Long term ecological research on Wisconsin lakes affected by human activities
The North Temperate Lakes, Long Term Ecological Research Project (NTL-LTER) has been conducted by the University of Wisconsin (UW) Center for Limnology since 1981. Research has focused on seven lake systems in the Northern Highland Lake District in northern Wisconsin, a state in America’s upper mid-west. Beginning in 1995, the project was expanded to include four lakes in southern Wisconsin near Madison, the state capital (Magnuson et al. 1997). The Northern Highland Lake District is a forested area containing more than 2500 Jake situated on approximately 40 m of sandy tills overlying granitic bedrock (Kratz et al 1997). Tourism is important. The lakes generally have low alkalinity and include oligotrophic, mesotrophic, and dystrophic types. The importance of the position of lakes within the regional groundwater flow syste and the temporal coherence of lakes have been areas of research emphasis (Magnuson et al. 1990; Kratz et al. 1997, 1998; Webster et al 1997). The southern NTL-LTER lakes are in a rich agricultural region that is rapidly urbanizing. The lakes are calcareous and exhibit eutrophic symptoms such as excessive algal blooms and/or dense growths of macrophtyes. One of the lakes is a seepage lake, while the other three lakes including Lake Mendota are drainage lakes with large agricultural and/or urban watersheds. Lake Mendota with the UW-Madison campus on the lake’s southern shoreline has the longest limnological record of any lake in North America. The lake was the site of a recent biomanipulation project where piscivores were heavily stocked to control algal densities (Kitchell 1992). LTER research on the northern lakes has emphasized landscape position factors that affect lake ecosystem dynamics. LTER research on the southern lakes has emphasized the land-water interactions particularly as impacted by human activities. However, both the northern arid southern lakes have experienced major impacts from human activities. A brief outline of those impacts are reviewed in Table I. Some of the impacts are unique to the northern and southern regions. Other impacts are more universal.
Madralin (near Warsaw), Poland