Site Selection, Survey and Treatment Plan - Afforestation, Reforestation and Forest Restoration in Arid and Semi-arid Tropics - page 71

selection of species especially suited to survive in these soils. Most of these measures
are expensive operations and should be considered only for high value plantations
such as urban amenities.
In relatively flat, rocky planes with skeletal soils, small crescent-shaped structures
like saucers are built. These half-moon terraces are constructed in dry masonry and
lined inside with the soil collected in situ. The interior of the saucer is filled with
soil to form a soil bed of significant depth, say 30 cm. The terrace is located to fall
on a crevice in the underlying rock. A lithophytic plant is planted in the bed of the
terrace. Watering at monthly interval may be required.
In barren rocky areas totally devoid of soil, soil may be imported from nearby
fields. Soil is filled in cylindrical retaining structures made of stone masonry. The
plant, in a way, becomes potted in situ. Watering will have to be provided for, since
harvesting of rain water is not possible. The structure must be located on a crevice
in the base rock so that the plant roots may penetrate the rock with relative ease. The
seedlings planted must be tall, preferably 2 years old.
It is not possible to dig contour trench in areas with shallow soils. Contour ridges
are therefore constructed. In contour ridges the soil is scraped and formed into a bund
running on contour. Consolidated soil of the ridge provides an adequate base for seed
sowing. The ridge and furrow combination also effects in situ moisture conservation.
The spacing of ridges is much closer compared to the contour trenches, usually 2-5 m.
Extensive sowing of shrub and tree seeds eventually makes these ridges into
vegetative hedges, performing a long-term function of soil and moisture conservation.
Selection of proper species is an important part of a strategy to afforest skeletal
soils. Grass, shrub, and tree species with a shallow root system, tree and shrub
species that are lithophytic in nature, and drought resistant and hardy species which
can survive in nutrient deficient soils are the ones to be preferred. Silvopastoral
systems are a preferred model for afforesting such areas, since grasses need very
little depth of soil and provide a complete soil cover.
Extra care in form of watering and manuring may be required in plantations
of demanding species raised in skeletal soils. Point-to-point watering is done with
a schedule designed to work in tandem with the rainfall pattern. Use of organic
manure, especially the farmyard manure (FYM), should be considered. The soil
will get enriched in terms of organic matter within a few years of establishing the
plantation and will not need artificial manuring thereafter.

3.8.4.4 Afforesting Gullied and Ravined Lands

Gullied and ravined lands pose special problems in terms of steep slope, severe ero-
sion, calcareous soil surface, poor moisture retention, and extremely poor infiltration.
Nearly devoid of any organic matter, the soils have a poor till and are deficient in nu-
trients. Extremely complicated and interwoven topography makes it difficult to plan
a network of contour trenches and other similar structures to arrest runoff. Special
measures are also needed to check progress of erosion, especially at gully heads,
which keeps advancing each year, eating into fresh table land.