planting trees

Introduction

Before we get onto our specific projects, let us first take a look at the general concept of planting trees for the purpose of carbon sequestration.

Trees are remarkable natural engines for capturing and storing carbon. Through the process of photosynthesis, they literally extract carbon from the air and turn it into wood, leaves etc., whilst generating pure oxygen as a waste product.

Another great (but little known) fact about trees is that, rather than reaching a peak of sequestration in middle age and then deteriorating, they actually keep on hoovering up carbon at ever greater rates throughout their whole lives. So when you plant a tree, you typically get 50-500 years of continuously increasing payback.

It’s hard to imagine a cheaper, more accessible and more efficient way to extract carbon from the atmosphere.

In this article we will look to answer some of the key questions associated with tree planting projects.

Where to plant trees

Tree planting projects in different locations around the world deliver incredibly different levels of carbon sequestration.

A sapling planted in the tropics typically grows into a productive carbon sequestering tree within 10-20 years, compared with 50-100 years in temperate and 80-120 years in boreal climates, which is extremely important given the timeline of our climate change objectives.

Once mature, a tropical tree typically sequesters carbon at a rate around 2.5 times faster than one in a temperate middle-latitude forest and 3.5 times faster than in a boreal northern latitude forest. This is primarily due to the year-round growing season, coupled with the fact that stable temperatures and high humidities enable tree leaves to open their stomata (gas exchange pores) to their full capacity for photosynthesis.

When we also factor in the much lower prices for land and labour in most tropical countries, we discover that well-managed trees in the tropics commonly deliver 20-30 times more carbon sequestration per unit cost than locations at higher latitudes.

That’s why we plant all our trees in the tropics.

Why Africa?

Our tree planting projects are focused exclusively on Africa for a number of reasons.

The first is that we are very familiar with the continent. Almost all of us have been involved in safari and conservation for many years. We have a deep passion for the continent, have decades of experience of living and working in remote and rural areas and, perhaps most importantly, we have the friendship and trust of local people.

The second reason is that, on top of the incredible carbon sequestration statistics, there are other major advantages to be derived from planting trees specifically in Africa …

Available land

In sub-Saharan Africa human populations are continuing to grow, which is putting increasing pressure on land use and causing widespread clearance of forests for agriculture.

However, in recent years it has become increasingly apparent that conventional western agriculture, with wide open fields, is not the best way to farm in the heat of the tropics.

The traditional form of farming in these parts has always been multi-storied agriculture, where large trees provide shade for medium-sized crops like bananas, with maize and beans down at ground level. This mixed agriculture provides protection from the tropical sun, stabilises the humidity, reduces water loss through transpiration, maintains soil fertility and provides economic buffering against the failure of any one crop.

The current situation has provided us with a unique and enormous opportunity to re-educate farmers and provide them with saplings, in order that they can return to the practise of mixed agriculture, improving their output, whilst also sequestering carbon.

There is presently more land available tree planting than we can cope with, which is a nice problem to have.

Alleviating rural poverty

The vast majority of the people who live in the areas in which we operate suffer from the deprivations of rural poverty.

One of our primary aims is to help alleviate this poverty, which we do by handing out our tree saplings free of charge, enabling people to improve their lot without having to invest any cash. So long as a farmer comes to collect the young trees in person and undertakes to plant and look after them, that’s good enough for us. They are our honest, hard-working neighbours, who we trust to do their utmost to honour the bargain.

In recent years we have started to provide a wider range of trees, ‘branching out’ from our focus on indigenous forest trees and including other species which can deliver a greater economic boost to the farmers, like mango trees, avocado trees and pecan trees. They all suck up carbon like it’s going out of fashion.

Protecting biodiversity

There’s little worse for biodiversity than land stripped bare for agriculture. The re-establishment of mixed agriculture provides far greater opportunities for a wide range of indigenous species to prosper. This creates much more effective buffer zones for areas of protected forest (such as the famous Ngorongoro Forest, which borders one of our areas), reversing the trends of species isolation and gene-pool reduction.

Meanwhile, the stabilisation of ground-level humidities and increased transpiration go a long way to restoring the local microclimates that existed before the indigenous forest was cleared.

Environmental education

Our tree nurseries also contain simple classrooms, where local farmers and schoolchildren can learn about the water cycle, the carbon cycle, biodiversity and the critical importance of trees to the ongoing health of their natural and agricultural environments.

These people are keen to look after their own lands and are more than capable of doing so, once they have been equipped with sufficient knowledge and understanding.

Quantification

Fundamental to the process of offering carbon credits is the quantification of how much carbon dioxide a tree can sequester from the atmosphere each year.

Unfortunately this is a rather complicated number to calculate.

The only truly accurate method to assess how much carbon a tree has sequestered in its lifetime is to cut it down, chop it up into bits (including the roots, trunk, branches, twigs and leaves), dry it all out and weigh it.

But we want to know how much carbon is sequestered each year.

Unfortunately we can’t simply divide the total number by the age of the tree, because the rate at which it sequesters carbon varies enormously and in a non-linear way throughout its life.

Young trees are pretty useless at sequestering carbon until they reach a critical age, where they stop shooting up and start to fill out. In the next section, we describe how we get around this issue.

The bottom line is that, after endless calculations, we have reached a safe-side estimate that our tropical trees are capable of sequestering 92 kgCO2e per year, equivalent to 25 kg of carbon.

Delayed gratification

One of the greatest problems with using trees to sequester carbon is the inherent time delay between planting a sapling and it growing into a really productive absorption machine.

We overcome this issue in two very important ways.

Using tropical trees

In addition to their increased capacity to sequester carbon, tropical trees also offer the fundamental advantage of maturing much more quickly.

The Critical Age is defined as the point at which a tree switches from growing upwards to growing outwards, after which the carbon sequestration becomes far more pronounced. For a tropical tree this is typically around 10-20 years, compared with 50-100 years for a temperate mid-latitude tree and 80-120 years for a high-latitude boreal tree.

Planting tropical trees therefore greatly reduces (but does not completely eliminate) the delay in carbon gratification.

Pre-planting trees

Fortunately for us, our projects started planting trees many years ago, before the trade in carbon credits became a thing. We did it because it seemed like the right thing to do and we financed it ourselves and through the kind contributions from safari travellers passing through.

This means we were able to start out with a huge stock of already-matured trees for which carbon credits could be sold.

When we receive payment to plant more trees, we are therefore able to allocate carbon sequestration from trees which are already mature, whilst using your money to plant new trees. In other words, the work of sequestering your carbon emissions starts immediately.

Furthermore, since the trees continue to absorb more and more carbon as they mature, the sequestration capacity that you have paid for will continue to deliver increasing returns every year through the life of the trees. All you need to pay for in subsequent years is an ongoing maintenance fee that enables us to continue planting a smaller number of trees to offset for natural lossage.

Geographic mismatch

Another question that we are often asked is whether planting trees in Africa is an effective way of offsetting carbon emissions generated in other parts of the world.

The short answer to this question is ‘yes’.

Unlike temperature, which can vary enormously and create pronounced gradients around the world, gases are very effective at equalising over great distances, providing consistent dilutions across locations.

The dilution of carbon dioxide and other greenhouse gases can increase slightly in the immediate vicinity of large and active sources of emissions (such as particularly ‘dirty’ cities, coal-fired power stations and factories), but these are relatively minor and transient effects.

So when our African trees extract carbon dioxide out of the air, the (heavily diluted) effect is experienced almost simultaneously around the globe

Tricks and cons

On an earlier page entitled Tripwires, we explained some of the areas where companies may be trying to take advantage of their customers when offering environmental services.

Since tree planting is so important to us, here we have taken a slightly deeper dive on the pitfalls in this particular area.

Cheap carbon credits

The number one tell-tale sign of an inadequate or fraudulent offsetting scheme is that the carbon credits they are far too cheap. This phenomenon is extremely widespread and highly damaging to legitimate projects.

At the COP26 conference, the OECD recommended that a carbon price of USD 147 per tonne should be assumed globally by 2030. For tree-planting projects this implies a price per tree of at least USD 3.68 in the tropics, USD 1.47 in temperate regions. You can multiply these amounts by the number of years the tree is expected to continue sequestering carbon, which means that the correct price for a tropical tree is closer to USD 100. We usually charge USD 4.00.

Underpricing is usually deployed by companies which are trying to entice individuals to offset their lifestyles for ridiculously low prices.

For example, one very well-known scheme (which is actually referenced by Wikipedia) offers personal lifestyle carbon offsetting for GBP 5.00 (USD 7.00) per month. That represents 10-35% of the actual cost. They are basically making up the numbers to try maximise sales, irrespective of whether or not the customer’s lifestyle is adequately offset.

The main mechanism that these companies use is to massively overstate the carbon sequestration per tree. One project we reviewed in England allocated the carbon sequestration for the first two hundred years of the life of their trees into the purchase price (we only include one year), whilst simultaneously only allocating one square metre of land per tree (we typically work on 50 sqm). These claims are so farcical that they are surely criminal.

When you scratch the surface of many tree-planting projects, you quickly discover that that not only are they overstating the carbon sequestration by at least an order of magnitude, but that they will not offer any meaningful carbon sequestration for at least 20-30 years (the time it takes the tree to grow to its critical age), which is absolutely useless for tackling climate change.

Delayed gratification

Perhaps the most fundamental issue with planting trees to offset emissions is that new trees do not start to sequester significant carbon for decades (tropical 10-20 years, temperate 50-100 years, boreal 80-120 years).

In the context of combating global warming, this delay is totally unacceptable. We cannot carry on adding carbon to the atmosphere now on the promise that we will extract it in the decades to come.

We get around this issue in two ways.

Firstly we plant all our trees in the tropics, where the year-round growing season and warm humid climate enable them to reach maturity much faster.

Secondly, we pre-plant trees, so that by the time you buy a tree from us, it has already reached an age where it can effectively sequester carbon. Simultaneously we plant at least two new trees, in order that to maintain a stock of mature trees as the demand grows exponentially.

We urge you to be wary of projects which do not take these or similar measures.

Tree longevity

Many companies that offer carbon offsetting make an assessment of your carbon footprint, figure out how many trees they need to plant per year and then milk you for that amount year after year.

This is very wrong.

Once planted, your trees will keep on growing and sequestering ever increasing amounts of carbon for decades or even centuries.

This means that you don’t need to keep paying the same amount every year. Once you have paid for your initial tree-planting, in subsequent years you only need to pay a modest top up, to cover for any natural lossage (due to drought, pests and wood poachers).

You may well choose to contribute more to tree-planting each year, but you will do so in the knowledge that you are doing it voluntarily, rather than being royally stitched up.

The problem with plantations

If you were intent on planting lots of trees in Africa, your first thought may be to acquire land and create vast plantations or to buy up recently-cleared farmland and replant indigenous forests.

Unfortunately plantations don’t tend to work in the long run.

With increasing human populations, productive land in Africa is in high demand. Projects which effectively steal land from local people tend to be very unpopular and short-lived, more often than not reaching a sudden and rather sticky end. When all the trees get cut down and burned, you’re back to where you started, the carbon is no longer sequestered.

Our approach is totally different,

We work with local farmers to restore the traditional systems of multi-storied agriculture, which is a genuinely sustainable and desirable model, leading to decades if not centuries of continuous and reliable sequestration.

The sapling sting

Another issue that applies to tree planting projects around the world is what we refer to as ‘the sapling sting’.

There are lots of projects out there where tree planting is just a numbers game. All they do is raise the saplings, get them in the ground and tick the box.

Needless to say, most of these young plants don’t make it through to maturity. If they aren’t eaten by goats, they’re cut for poles or succumb to pests. Often they aren’t even thinned out, so each successful tree needs to outcompete a hundred neighbouring saplings.

Periods of prolonged dry conditions represent an enormous further challenge, since a sapling is only usually able to survive a drought after it has reached its fifth year.

These young trees need careful and diligent tending, you can’t just stick them in the ground and leave them to look after themselves.

Organisations that support this type of negligent planting regimes often charge their customers ridiculously low prices per tree (anything under USD 2-3 per tree is highly dubious), but their success rates for actually producing trees which are large enough to deliver any sensible carbon sequestration are often appalling.

Any carbon neutral certification derived from this kind of project won’t be worth the paper it’s written on.

For the record, we estimate that around 85% of our trees successfully reach maturity. There are plenty of projects out there which deliver returns substantially below 10%, some are even below 1%.

We strongly recommend that you only support tree-planting projects which reliably deliver a high percentage of long-lived mature trees.

Passive carbon

Another rather controversial area is where projects sell carbon credits for not doing something, for example not cutting down a forest.

Obviously there are parts of the world where forests are under threat and where protecting them makes more sense than losing them and then replanting. Often this process involves costs, in compensating local people for not consuming their natural resources, or for patrolling and monitoring.

But where does this end? Can we all start selling carbon credits for the trees that stand at the end of our gardens?

Whilst we don’t want to go as far as recommending that you avoid this type of carbon credit, we would like to urge caution and suggest that we take extra care when checking the legitimacy of passive carbon projects.

Next article

Karatu Tree Nurseries

Located in the Karatu area of Tanzania, our primary carbon sequestration project works with local farmers to plant trees and reinstate traditional multi-tiered agricultural practises.