At least for NIPF-managed and industry-managed stands, the relationship between stand age and pulp mill distance, other things held constant, is positive throughout the observed range of the data. For NIPF-managed stands, each mile of road distance to the nearest pulp mill adds about one-sixth of one year. For industry, each mile adds one-third of one year.
By way of illustration, this means, ceteris paribus, at mean values of other variables, an NIPF stand is expected to be seven years older eighty road miles from its nearest pulp mill than a comparable one growing next to the pulp mill. An industry-managed stand located eighty road miles from its nearest pulp mill is expected to be 13.5 years older than a comparable stand located next to the pulp mill.
