Carbon Tanzania Director Marc Baker discusses some home truths and realities about tree planting as a strategy to deal with deforestation, land use change, biodiversity loss and climate change.
“Tree planting? Do you mean afforestation?”
“No, I think it’s reforestation, like forest rehabilitation, or maybe restoration?”
“Is that active restoration or natural accelerated regeneration?”
“Mmm, I guess, it’s… actually I don’t really know…”
Dazed and confused? You should read on.
I’m sure you’ve all heard this call to action before, I certainly have, it usually starts with a simple ‘google search’ statement such as “deforestation in Tanzania accounts for 400,000ha of woodland loss each year, so we must encourage people to plant trees”.
I just want us to think about that for a moment.
Perhaps the assumption here is that the ~400,000ha of the forest and woodland being cut down every year is for wood fuel and charcoal perhaps, so that by planting trees that could be used for wood fuel or charcoal (in 20 years!) we will be able to genuinely address deforestation? Wrong, charcoal is a secondary biproduct of deforestation, vary rarely is it the primary cause and certainly not at the scale of deforestation we’re talking about.
Approximately 80% of deforestation in Tanzania is driven by shifting agriculture, so perhaps planting trees is going to address the need for agriculture land? Nope, not even close.
Maybe encouraging people to plant trees is about biodiversity? That’s a potentially good argument, so let’s explore that briefly. Forests (defined by 10% tree cover, so virtually all natural standing biomass in Tanzania) are relatively stable ecosystems that have developed the maximum biomass, structural complexity and species diversity allowed bythe limits imposed by localised climate and soil conditions.In this case, if you are a ‘tree planter’ you are suggesting that these highly complex ecosystems, with evolved relationships between perhaps a hundred or more species of trees per Ha in our Acacia and Miombo dryland forests, can be ‘remade’ or ‘recreated’, its biological diversity completely rebuilt? Soil microbes restored? Perhaps there’s something to this argument, where some rehabilitation does work, butit’s very site specific and hugely cost inefficient at any significant scale.
Maybe you are talking about rehabilitating areas close to, or within, already existing forests, so that the seed dispersing birds and bats can ‘do their bit’. Perhaps as a ‘tree planter’ you have a nursery built to provide the complex secondary colonising tree species – GREAT. But wait a moment, If you are in that environment, close to an existing forest, you’ll need to be prepared to guard the tree seedlings from fire, grazing, impala (yes, Impala, perhaps the cause of more seedling loss than any other mammal in northern Tanzania), baboons, elephant and other tree eating wildlife. I think you get the message.
Perhaps it’s about climate? Surely that makes sense, well it does to a certain extent, but not really. It’s complicated, again. The tree planting exercise has to be site specific, permanent, quantifiable and verified – if not it’s completely and utterly useless for any of the claimed benefits.
It’s not that tree planting doesn’t add value. You could argue that long-term, well planned tree planting in urban and peri-urban environments adds to the human habitat. I can agree that mixed indigenous tree species can provide shade for people, canopy habitat and nesting opportunities for birds, which is great. if that’s your focus then great, it’s a cool thing to do, but it does nothing to address deforestation.
So, I’ve set the stage, undoubtedly annoyed someone but hopefully a few readers are engaged. As a fan of observable evidence, the reality is that planting trees in ad hoccampaigns is fairly meaningless, like most examples in Tanzania. Planting non-indigenous trees in a school yard for shade is great but it’s not addressing forest loss, biodiversity loss, providing fuel wood or anything meaningful, apart from shade and perhaps a form of wind break.
Let’s look at tree plantingfrom the forester’s perspective and get some of the definitions right.
First up, forest rehabilitation refers to the rebuilding of forest habitat that I mentioned earlier, including the re-establishment of ecosystem services and productivity. But it does not mean (nor could it succeed) to restore the ecosystem to its pre-existing conditions. Think mixed planting to regenerate for agroforestry, protecting a water course, planting trees in your garden.
Next, forest restoration– this is the big one. It refers to efforts to re-instate ecological processes, to accelerate the recovery of forest structure (I mentioned the seed dispersers already), to the re-establishment of ecological functioning and biodiversity levels towards those typical of a climax forest. Climax forests, it needs repeating, are those relatively stable ecosystems that have developed the maximum biomass, structural complexity and species diversity that are possible within the limits imposed by climate and soil. If a climax forest is the target ecosystem, which defines the ultimate aim of forest restoration, then you’ve got your work cut out, but good for you!
For those of you who follow Carbon Tanzania, you’ll probably have realised that we stop deforestation by working with communities to develop land use plans that define and legalise land and resource use. We protect and measure the protection of forests, we create local employment and all of the architecture needed to stop deforestation, which is essentially, these trees have more value standing than cut down. When that’s the reality for rural Tanzanians you can really get started counting trees saved, a much better metric for Tanzania’s future than trees planted.
And remember, we don’t need to plant trees – trees plant trees. They have been doing it through millions of years of evolutionary history!
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