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    A statistical analysis was performed that identified time trends in the Scheffer Index value for 167 locations in the conterminous United States over the period 1969-2008. Year-to-year variation in Index values was found to be larger than year-to-year variation in most other weather parameters. Despite the substantial yearly variation, regression equations, with time (year) as the independent variable could be fit to the Scheffer Index data. A linear regression was found to provide appropriate fit when square-root transformations of Scheffer Index values were used as the dependent variable, and error terms were fitted as being spatially dependent. The 167 locations were segregated into ten climate groupings (termed “regions”) based on annual precipitation and number of Fahrenheit Heating Degree Days. In most “regions” the calculated time coefficient value for the regression equation was positive, indicating a 40-year trend toward increase in Scheffer Index value. In three of the ten “regions”, the time trend was moreover found to be statistically significant. All three of these “regions” were moist, with annual precipitation exceeding 20 inches (≈ 510 mm). The region with the most compelling increase in Index value was the moist region with in excess of 7000 Heating Degree Days. This region encompassed northern New England, the northern portion of the Great Lakes region, the Upper Mississippi valley, northern Minnesota, and the eastern part of North Dakota.

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    Lebow, Patricia K.; Carll, Charles G. 2010. Investigation of shift in decay hazard (Scheffer) index values over the period 1969-2008 in the conterminous United States. In: Proceedings, one hundred sixth annual meeting of the American Wood Protection Association, Savannah, GA; 2010 May 23-25: vol.106. Birmingham, AL: American Wood Protection Association, c2010: 118-125.


    Wood deterioration, climatology, biodegradation, climatic zones, wood biodegradation, weather, temperature, precipitation, regression analysis, equations, climatic changes, wood decay, climate index, decay resistance, wood decomposition, durability, statistical analysis, decay index, Scheffer index

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