The forest soil data set contains measurements on 58 soil
pits in the Hubbard Brook Experimental Forest in north-central
New Hampshire. The excavations were done in 1983 and 1986. The
soil samples were analyzed for the exchangeable cations of
aluminium, calcium, magnesium, potassium and sodium. The pit
locations in both data sets can be classified by the
type of the forest:
1: spruce-fir (11 samples),
2: high elevation hardwood (23 samples) and
3: low elevation hardwood (24 samples)).
Additionally the degree of logging disturbance can be considered
(all 0 in the 1983 data set):
The observations are expressed in grams of exchangeable
cations per square meter.