COMPLEMENTARITY OF LIGHT AND WATER-USE IN TROPICAL AGROFORESTS - II -MODELED THEORETICAL TREE PRODUCTION AND POTENTIAL CROP YIELD IN ARID TO HUMID CLIMATES
Mgr. Cannell et al., COMPLEMENTARITY OF LIGHT AND WATER-USE IN TROPICAL AGROFORESTS - II -MODELED THEORETICAL TREE PRODUCTION AND POTENTIAL CROP YIELD IN ARID TO HUMID CLIMATES, Forest ecology and management, 102(2-3), 1998, pp. 275-282
A generic, process-based model [Mobbs, D.C., Cannell, M.G.R., Grout, N
.M.J., Lawson, G.L., Arah, J., Friend, A.D., 1997. Complementarity of
light and water use in tropical agroforests: I. Model outline, perform
ance and sensitivity. For. Ecol. Manage. 102, 275-282] was used to cal
culate 50-yr mean potential sorghum grain yields and overstory tree an
nual net primary productivities (NPP) in nine climates (with 348-2643
mm rainfall, ranging from Mall to southern Nigeria) with uniform overs
tory leaf area indices (LAIs) of zero to 1.5. It was concluded that in
regions with less than about 800 mm rainfall, simultaneous agroforest
ry may enable more light and water resources (current rainfall) to be
'captured' than sole cropping, giving complementarity of resource use.
However, owing to the low water use efficiency of (C3) trees at dry s
ites and the sensitivity of (C4) crop yield to shading, it may be diff
icult to increase total site productivity by growing trees with crops
in regions with less than 800 mm rainfall without jeopardising food se
curity-unless tree roots tap the water table, trees improve soil ferti
lity and/or they produce biomass of high value (fuel, gum, iodder, fru
its). (C) 1998 Elsevier Science B.V.