The best time to plant a tree was 20 years ago. The second best time is now.
Well, that's how the old adage goes. But what if we've got it wrong? What if planting trees is not the panacea for climate change it's often touted to be? And what if, under certain circumstances, tree-planting does more harm than good?
These are questions ecologist and biogeographer Prof William Bond would like more of us to begin asking.
He is critical of what he views as a "fetish for forests", which he fears distorts conservation efforts, particularly when the wrong species of trees are planted in the wrong places, like Africa's savannahs and grasslands.
He warns too that this tree-planting frenzy provides industrial polluters with a convenient fig-leaf. It lets them continue to spew carbon dioxide into the atmosphere in return for payments to commercial programmes that ostensibly offset emissions of the climate change inducing greenhouse gas, by planting CO2-consuming trees.
An ecologist with a special interest in savannahs and fynbos, Bond was speaking at the latest Oppenheimer Generations Research and Conservation Tipping Points webinar, titled Managing African grassy biomes: challenges and practice.
The Tipping Points series brings together thought-leaders and researchers on the last Thursday of every month to address key issues affecting development and the environment in Africa.
Sharing the panel with Bond on August 31, were Dr Duncan Kimuyu, a senior lecturer in the department of Natural Resources at Karatina University, Kenya, and Dr Heidi Hawkins, a plant physiologist, ecologist and researcher at Conservation International and the University of Cape Town.
Hawkins and Bond said that while trees helped combat climate change by removing carbon dioxide from the air and releasing oxygen into the atmosphere, the impact of mass tree planting programmes had been grossly exaggerated, misleading and incorrect scientifically.
The World Economic Forum launched its Trillion Tree Initiative in Davos in 2020. Rolling Stone subsequently published this article, Why Planting Trees Won't Save Us, that exposed "the magical thinking around the trillion trees initiative".
Flawed
Bond said equally flawed thinking applied to the African Forest Landscape Restoration initiative founded in Durban in by a group of 10 African countries, each committing to restore a certain number of hectares of degraded landscapes within their borders. AFR100, to use its acronym, has since included in its stated aims, bringing "100 million hectares of land in Africa into restoration by 2030".
Hawkins said these tree-centric initiatives ignored grasslands and how extremely important they are for carbon sequestration.
She said many people did not realise grassy ecosystems were actually a more reliable carbon sink than forested ones.
She said this was because forests, especially tropical forests, store most of their carbon above ground, where they are vulnerable to fires and harvesting.
In contrast, grasslands store as much as 50-70% of their carbon in the soil. Belowground carbon includes plant roots, but most is found in the soil itself. And soil organic carbon was the largest terrestrial store of carbon on Earth, said Hawkins.
So, while planting trees may be a solution in some parts of the world, it risks disrupting the natural diversity of Africa's grasslands and savannahs, while reducing carbon storage in the soil.
Kimuyu said urban development and overgrazing of livestock are among the many threats to the health of Africa's savannahs and wildlife.
He said that today, wildlife represented a scant 4% of the global mammal biomass (the mass of living biological organisms), compared with people (34 %), and livestock (62%). And with livestock numbers expected to double by 2050 (from 1,5 billion cattle to 2,6 billion; goat and sheep from 1,7 billion to 2,7 million), the threat of overgrazing and resulting desertification would only grow.
He said tackling desertification by tree-planting brought its own problems, not least for traditional communities that relied on pastoralism, and which requires vast tracts of grasslands.
Bond also pointed out that "Africa has the largest potential untransformed land that can be used for farming", which means that as the population increases, the pressure to use this fertile land, which included savannahs, would grow too.
What can we do?
On the overgrazing front, Kimuyu said it was important to make sure that stocking rates align with the carrying capacity of grasslands, whether its wild animals or livestock.
Hawkins said although Africa's grasslands were threatened by a range of factors it was not too late to save them from permanent damage.
She said rewilding and building wildlife economies were among the viable solutions alongside better planned carbon-offset programmes that take into account biodiversity and the wellbeing of people.
Wrapping up the discussion, Bond did not mince his words.
Cost
Asked to comment on the AFR100 pledge, which commits countries across Africa to bringing 100 million hectares into restoration and afforestation by 2030, Bond told audience he was astounded at the poverty of "the arithmetic behind these afforestation programmes".
"The impact that they make is trivial in global terms. The cost to Africa is enormous," he said.
"Very often they will be non-native trees, pines and eucalyptus and so on, because they grow the fastest. We are going to be living with them as invasives and bits of plantation for decades, if not centuries," said Bond.
Ultimately, the pledge would have a negligible effect on climate change at a global level. Yet companies, including petroleum companies, were now competing for lots of land to plant trees, "where neighbours will not get annoyed with them".
"It's crazy, and Africa is seen as an easy target," said Bond. "In my view it's fraudulent. So we have to really try to wise up as a continent, as people who can advise on these programmes, foisted on us by others who are too slap, too idle, too lazy to control carbon emissions."
Contacted for comment, Teko Nhlapo, representing the AFR100 secretariat, expressed disappointment at Bond's statements.
The AFR initiative restored degraded forests and lands; "non-degraded forests and lands are never used", he said.
"Prof Bond should provide more explanation on what he means by a 'fetish for forests' by providing country examples and the types of trees that are planted in the wrong place. Our work in the field shows the contrary," said Nhlapo.
The AFR100 initiative "always and simultaneously" brought "win-win" environmental, social, economic and livelihood benefits, which improved human wellbeing and the health of the planet, he said.
The secretariat provided a lengthy list of the benefits the initiative brought at a local, regional and international level. These included, improved diversity, rural prosperity, jobs for women and young people, food security, environmental and human health, and a reduction in global warming, floods, drought, and forest fires.
The Food and Agriculture Organization (FAO) published its first Global Assessment of Soil Carbon in Grasslands in February this year. The report provides a comprehensive analysis of the state of carbon stocks and potential offsets in grassland soils in the world. It states that improving management practices and sustainable grazing management can boost the capacity of soils as carbon sinks, and help countries reach their climate goals.
This story was produced with support from science communication specialists, Jive Media Africa.
