usual for a tract of land to pass from virgin forest to abandoned bush, when the low- 

 lands are cultivated, within a period of eight or ten years. 



Dealing with the coffee and tea planter in Ceylon and Madras, Colonel Beddowe, 

 Conservator of Forests, Madras, wrote in 1876 'It must not be supposed that coffee is 

 at all a permanent cultivation — many deserted estates show that it is very little better 

 than the shifting cultivation of the hill man. It pays a coffee planter to take up a tract 

 of primeval moist forest on our mountain slopes for a few years; he gets bumper crops 

 the third, fourth and fifth years but denudation of the soil goes on rapidly and it does 

 not pay him to keep it up many years. Can we restore the grand old forest with all its 

 climatic influences? A thorny wilderness takes its place'. This was written 76 years 

 ago. Vogt has presented the same grave picture as happening in the world today. Popu- 

 lations, he continues, have therefore to concentrate above 700 metres. The best agri- 

 cultural land in the higher altitudes lies in the interment valleys but in part, because 

 there is an insufficiency of land and the best lands are in the hands of wealthy owners, 

 the mass of farmers are crowded on the slopes where they practice shifting cultivation 

 (milpa) which has resulted in a very high percentage of slopes throughout Latin America 

 becoming de- vegetated. The usual results are of loss of soils and aridity, with flash 

 floods with their consequent scouring action, interspersed with periods of little or no 

 water in the rivers. Mr Vogt continues 'The land settlement pattern in Latin America 

 has resulted in the extremely grave situation that there exists probably from twenty to 

 forty million displaced persons. They are displaced in the ecological sense, namely 

 that their present relationship to the land is destroying it at an accelerating rate, not 

 only in the highland areas where they live, but in the lower areas affected by river 

 flows. Many millions of acres of soil have become seriously eroded in Latin America 

 and, as Professor Stebbing has described in the case of the Sahara, deserts are on the 

 march. One of the worst instances of this land pathology is in St Salvador, where two 

 million people, increasing at the rate of forty thousand a year, have available for agri- 

 culture only about an acre per capita, and much of this land is of low productivity'. 



How many displaced persons, using the term in Vogt's sense, are there at the 

 present moment in Africa? It is a natural query. V^e may also ask at what accelerated 

 pace, compared with the past, are the processes of degradation in erosion, desiccation, 

 sand penetration-the term varies with the conditions being produced — proceeding in 

 Africa today? According to French investigators the Sahara has advanced southwards 

 during the last three centuries at the rate of half a mile a year! 



From the studies I have made I would record the opinion that a belt of country in 

 Africa betv/een the 13° and 15° parallels of latitude and stretching from French Senegal 

 in the west at EI Obeid and Kosti on the White Nile in the Sudan to the east, is at the 

 present day in the Intermittent Rainfall stage, and is still in a condition when man may 

 undertake operations to stop further degradation and the onward march of the desert. 

 It is impossible, nor is it necessary, to deal here with practical methods which could 

 be undertaken. 



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