439 
Fig. 5 Farmland 1950 (left) & 1972 (right) ; 
one dot = 2 ha. 
distribution and their effects can be studied. As 
Chisholm (1979) pi40 says "Any technical change 
creates conditions of disequilibrium which may 
be of long or short duration according as the 
innovation in question is or is not major, and 
also according to the nature of the adjustment 
mechanism". One technical change that certainly 
started to occur between the chose dates is the 
increase in accessibility of most areas due to 
better roads and the introduction of small 
vehicles. These show up in the correlation between 
the proportion of woodland in a particular area 
and its distance from its potential consumers, 
mainly in Kaduna. Accessibility correlates in a 
strong negative way with the percentage of 
woodland in 1972, while in 1950 the relationship 
was in the opposite sense. 
10.2 Farmland, as would be expected, is more 
plentiful near to a road or a railway station, 
significantly correlated in 1972, less so in 1950. 
Other factors are at work here. As with respect 
to Kaduna, the correlation is significantly high 
in both years with time. This shows that 
topographical and soil factors in the S.E. of the 
test area may restrict farming activities. 
11. CONCLUSION 
Using sample from aerial photographs and dot grids 
it is possible to estimate land use changes in 
savannah areas with acceptable precision. 
Studies of this nature could provide a useful 
inexpensive way of obtaining land resources 
information in developing countries.