Ecosystem parameters can be classified as “site specific” (varying among sites but not among years), “year specific’ (varying among years but not among sites) or “stochastic” or “mixed” (varying among sites and years). The classification allows inferences about factors controlling each parameter. Site specific parameters are influenced by factors intrinsic to each site; year specific parameters by conditions in a particular year, e.g. weather; and stochastic or mixed parameters by a complex interaction among site and year specific parameters. We are demonstrating the utility of this approach with 11 years of Birge-and-Juday zooplankton data on 5 lakes and analyses of our first 5- years of LTER data on a wide variety of hydrologic, geologic, and biologic variables, considering each of our 7 lakes as a site. The indices of spatial and temporal variation are not ecosystem specific and we believe they can be extended to form a new basis for intersite analyses and comparisons among aquatic and terrestrial ecosystems.
Primary production measurements on Crystal, Little Rock, Sparkling, and Trout Lakes are available since 1985 for comparative intersite analyses. We are using C-14 and laboratory incubation methods to generate daily and annual production of the entire water columns.
Groundwater input to a lake’s hydrologic budget strongly influences the response of the lake to atmospheric deposition. Anderson and Bowser (1986, Water Resources Research 22:1101-1108) estimate significant time lags in lake acidification dependent on the extent that precipitation mixes with the groundwater before entering the lake and on the weathering reactions that occur in the groundwater.
Carl Bowser is on sabbatical working with Tom Winter at the USGS In Denver this year: Dave Armstrong has taken on his LTER responsibilities for the year. Tim Allen has joined our core of Wisconsin faculty committed to the LTER program and is interested in applying hierarchy theory to site and intersite analyses.