Yield measurements in linear agroforestry systems such as boundary
plantings, live fences and shelterbelts (Fig. 6) follow the same principles
outlined earlier with hedgerow intercropping, particularly as applicable to
wide-spaced hedges. For both hedgerow intercrop and upperstorey trees in
cropland, sampling can be considerably simplified if the spacing is regular. In
Fig. 7, each sample area contains crop in each stratum in the same proportion
as in the whole unit. Hence we can measure the total yield from the
sampled area and divide by its area. No further weighting is necessary. Such
a sampling scheme is described as 'self-weighting'.