cycling. This reached the stage of publication only from 1986 onwards, and
is partly due to two programmes which must rank as classics of agroforestry
research. These are the studies of hedgerow intercropping (called by its
originators, alley cropping or alley farming) at IITA, Ibadan, Nigeria; and
the set of studies of nutrient cycling under coffee/cacao with (so-called)
shade trees, conducted at or from CATIE, Turrialba, Costa Rica. Modification
of microclimate or the soil water balance by trees has received
surprisingly little attention, and scientists interested in this must turn for a
basis to the symposium proceedings, Meteorology and Agroforestrv [4].
Fruit production, including walnut and the so-called vegetable trees such
as peach palm and sago palm, is of continuing interest. So, too, is fodder
production, the 5 articles listed here being associated with the 22 on silvopastoral
systems. But whereas the layman thinks of fuelwood as possibly the
primary product from agroforestry, few scientists seem to have thought it
worth specific attention. The major source here is the two volumes of
Firewood Crops [2].
A number of scientists, among them the present writer, believe that roots
play a major role in the tree/crop interactions that lie at the heart of
agroforestry. There have only been three specific root studies, but these are
of high quality.