The method used in the earliest collections at the HBEF by Gosz et al.
Federer's method differs from that of Siccama in the HBEF study.
The sampling methods at the HBEF were the most intensive of our three studies, involving from 52 to 87 blocks, each 15 X 15 cm, at each sampling date.
Results from the intensively sampled stand at the HBEF were consistent with the stands of similar age in the chronosequence: decreases in concentrations of Ca were more pronounced than were the changes in contents.
A different danger in experimental design is illustrated by our early comparison of two sample collections at the HBEF Studies of change in soils over time are often based on only two points in time (Johnson et al.
Calcium concentrations in precipitation at HBEF decreased fairly steadily from 1965 through 1983, and then increased slightly from 1983 through the early 1990s (Likens et al.
For mid-elevation (420-700 m) hardwood forests, we constrained total forest-floor mass at HBEF
at age 57 to match the value measured by Covington (1981), which was representative of forest-floor mass measurements in a 200-yr chronosequence (Covington 1981, Federer 1984).