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ANALYSIS: Think twice about the ‘Spekboom challenge’. It could threaten fragile ecosystems

South Africa has gone spekboom crazy. The public and large corporations alike have jumped at the opportunity to offset their carbon footprints by planting Spekboom all over the country. This movement was dubbed the “Spekboom challenge” and has gone viral. 

A large online campaign has called on every person in the country to plant 10 Spekboom plants. This, the argument goes, will help fight climate change and absorb carbon from the atmosphere.  

But burning questions remain: can our climate woes be fixed by the Spekboom challenge? And could the national planting campaign have unintended, negative consequences for the environment?

Back to basics: Spekboom does what?

All living things consist of carbon, among other compounds. Plants have the amazing capability to take carbon out of the atmosphere in huge amounts and store it (as evidenced by the tons of biomass they can consist of, think of the giant Yellowwoods in Tsitsikamma forest). 

This is why fossil fuels like coal and petrol - which formed from millennia of fossilised plant material - are packed with carbon. This carbon is released into the atmosphere when we burn these finite resources. 

The idea behind the spekboom challenge sounds simple, which is possibly why it’s become so popular. The theory goes that we can plant spekboom to absorb carbon in the atmosphere and reverse the effects of climate change.

Why the fuss about Spekboom?

Many succulent plants have a special ability to absorb large amounts of carbon, even in very dry, harsh environments. So why is everyone talking about (and planting) Spekboom? 

Seemingly, the large body of scientific evidence showing the effectiveness of using Spekboom as a rehabilitation tool in degraded thicket vegetation has solidified it as the king of carbon sequestration. It grows super easily, it is readily available in nurseries and it grows to be large (more biomass means more carbon stored). In short, Spekboom seems to have become the charismatic ambassador of a movement.

How much would we need to plant to combat carbon emissions?

It has been widely reported that Spekboom can absorb and store around 4 tons of carbon dioxide per hectare per year. This is possible but only under very specific conditions, in rehabilitated Thicket vegetation where Spekboom is indigenous. (Read Africa Check’s fact-check here.)

While this number has limitations, let’s run some calculations with it and see what it means at a national scale. 

In 2015, carbon emissions in South Africa were estimated at 9.8 tons of carbon dioxide per person per year. If we go with the widely reported carbon sequestration figure for Spekboom (around 4 tons of carbon dioxide per hectare per year) each person in the country would have to plant 2.3 hectares of Spekboom - this is equivalent to three rugby fields. This adds up to a total of 1.4 million square kilometres to offset the entire country's yearly carbon emissions (see my math here). 

That means we would have to plant the total surface area of South Africa, Lesotho, Eswatini (and still fall short) to sequester just one years worth of South Africa’s carbon emissions. And this doesn’t take into account the carbon that will be emitted into the atmosphere by the loss and decomposition of existing vegetation that would be destroyed to plant the Spekboom. This leads us to the next important, and overlooked, question.

The challenge could have negative, unintended consequences

Emerging research is suggesting that restoring natural habitats is more effective at carbon sequestration and improving ecosystem services (like water and air purification) than simply planting one type of tree or plant.

Spekboom is indigenous to the Summer Rainfall region of South Africa and Namibia in specific habitats. It should not be planted into habitats where it is not indigenous, which happened in the past week where a well-intentioned Capetonian planted Spekboom in critically endangered Cape Flats Sand Fynbos. In this habitat, Spekboom could potentially outcompete the already rare flora and would not have any increased climate change mitigating potential than natural vegetation. Additionally, fields and fields of Spekboom (a monoculture) would not support the diversity of animals and microbes that have evolved to live in natural veld and could cause ecosystem collapse and extinction.

Even in regions where Spekboom is indigenous, it should never be planted in natural veld without consulting a rehabilitation specialist. Spekboom has been bred into four different strains that are commercially available, and many different strains are known to exist in nature. Planting nursery stock or even wild strains in nature that do not correspond to the wild-growing genotype could cause what is called genetic erosion. This could have unforeseen consequences and impact the evolutionary trajectory of wild populations.

So what about all your Spekboom?

The Spekboom challenge has had significant positive effects on South Africans’ awareness about indigenous flora (even if it is only Spekboom for now). The challenge has led to an astounding buy-in from the public and awoken the climate activists in millions of people.

This new awareness and actions need to be targeted toward well thought through, scientifically and environmentally sound action. Unfortunately, there is no one size fits all solution to complex systemic issues such as climate change - although it would have been a relief if it had been as simple as expanding one's succulent garden to cover even the mighty Drakensberg Mountains.

By all means, plant Spekboom in your garden if it gives you joy. Additionally, consider other indigenous plants that have evolved to grow in your area and could be just as effective in fixing carbon in an urban setting. After all, South Africa has incredible biodiversity. Let’s celebrate it responsibly by planting an array of indigenous plants, supporting habitat conservation and vegetation restoration/rehabilitation.

Elzanne Singels is a botanist and environmental consultant specialising in the fields of plant conservation, regenerative agriculture and archaeo-botany. She has conducted research on the flora of the Cape Floristic Region and obtained her MSc in Conservation Ecology. She is currently on the cusp of completing her PhD in Archaeology which focused on the edible plants of the region. Read more about her research and visit her instagram.

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