Agriculture Reference
In-Depth Information
2.1.3
EFFECTS OF VEGETATION
A vegetation cover dampens the extremes of soil temperature variation on both a diurnal
and a seasonal basis; soils beneath a layer of vegetation are both cooler in summer and
warmer in winter. This is of considerable agricultural importance since extremes of
temperature are inimical to plant establishment and growth.
In the tropics‚ temperatures may become very high on unvegetated soil surfaces and
in the upper part of the solum immediately beneath. Unduly high temperatures will
reduce the germination and establishment of seedlings while low soil temperatures
frequently limit growth rates in cool climates. Further‚ high soil temperatures are
conducive to rapid organic matter oxidation and are thus undesirable from the viewpoint
of conserving this resource.
Soil temperatures are effectively reduced by the presence of a living canopy or a layer
of dead vegetation‚ either standing or as a surface mulch. This vegetation layer may
be a forest‚ a pasture canopy‚ chemically-killed standing vegetation or a superficial layer
of harvest residues or other organic materials. The effect of such a layer is to dampen
the extremes of soil temperature by intercepting part of the incoming radiation and
reducing convective exchange between the soil and the atmosphere.
Search WWH ::




Custom Search