A look at Carbon – a “Co-benefit” of Agroforestry


Results and White Papers

Forest Gardens across Senegal, Kenya, Tanzania, and Uganda sequester an average of 62.8 metric tons of carbon per garden

By Guest Blogger Lauren Cooper

You’ve heard of carbon.  You’ve heard of emissions.  What does that have to do with a single cashew tree growing in Africa?

Carbon analysis is being incorporated at all scales of land use planning in forests, cities, wetlands, and agriculture – including Trees for the Future forest garden projects. But why is carbon so important?

Simply put, carbon is important because of climate change.  Carbon is one of the most important greenhouse gases (GHGs) contributing to climate change. The more GHGs, the warmer our atmosphere gets (as implied by the term “greenhouse”). We release GHGs when we burn carbon-based fossil fuels (e.g. oil or gasoline). This increases the amount of carbon in the atmosphere because we are pulling this carbon from deep within the earth, where it would be otherwise undisturbed.  While burning wood or any other carbon based plant matter also releases carbon, it is carbon that is already cycling in our atmosphere and in living things, like trees. However, it should be noted that sweeping deforestation across the globe also contributes to climate change because of the dramatic release of high levels of carbon that contributes to heating.

Plants take up carbon during photosynthesis and use molecules of carbon to create their physical structures. In fact, it’s estimated that the average dry weight of a tree is about 50% carbon. All living things are made of carbon but trees offer an opportunity to store this carbon for long periods considering their long life-span. Further, trees create carbon-rich ecosystems which store carbon in leaves and fine roots that later fall off and become carbon-rich organic matter in litter and soil.

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Carbon – an Important Co-benefit

The work of Trees for the Future is improving livelihoods by planting trees for food and other products and providing the support necessary to care for them. These projects are improving the lives of individuals through economic development, training, improved nutrition, and increased resilience to market and climate shocks.

Planting trees offers many other benefits, which can be referred to as ‘’co-benefits”. These include reducing erosion, creating natural wind barriers, providing habitats, and improving the local climate, air filtration, and shade provision.

Calculating the carbon storage allows us to measure the “co-benefit” of carbon storage in Trees for the Future projects.  But this benefit is unique in that it is the center of a massive global, human, scientific, and political conversation about climate and our future. Trees are part of the solution and calculating carbon helps us understand how planting trees is removing carbon from the atmosphere and storing it.

The Measurement Process

To estimate carbon storage in landscapes, the International Panel on Climate Change (IPCC) is a scientific body that has created guidelines with input from top scientists across the globe. This group directly informs the United Nations Framework on Climate Change (UNFCCC), which brings countries together to tackle climate change.  Trees and forests are an important part of this global conversation because they are able to store large amounts of carbon over time.

The IPCC guidance on carbon measurements can be found in the 2006 IPCC Guidelines for National Greenhouse Gas Inventories, Volume 4: AFOLU (Agriculture, Forestry and Other Land Use). These texts provide expert direction for countries, project planners, and landholders looking to calculate carbon.

How it works

Detailed carbon analysis involves physically measuring tree trunk and branches and using formulas to estimate the biomass. It can even involve cutting trees down, drying them, and measuring the dried matter to get the highly accurate measurements. This can be done for individual trees or in a plot, and collected data can be used to estimate larger areas.

Unfortunately, this can be an expensive and time-consuming process, and damaging trees has obvious downsides. Because of this, the IPCC has created default values for estimation when a high level of detail is not necessary. Incorporating default values allows for a general estimate based on the land cover, land use, and ecological features without the expense of measuring trees across many landscapes.

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Measuring Results

Carbon is another way to measure the results of TREES’ activities. To estimate the carbon stored in an average Trees for the Future forest garden site, project location in the Global Ecological Zones were considered (these “eco-zones” inform the IPCC guidelines). Default values for agroforestry as well as forests by ecological zone were included.

Looking at the ecological zones allows us to better incorporate ecologic information (i.e. water, growth, and carbon density) that impacts the total carbon that can be stored in a landscape. While carbon grows slowly from small trees until they are full grown, the total capacity of a given landscape is largely dependent on its ecological conditions. For example, a dry region will not hold as much carbon as a dense rainforest.

In Trees for the Future’s Forest Garden program, the average hectare (2.4 acres) sequesters 62.8 metric tons of Carbon. At a rate of 4,000 trees per Forest garden, this equates to an average Carbon offset of 34.6 pounds of Carbon per tree. This carbon estimate below takes into the account the different capacities across the landscapes where Trees for the Future works to create a single carbon estimate using IPCC default values for agroforestry and forests.

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Linking Local with the Global

By measuring carbon, we link the local benefits of forest gardens (food and income) with the global benefits (carbon storage and climate change). Planting trees affects not only individuals and families – it has a positive impact on the entire global community.

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