4. Discussion
Production data from both years suggest a net benefit of
intercropping with functionally diverse species in terms of both
overall productivity and per plant productivity. Intercropping
combinations incorporating three or four species (Wpwo and
Wpwoc) consistently overyielded, having the highest plot LER in
both years and per plant production values for watermelon, okra,
and peanut. A decline in plot LER was evident with the addition of
pepper (Wall). This suggested there may have been a threshold
where the benefits of intercropping with this particular combination
of species were maximized. It has been suggested that an
increase in functional group diversity has the greatest impact on an
ecosystem when few functional groups are represented to begin
with (Moonen and Barberi, 2008). The diminished positive effects
on a community resulting from an increase in species diversity
often occur with the introduction of functional redundancy
(Wohl et al., 2004). Thus, it is possible that pepper may have
had functionally redundant qualities that did not contribute to an
increase in the overall productivity of the system. A more likely
explanation for the observed decline in LER with the addition of
pepper is that pepper experienced very little intraspecific
competition in the monoculture given their relatively small plant
size while interspecies competition was much greater in the
intercropped combinations, particularly from watermelon and
okra due to their much larger plant size.