about 1–2 times the height of the hedgerows (Nuberg, 1998),
were dominant over whole alleys. Similar results have been
reported from the semiarid tropics where a 74.2% reduction in
sorghum grain yield resulted from competition for moisture
with up to fourmeters high trees (Singh et al., 1989). But also in
this case, alleys had a width of only 10m. In the transition area
from hedgerows to crops, the negative competition effect can
prevail over microclimatic benefits. This was also confirmed by