3.1. Minimizing fragmentation
Landscape fragmentation, i.e. the breakup of large areas into
smaller parcels must be evaluated and controlled because it influences
many ecological processes (see e.g., Barrett and Peles, 1994).
It can be measured by multiple indicators (see e.g., Hargis et al.,
1998; McAlpine and Eyre, 2002; Öhman and Lämas, 2005). Here,
we consider as examples two common indicators, the mean nearest
neighbor distance (MNND) and the mean proximity index (MPI),
which estimate the relative isolation of the parcels. These indicators
are among those that are used in FRAGSTATS (McGarigal and
Marks, 1994), software well known in landscape ecology. Optimization
problems associated with the notion of fragmentation include,
for example, the selection of a subset of parcels optimal
for these indicators. The selected parcels will be, for example, pr