iXfcW YORK 

 BOTANICAL 



TORRE Y A 



Vol. 26 No. 3 



May- June, 1926 



THE EFFFXT OF INUNDATION ABOVE A BEAVER 

 DAM UPON UPLAND VEGETATION 



Frank C. Gates* and Edith C. Woollett 



Late in August, 1924, a beaver dam was discovered in Carp 

 Creek, a small stream about 13 meters wide, flowing from the 

 Gorge — a prominent scenic feature in the region of Douglas 

 Lake, the location of the Biological Station of the University 

 of Michigan. The water flows from Douglas Lake via an under- 

 ground route and empties into the heads of the Gorge as cold, 

 (8-12° C), moderately swift flowing streamlets which soon unite 

 as Carp Creek. This stream is about 1.5 kilometers in length 

 and empties into Burt Lake. 



The dam as first seen was approximately 38 meters in length 

 and .1.3 meters above the bed of the stream. It empounded 

 water above it a distance of about 180 meters. Time did not 

 permit any special study of the eff^ects upon the vegetation, 

 beyond the general observations that the ground vegetation was 

 quite or entirely wiped out in the upland area covered by the 

 empounded water. Very many of the trees were dying. 



By June, 1925, considerable addition had been made to the 

 dam, so that it was now about 69 meters across. This raised 

 the level somewhat, making the empounded water run up stream 

 some 275 meters, furnishing a pond with an area of approxi- 

 mately 9700 square meters. The depth varied from a few 

 centimeters to a maximum of 2.2 meters in a place just above 

 the dam, from which the bottom material had been scooped to 

 plaster the dam. In June, 1925, a subsidiary dam was com- 

 menced about 30 meters downstream causing a new inundated 

 area in the woods. 



During 1925, the vegetation of the empounded area was 

 studied. This area had previously been streamside woods, 



* Contribution No. 249 from the Department of Botany & Plant Pathology, 

 Kansas State Agricultural College and a contribution from the Biological Station 

 of the University of Michigan. 



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