The effects of harvesting on long-term productivity
by means of management impact evaluafion studies
through modeling have attracted little attention until
recently (Kimmins, 1977, 1986; Dyck et al., 1986). If
the export of nutrients (mainly base cations, phosphorus
and micro nutrients) via harvesting exceeds deposition
and inputs from weathering of minerals, the
deviation of the nutrient balance from the steady-state
will indicate that the ecological carrying capacity has
been exceeded. Thus, sustainability is lost and stability
decreasesI.n many acid forest ecosystemsi n Europe,
harvesting may remove more base cations than are
replaced by mineral weathering. According to Ulrich
( 1987, 1991)) the existence of these systems is mainly
due to atmospheric inputs from pollution and they are
highly unstable.