Gradient Home


Recent News






Study Sites






Global Change Teacher Institute











































The Michigan Gradient Study: 


Long-term Data Sets


Long-term records of key variables along the climatic-pollutant gradient allow us to study ecosystem processes under real-world environmental conditions.  Some measurements have been continuously recorded since 1987, and in many instances, 16 to 18 years of data exist.  Data since 1994 contains values for both control and simulated NO3- deposition treatments. The long-term data base includes the following parameters:  forest productivity (basal area growth, height growth, biomass increment, individual tree vigor and mortality); soil and root respiration; wet deposition, soil solution chemistry, include NO3-, DOC and DON;  site water balance and solution leaching losses; soil and air temperature; soil moisture availability; above and below-ground litter inputs; seed production, leaf and fine root nutrient contents; leaf area index; insect defoliation; soil chemical and physical properties; leaf and root nitrate reductase activity; soil enzyme activity; microbial biomass and community composition; and N mineralization and nitrification.   Much of this data is available on-line through the links below.


Summary of years-of record for major data sets from the Michigan Gradient Study.   Red symbols indicate data exist for only a subset of the four study sites.



The links below provide data summaries for several of our important long-term data sets.  More detailed data than provided in the summaries as well as other data listed above can be obtained by making a formal request to Dr. Kurt Pregitzer (  All users of our data should properly acknowledge the source. 





Data Currently Available On-Line:


Growth and Productivity Data (basal area, basal area increment, biomass, biomass increment)


Litterfall and Foliage Data (foliar, woody and total litter mass, leaf litter N and C concentration, leaf litter SLA, stand LAI)


Climatic Data (air temperature, soil temperature, soil moisture, precipitation)


Site Water Balance  (monthly precipitation, temperature, AET, PET, moisture deficit and soil solution leaching flux)


Soil Solution Data (DOC, DON, NO3-, NH4+)


Soil respiration