DESERTIFICATION IN TUNISIA: colonization and lifestyle

AFRICA IS DRY

Sorry guys, but today I am going to confirm my representation of Africa as a dry region.

It seems that Africa had been touched by droughts these last three decades, especially in dry areas (arid, semi-arid, and dry sub-humid). Arid areas, composed of arid, semi-arid and dry sub-humid zones, are characterised by (among others) their rainfall rates (arid <400mm/y, semi-arid 400-900mm/y and sub-humide 900-1400mm/y). It is said in a report (M.Requier-Desjardins et al. 2006) that arid zones are described as hydric deficit areas. Arid zones are the most touched by precipitation decline, and variability has been more observed in arid and West African regions during the 70's (M.Requier-Desjardins et al. 2006).

Some studies state that since the 1970's, Africa has shown a tendency to aridification which is not observed on the same way everywhere on the continent but globally asserted by a rate of precipitation under the normal amount. (MahamanOUEDRAOGO 2001)

Understanding that my thoughts about dry Africa were not too wrong finally, I began to look for information about this phenomenon, something that would define this trend, and if it is truly justified. And a term often returned : Desertification.…....This is Halloween tonight and this word is really adapted to the context, it is a really severe term !

I said above that this tendency was particularly noticed during the 70's, but actually the term already appeared in 1927 in a publication of Lavauden (French zoologist) describing Sahara forests, and a second time in 1949 in North and Central African Republic description by Aubréville. This latter indicates that deserts are appearing in areas where we previously often found 700-1500mm of precipitation ( M.Mainguet 1998). Despite that desertification is not recent, a common admitted definition of the term was proposed by CNUED (Conference Nations United Environment and Development) and used during the Rio Earth Summit. It is said « Land degradation in arid, semi-arid and dry sub-humid areas resulting .from various factors including climatic variations and human activities » (M.Mainguet 1998).

This definition includes human responsibility in this phenomenon, but, actually, adding climatic variations attenuates it significantly. I am not sure whether it was necessary to specify climatic issues, because, the way I understand climatic changes is an anthropogenic phenomenon.

The African continent is known now to have a high population growth and this phenomenon increases the pressure exerted on lands. Moreover, land-use systems are also a determinant element to the arid lands decline. To these pressures are added to the climate issues, characterised by temperature increasing, droughts, and weakening availability of water. As I said, we generally admit that global warming is anthropogenic, so causes of desertification come from human activities’. But, unfortunately, it is also dangerously threatening human populations.

Today, according to the GLASOD and a 2003 teledection study, already decertified regions represent 10% to 20% of the global dry regions (Millennium Assessment 2005). Even if desertification touches each continent, and it is not on homogeneous way, Africa is particularly concerned about this degradation because this continent contains 37% of arid zones (Cité Sciences et Industrie). On this map we can even notice that arid areas including hyper arid and dry sub-humid areas represent more than half of the continent, spread following the climate distribution.

http://www.millenniumassessment.org/documents/document.797.aspx.pdf

What is it about in Africa ?

In my last post, I mentioned the case of the Victoria Lake. Indeed, freshwater ecosystems in dry regions like rivers, lakes, swamps give many services to humanity (food, livelihood thanks to fisheries, tourism, and access to freshwater). Furthermore, freshwater ecosystems are not the only ecological communities to provide services to human populations. Vegetal covers and soils also contribute to services, they provide resources, air and water filtration, water cycle, climate regulation and beautiful landscapes for tourism (M.Requier-Desjardins et al. 2006).

Although, desertification means degradation of these ecosystems in dry regions, instability of these services are usual, particularly in Africa, but scientists have observed that these ecosystem services are on a general trend decreasing on the long term (Millenium Assessment 2005). Water scarcity and hydrologic disorders are actually the most concerned elements by desertification (Millenium Assessment 2005), and the consequences can be dramatic. Indeed, I was surprised to learn that this water disorder could have repercussions on activities like health risks. Actually, a bad filtering of water and air promote tropical diseases (M.Requier-Desjardins et al. 2006), and unhealthy environment, increase the amount of bacteria and damage the human body. Moreover, transports will also be altered by bad quality of air (aerial), and water (fluvial) (M.Requier-Desjardins et al. 2006) and will considerably curb development in Africa.

Dry regions are concerned in particularly developing countries, and populations which have a low rate on well-being indices. Land degradations alter directly livelihoods of the African population. Agriculture and livestock grazing will be affected by infertility of soils, soil salinity that will disturb food security (M.Requier-Desjardins et al. 2006). What I understand is that this cycle of African activities auto destruction is not only going to increase because of the population growth, but also because of the fact that infertility of soils, and degradation of vegetation, water and air quality will generate more efforts from population to maintain their activities and thus, multiply stress on the environment, and vice versa.

Yesterday, a friend of mine posted on Facebook a video of Allan Savory’s conference about his solution to reverse the climate change. This idea is that grazing is useful for ecosystems and mainly for plants, and state that expanding grazing is the exceptional solution to eradicate desertification and give landscapes their health back. I thought it was a great video and I advise you to watch it. But I am still puzzled about it, because I understood that intensive activities on environment generate pressures, and I think that presence of ruminant animals is sane for ecosystems, but I think this solution can be really misunderstood and become a disaster if it is used to excess.