Sh. Sharrow et al., PRODUCTIVITY OF 2 DOUGLAS FIR SUBCLOVER/SHEEP AGROFORESTS COMPARED TOPASTURE AND FOREST MONOCULTURES/, Agroforestry systems, 34(3), 1996, pp. 305-313
Resource sharing between tree and forage plant components in silvopast
oral systems includes a complex set of facilitative and competitive in
teractions. To the extent that facilitation exceeds competition, agrof
orests are expected to outyield monocultures of their components. Past
ure and Douglas fir (Pseudotsuga menziesii) tree production of young a
groforests was compared to pasture and forest monocultures under both
grid and cluster patterns of tree planting near Corvallis, Oregon, USA
, during 1983-1987, The height and diameter growth of forest and agrof
orest trees was similar, regardless of tree planting pattern. Five-yea
r average annual forage production was 6500, 5800, and 2800 kg ha(-1)
on pasture, agroforest, and forest plots, respectively. The total cumu
lative 1982-1987 above-ground phytomass yield of forage plus trees was
similar for pasture and conventional grid forest monocultures. The to
tal productivity of agroforests, however, was over 30% greater than ei
ther pasture or forest components grown in monoculture. Approximately
1.6 ha (0.96 ha forest + 0.64 ha pasture) of monocultures would be nee
ded to equal the productivity of 1 ha of agroforest.