Sustainability: Five Firewood Trees

Hardwood logs

A blustery cold front made using the lovely wood burning fireplace in my lounge desirable.The batch of hardwood I bought in 2017 has proved enough for three years. Yet given that trees for firewood are being overharvested by individuals as well as businesses, what five trees would make the firewood industry sustainable?

For a little background, the hardwood I bought came from a company with a reputation for sustainable harvesting of alien hardwoods. That it delivers in large quantities all over Gauteng was an added bonus. Yet unless these alien trees are replaced, what is in theory a renewable resource has probably become a scarce one; I have noticed that the same company sources some wood from Botswana. Which might be sustainable. Or it might not be. One would have to find out what their policy and practice is in regard to this foreign source of biomass energy.

Besides the cold front, this question arose due to an observation in my suburb of Orange Grove. A home with five trees is now a home with chopped wood. The base of the trees evidence of where the firewood comes from. I have seen this elsewhere. Are these PSHB infested trees? Or not? I sense that they are not and am strangely shy to ask. Firstly, it is lockdown. Secondly, if people are chopping down urban trees for firewood, asking the reason for their action might be considered intrusive. After all, what happens on private property is private. Only trees on the Protected Trees list attract penalties for felling. Thirdly, if people have lost their source of regular income, asking might heighten their sense of shame that they have come to this.

Besides, unless I can provide an alternative, what is the use of asking? Enough for me to observe. Enough to connect intuitively with what might be going on. What I know is that firewood remains a potential form of sustainable biomass energy. Yet it requires strategic planning and management by the city. Or by its citizens, since the city is otherwise preoccupied.

Given the lockdown, I am focused on how the people in my suburb, and more broadly in my ward, might meet their firewood requirements. At the back of my mind is the sight of thin trees growing in fields of wheat in India. Harvested every two years, I was told, for making matches! The tree farming system repeated – trees grown as ‘crops’.

One element: Many functions

My choice is guided by the second principle of permaculture: One element; many functions. Each tree, being one element, provides a number of benefits or functions. It is a utilitarian principle which ordinarily would make me a little queasy, for all things have a right to exist. Each has its own purpose. Simply being is a purpose. Yet I have made peace with this inner battle for it seems that the only way to protect biomes and natural eco-systems, including indigenous forests, it to make them off limits to people outside these spaces. To promote protection of natural spaces requires supplying as many forest products as possible where they are to be utilized or consumed.

Food Forests are the best way I know to get buy-in from people to personally invest in sustainable environmental and ecological infrastructure.

Currently, in the same way that we have a lockdown for Coronavirus, we have a lockdown for PSHB infestation. It too is a pandemic. It too is a plague. At least those of us who support the protection of heritage trees and sound management of Johannesburg’s forest, have a self-imposed lockdown for PSHB. The rules for normalizing the reality of COVID-19 are: wear a facemask; keep a safe distance (2m is what I aim for); wash your hands regularly. The primary rule for PSHB (borer beetle) infestation is: DO NOT MOVE FIREWOOD from one area to another. In other words, source your firewood locally. From a sustainable perspective it means: Grow your own firewood! Collectively and individually.

In case you need further persuasion, it is said that compared to fossil fuels, wood burning is sustainable. Provided you design for a ‘clean burn’. And adapt your consumption to sustainable availability of each product. I think I am not the only person who finds this an ongoing challenge. So far removed are we from the sources of what we consume that we tend to think of products as infinite. And disposable. This is not necessarily true…

Biomass Energy: Five indigenous trees

Trees are most certainly a source of renewable energy. My choices have been informed by the types of trees that will grow in and around Johannesburg. I have also chosen trees that can be used for heating as well as for braaiing, for not all firewood is suitable for both purposes.

Dichrostachys cinereal (Sickle bush)

A small, drought resistant tree, it makes a slow burning firewood. Additional beneficial uses include:
 Fixing nitrogen in the soil
 Curbing erosion
 Termite resistant hardwood ideal for fence poles
 A living-fence for fodder
 Traditionally used as a local anesthetic for snake bites, scorpion stings and tapeworm cure…and a host of other medicinal uses
When grown close together the sickle bush is impenetrable. It is therefore probably most useful for urban goat farmers. While I don’t know anyone in Orange Grove who keeps goats, I have heard that in Alex some people do… (This deciduous tree has thorns that could damage tyres.

Vachellia erioloba (Camelthorn)

A highly valued slow-growing hardwood prized for the following additional qualities:
 Resistant to termites and borers.
 Tolerates severe drought and severe frost
 Seeds can be used as a coffee substitute
 Its gum is edible for both humans and animals
 Different parts of the tree are used traditionally to treat aliments as diverse as tuberculosis, ear infections and gonorrhea
In the wild, the presence of Camelthorn suggests that groundwater, at a depth of up to 60m, is available. (Please note that this tree is a protected tree in South Africa.)

Vachellia karroo (Sweet Thorn)

This high carbon sequestration tree is used as fuel and to make charcoal. It burns with little smoke and is odourless.
 Provides excellent bee fodder
 Is attractive to a wide variety of birds and insects
 The edible gum can also be used for glazing pottery
 Inner bark is used to make rope
 Useful as a windbreak on large properties

Senegalia caffra (Common Hook Thorn)

If grown close to a water source is can reach a height of 14m. When mature it is frost and drought resistant. It is also valued for the following benefits:
 Making baskets from the twigs
 Making Xhosa smoking pipes from roots
 Tanning leather (light brown)
 Fixing nitrogen into the soil
 Open canopies allow light to filter through, enabling plants to grow beneath it
Because of the latter two benefits it might be a very useful tree to include in urban permaculture where space is at a premium.

Celtis Africana (White stinkwood)

A fast growing, frost and drought resistant tree. It includes the following benefits:
 Shade
 Carbon sequestration (one of the top five in Gauteng)
 Produces good quality charcoal
 Used in construction, from ladders to plywood, to wooden toys
 In traditional medicine it is used to treat a number of ailments, including pleurisy

Combretum apiculatum (Red Bushwillow)

A small termite resistant hardwood tree popular for making charcoal. Additional benefits include:
 Mature leaves provide fodder for browsing animals
 Making pestles and other small items
 Making tea from the leaves
 Edible gum
 Once established it is frost and drought resistant
However, please be aware that the fruit and seeds are poisonous to many animals, including humans.

In conclusion, I hope you feel motivated to plant many of these trees. And to be patient with their growth patterns. And to grow to love them so much that you will do what is necessary to extend their longevity. It might mean taking only winter prunings. And cutting back on the number of fires you light in your fireplace. And, like me, adding blankets to your list of sustainable heat sources. For while we have many indigenous trees capable of providing South Africans with biomass energy, the truth is that our consumption already outstrips the rate of growth of our own trees. Botswana and Namibia are possibly being denuded to feed our overconsumption.

A diversity of energy sources as well as designs that increase efficient and clean burning are thus urgently required; I was amused by the simplicity of the following rocket stove design:



Assessment of the Gauteng Firewood Market and the Origin of Protected Tree Firewood Products Sold (2007):

Burning the right firewood for maximum heat output and minimum environmental impact