Historical Changes in Abundance of Floating-Leaf and Emergent Vegetation in Minnesota Lakes

摘要

Whole-lake vegetation abundance of dense floating-leaf and emergent vegetation was estimated periodically for 100 north central Minnesota lakes from 1939 to 2003 to assess the consequences of shoreline development. Lakes were randomly selected from three shore land development classifications, which define Minnesota statewide minimum shoreline development standards. The classes, with increasing restrictions and higher standards for development, are general development, recreational development, and natural environment. Image analysis techniques were used to estimate vegetation abundance (% cover) from aerial photographs. Shoreline development varied by shore land development class. Floating-leaf and emergent vegetative cover (% of lake surface) was significantly affected by development. Increases in shoreline development, indexed by dock sites per kilometer, reduced plant cover.