the quoted effects of harvesting
on genetic structure and the associated impacts on production
and persistence are generally suppositions only, with no direct
confirmatory measurements. One opportunity for understanding
genetic-related impacts on NTFPs may come from building on
the growing literature of the effects of logging on timber trees,
although different harvesting methods, products, rates of growth
and reproductive biologies mean that the ability to make generalisations
is limited (see below). A number of timber species have
been hypothesised to undergo dysgenic selection based on only
inferior individuals not being logged, which thereby contribute disproportionately
to the seed crop for the establishment of subsequent
generations (Pennington et al., 1981). Reductions in
genetic diversity, and changes in timber tree stand structure and
density that change mating patterns, can lead to inbreeding
depression (Lowe et al., 2005).