Desertification of critical land in semi-arid zones is one of the main problems faced by farmers and highly affects socio economic impact.
Desertification in critical areas in semi-arid regions are often result of use, overuse and sometime abuse of a parcel. The increasing population pressure and increased resources and expectation has led to desertification in several areas, not everywhere aridity has played a pivotal role. In critical arid desert areas in Kuwait we have seen just fencing and over grasing has significantly increased vegetation, without any irrigation. But steps have to be taken before it is too late.
A collection of the sequence of events that produced desertification near unperturbed boundaries is indeed the first step to be put in evidence. Spots that are less dry than the mean would indicate a cause and solution if any, and a specific case study is required. Both water input and land use can concur. Water keeping strategies include watershed control, dams and control of irrigation. Overgrazing and annual crops like mais or cotton often occur at the place of natural vegetation. Trees improve soil permeability and increase shade but often are cut as wood fires or fuel. At end a strategy for mainteinance requires some chess board land planning in which would be possible to keep free parcels for restoring. People should know about the value of water and the governement produce commonal policies for keeping villages income.
Desertification in critical areas in semi-arid regions are often result of use, overuse and sometime abuse of a parcel. The increasing population pressure and increased resources and expectation has led to desertification in several areas, not everywhere aridity has played a pivotal role. In critical arid desert areas in Kuwait we have seen just fencing and over grasing has significantly increased vegetation, without any irrigation. But steps have to be taken before it is too late.
André Panis, Scientific Associate at French National Research Institute for Agriculture.
Hebron is in Palestine. Palestine as in the sourroundings countries where desertification is running (so as in north of Maghreb), the first step that an agronome ingeneer and searcher can recommand (before land use as grazing soil for breeding cattle) is as follows. If the soil is flat, it is easy to prepare plantation of trees (dig a hole in sandy soil ou in solid and stony soil. Holes should be sufficiently wide for planting a young tree and for allowing them to rooting sufficiently away during the first years of their growing. If the soil is sloping, build "terrasses" of 30 meters wide. "Terrasses" should be horizontal and (against rain erosion) each" terrasse" should be sustained by a very strong "wall" of big rocks, with "interstices" between rocks completed by stones. When "terrasses" are finished, before heavy rainy period dig (at about 70 cm-1 m in depth), big wood of trees (diametre more than 20 cm, length at least 50-60 cm). For instance as possible in Palestine or in Maghreb, use species trees of Mediterranean origin (avoid plantation of Eucalyptus spp. with sterilise soil, under their shadow) . I recommand olive(Olea europaea) and fig (Ficus carica) trees in Palestine and in Maghreb. Irrigate "terrasses" (or at the foot of trees) in the years when weather is not enough rainy in autumn-winter(or in winter-spring). When trees will begin to shadow the soil surface (at least 5 years after) you can foresee under ground, either annual food plants (horticultural species; leguminous family species are the best) )on "terrasses" or seeding leguminous and herbs grazing, (species of seeds convenient for Palestine' climate). Between year of tree plantation and the year of land use under trees, pear attention !: risk of soil erosion if the "terrasses" are not carefully sustained by rocks and stones.
One of the tested and proven ways to avert this process is re-vegetation on instituted in-situ simple water harvesting structures which are prepared on the ground along the contours. These structures include but are not limited to zai-pits, tied-ridges, semi circular canals, rectangular bands and the like. If the rainfall is not sufficient it is important to additional supply water through an efficient method such as drip irrigation especially at establishment but also for sustainability. Sandy soils if prevalent may require additional clayey soils and organic matter from farm-yard manure to improve both water holding capacity and also nutrients for the vegetation. As vegetation cover increases quich maturing tree varieties can be grown. Wind being one of the agents spreading vegetation can be prevented using wind breaks.
Trying to answer your question, first and what I consider the strongest work, you have to locate areas with desertification, including anthropogenic, climatic and environmental factors that influence the development of the phenomenon. However, it can take time is not available.
When researching for my master thesis, I observed that a quick way of evaluation is the use of vegetation index such as NDVI or EVI, dividing the index values in groups of desertification.
In my opinion, the vegetation index is only an evaluation parameter, but if you include the information in climatic zones with the index, you may have a more rapid assessment of desertification areas without considering the complexity of the phenomenon.
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