey notes of witness and on-line trees;A total of 15,291 trees was recorded and described by surveyors from the three counties, the three transects and the river townships. Thirty-six genera and species were recorded, with the smallest number in the northern county and transect and the largest number in the southern. Quercus spp. made up about 67 percent of all the trees recorded;The average diameters of the trees in the counties comprising at least 2 percent of the total, with the exception of Ulmus spp., were found to increase from north to south;Quercus macrocarpa was found to be the dominant species near the prairie-forest ecotone. It was also found to have a smaller average diameter and a larger average distance away from the corner than Quercus alba and Quercus velutina, indicating oak-barrens vegetation and recent or current invasion;The primeval forest cover in the areas studied appeared to be scattered, except for the oak-maple-linden communities, and to be evenly divided by rivers and streams. This uniform distribution suggests little effect of wind-sorted outwash (19) or fire (9, 10, 11) on forest distribution in these areas;The mean diameters of the witness trees recorded in the transects also showed a decrease to the north. The percentage of trees falling on line decreased sharply to the north in the transects;There was found to be a definite decrease in a westerly direction of both mean diameters of the trees and percentage of trees falling on line;The number of tree species appears to have increased since the original survey from a comparison of two studies made on the timber of the Des Moines and Missouri River valleys;The forest-soil relationships indicate that the forest was advancing over prairie soils 100 years ago in the areas studied.

Sat Jan 01 00:00:00 UTC 1955