We also restrict our consideration to three production categories:
non-timber forest product harvesting (from natural,
incipiently- and/or semi-domesticated forests and woodlands);
agroforestry tree products (AFTPs) and services (provided by a
wide range of mostly semi-domesticated local and exotic trees in
smallholder-farm landscapes); and woody perennial commodity
crops (which are often completely domesticated, exotic in major
production centres, and grown in both smallholdings and larger
plantations, though our concern here is only with the former).
The boundaries between these production categories are not
always easy to define, as evidenced, for example, by often subtle transitions in landscapes between forests and agroforests in a gradient of transformation and intensification
.In fact, one category often depends upon another for supporting sustainability, as, for example, many AFTPs and tree commodity crops were once NTFPs, and often also still are
(thus, the continued improvement of AFTP and tree commodity
crop production may depend to a greater or lesser degree on
accessing genetic resources maintained in natural stands;
.
Our three production categories have received considerable
attention for their roles in meeting development targets for
small-scale harvesters and smallholder farmers in the tropics, both of which groups are the subject of our attention here