| Abstrakt: |
Changes in vegetation and land use since 1826 were evaluated along the 800 kilometer portion of the Missouri River flood-plain that extends across the State of Missouri using County Land Office Survey records for 1826 and aerial photos for 1937, 1958, and 1972. The combined results show a decline in flood-plain forest coverage from 76% in 1826 to 13% in 1972; cultivated land increased from 18% to 83% during the same time. Uncultivated-unforested areas increased from 6% in 1826 to 27% in 1937, then declined to 1% in 1972; these changes occurred coincident with extensive bank-stabilization and channelization activities initiated in 1912 by the U.S. Army Corps of Engineers. Riverbank stabilization activity since that time may account for the increased rate of decline in flood-plain forests from 0.25% per year between 1826 and 1937 to 1.6% per year between 1937 and 1972. The overall species composition of the 1826 flood-plain forests was found to be most similar to mature forest stands evaluated in 1972; similar frequencies in 1826 and 1972 occurred for hackberry ( Celtis occidentalis; 80% in 1826, 83% in 1972), elm ( Ulmus spp.; 80% and 83%), and sycamore ( Platanus occidentalis; 57% and 50%). Pawpaw ( Asimina triloba), found only in mature flood-plain forests in 1972, was recorded along 54% of the 1826 section lines. These combined data indicate (1) that pre-settlement flood-plain forests were extensive and included frequent, mature stands, (2) that in certain areas substantial portions of the flood-plain were in cultivation prior to extensive riverbank stabilization and channelization, and (3) that increased flood-plain forest clearing occurred coincident with increased bank-stabilization activities. [ABSTRACT FROM AUTHOR] |
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