The Arusha Times

Issue 00597

 Dec 12 - 18, 2009

issn 0856 - 9135 


Trees are not just for Xmas – a call to Copenhagen 
December 2009  

East Africa has some 63 out of the total number of some 100 species of Acacia trees that are to be found in Africa. Acacias, the poor man’s fuel and forage, have developed highly specialised characteristics that make them superbly adapted to the challenges of living in Africa – a continent with all its variability and year on year extremes of climate change. The Temperate world worries when it gets a few inches more or less of rain. The African world worries when for three successive years its gets none. If the world at large is really concerned about mans impact on climate change it does not need grant dependant scientists in East Anglia to fiddle with its data, it just needs to see what man is doing to Africa by counting the dwindling numbers and varieties of Acacias. 

Take the Makayuni to Mtu wa Mbu stretch of road in Northern Tanzania, a wonderfully smooth length of some 30 kms of Japanese laid tarmac and compare this with the Meserani to Makayuni road, a somewhat longer stretch of Italian laid tarmac. In the former there are still some different species of Acacia trees to count, in the latter there are, whistling thorn [Acacia drepanolobium apart and of not much use to man nor beast - just ants], none. The latter stretch had a variety of trees, the living memory of the residents of the area holds that fact – just ask them.  In the 10 years living memory of this resident of the area the rapidly thinning stands in the former suggest that it will not be long before it joins the latter as yet another man made arid and relatively unproductive bit of mismanaged African rangeland. But does anyone care? –Not really as it is just those funny red robed peoples [“who, any rate, would be much better off in trousers doing a proper job guarding someone’s house in Dar es Salaam”], along with their progressively emaciated cattle [“who, any rate, would be much better off dead and not emitting their usual volumes of climate warming methane gas”], who are the immediately apparent losers. That we are ultimately all going to be losers has not, as yet penetrated the policy making classes peering out of their air-conditioned offices in the commercial capital city of Dar es Salaam, at the invariably immaculate and well watered green surroundings. 

Acacias are characterised by having thorns – in fact their name comes from the Greek “akis” and means “barb” or “sharp point” [See Najma Dharani’s book – “Field Guide to the Acacias of East Africa”]. Their thorns take on quite impressive features, as dramatically portrayed in the film “The Gods must be Crazy” when one notoriously hooked thorned variety the “Wait a bit thorn [Acacia mellifera]catches the leading ladies underwear requiring the leading man’s, playing the part of an accident prone elephant dung expert,  less than dextrous  untangling of the situation. The Acacia’s thorns have a survival purpose, by restricting how much they are browsed by livestock and wildlife, and when the barbs are braved swarms of biting ants and rapidly rising levels of toxic leaf sap, as second and third lines of defence, further deter the browser’s attention.  Left alone to themselves, and despite the animals and the odd bush fire, the Acacias generally do ok – it’s just man that they are defenceless against. The cut of the hard steel axe and the subsequent  rising column of smoke from the charcoal burners mound spell a rapidly increasing doom for the species – especially the better hard wooded more productive varieties –such as Abyssinica, Gerrardii, Hockii, Nilotica, Tortillis and Xanthoplea. It is the mature, pod bearing trees that go first, providing more bucks for the effort of cutting them down, and pod bearers provide the seeds for the next generation. No pod bearers, no next generation. 

But surely open treeless rangeland is much better than being “invaded” by all that spikey useless bushy Acacia stuff?  Where the species are of predominately of the less useful varieties this might to some extent be true – but in reality the arid and semi arid rangelands need Acacias – for all the multitudinous benefits they confer. Being leguminous their number one value is in improving soil fertility supporting rangeland productivity and providing a critically needed dry season reserve of digestible protein for livestock and wildlife alike. They are also highly valuable for their root systems which counter soil erosion and create water catchments whilst their foliage provides life saving shade. Lopped branches and fallen trees for fuel wood, honey production from twice yearly flowering, gums and traditional medicinal products from roots and bark infusions are sustainable uses that man has practised for generations.  In many traditional societies the value of the Acacias are well recognised and there are strictly applied controls on what and how much is harvested and by whom.   

The advent of the urbanisation and dramatic increases in predominately impoverished populations have created an ever upwards spiralling demand for low cost fuel for cooking the daily diet of maize meal and, if lucky, beans. Much of this fuel comes from charcoal produced largely from the seemingly infinite tracts of Acacia once found growing freely throughout African rangeland. Now, as the Meserani to Mto wa Mbu road is telling, that infinity has a horizon which is rapidly being approached. 

I will leave it to the better informed scientists to tell us how much carbon is captured by well managed and productive rangeland as compared the rapidly evolving treeless wastelands. I just know that it is a lot and stated to be significantly in excess of the carbon captured by rain forests. So why do we not have any “Save the Rangeland” appeals? Do East Anglians prefer to take their holidays in the Amazon? I will also leave it to the Scientists at the International Livestock Research Institute [ILRI] in Nairobi to tell us that African rangeland reared cattle contribute less than 3% of all methane emissions attributable to livestock production, whilst at the same time supporting the livelihoods of some several million pastoralists and providing Nairobi, and much of the rest of Africa, with an affordable, organic and renewable source of high quality animal protein. Just to put one in the eye of Paul and his fellow advocates for a meat free world it has been shown [not, I hasten to add, by scientists from East Anglia] that just 3 grams of meat, or equivalent livestock product, a day in the diet of a growing African child has a significant and readily measurable benefit in terms of cognitive development and ultimate success in developing a fully functioning intelligence.  I am not one for denying them this chance but I need to remember that this time, I am talking trees. 


Text Box: Makuyuni to Manyara road
Text Box: Acacia trees are characterised by having thorns.

So what to do? Grow trees, the right varieties of Acacia, and plant them, in the right places. Simple really except for one small problem the seeds do not readily germinate. It’s just another Acacia thing. In order for its seeds to survive the long periods of insufficient rain and not infrequent droughts the seeds are coat hardened to withstand the strongly desiccant environment. It is said by many that the seeds need to be tenderised in order to germinate either by passing through the stomach of a ruminant and / or be subject to the heat of a bush fire. The latter may be true, though more die than survive, but the former not so true though those seeds that receive just enough but not too much grinding by the ruminant’s molars are more likely to germinate than those fully ground or not ground at all. The Acacia hard wood species tend to have fleshy pods which are highly edible and nutritious for ruminants, providing a particularly protein rich food source in the dry season. Their ingestion and passage through the ruminants gut leads, ultimately, to the seeds being distributed far and wide as testified by my friend’s Acacias, which have largely derived from the cow manure they have used on their well watered lawn!   

The challenge “boils down” to how to grow Acacias, what varieties and where to plant them. It is a lot to do with caring for an environment where climate challenge [change to challenge is easily done] is an established fact of life, whilst it is the actions of uncaring fellow citizens and the misinformed / weakly applied policies allowing them, that seem to me to be the real change of concern. Just count the trees and see each day their number dwindling. Ruminant guts and bush fires apart by application of the appropriate technique Acacias can be induced to germinate and that magic moment of life, its reproduction, follows. Such a technique is likely to include the physical collection, storage with insecticide, preconditioning [soaking Acacia seeds in hot water works for some species but not the harder tougher ones – more physical abuse, otherwise known as scarification, is needed] and sowing of the seeds in long-range weather forecasted periods of prolonged rains. Maybe someone should ask Copenhagen to allocate a proportion of the carbon funds for the management of rangelands inclusive of the planting of Acacias – a present for the earth that will last longer than Xmas.



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