Agriculture Reference
In-Depth Information
development has been characterised by the frequent presence of excess water and which
is commonly saturated. At the lowest site‚ a gallery forest lines the bank of a stream.
The soil moisture data are partitioned into three matric potential ranges (> -0.03 MPa‚
-0.03 to -1.5 MPa‚ < -1.5 MPa) corresponding to saturation‚ “plant-available” water and
water held at potentials below an arbitrarily-designated “wilting point”.
From the figure‚ the effects of topography and vegetation are clear. Sites become
wetter for longer periods with progression downslope. While all sites were saturated for
considerable periods during the wetter months‚ the surface (0-10 cm) of the hydric
savanna soil was saturated for 230 days during 1969‚ a dry year for the area. In contrast‚
the surface layer of the plateau soil was only saturated for 130 days. In the gallery
forest‚ the surface soil was saturated for just 119 days during the same year‚ illustrating
the substantially larger water usage of the rainforest canopy and the higher rates of
internal drainage in this soil.
