Restoration projects are often designed to restore degraded landscapes, improve livelihoods, and strengthen ecosystems. But what happens to soil carbon when land is restored? What are the climate impact of these activities, and can they be measured? 
 

These are the kinds of questions that emerge when research is closely connected to implementation, a key aspect of the Wyss Academy for Nature's approach. In this interview, Cornelius Okello, Research Associate at the Wyss Academy for Nature and lead of the project Quantifying Disturbance Carbon Losses from Semi-Circular Bunds (SCBs), explains how his team is generating evidence on the carbon impacts of these simple water-harvesting structures and how this knowledge can support restoration efforts on the ground.

Why is soil carbon an important part of this story? 

Carbon itself is not necessarily a bad thing. When it is stored in the soil, it is part of a healthy ecosystem. The concern is when that carbon is released into the atmosphere as carbon dioxide. 

In our semi-circular bunds project, we first have to dig the soil to create the bunds. That disturbance may release some of the carbon stored in the ground. At the same time, the bunds are designed to support vegetation recovery. As the vegetation returns, it recaptures carbon dioxide and stores carbon in the soil again. 

Our hypothesis is that, over time, the benefits will outweigh the initial losses. The challenge is understanding where that balance lies. 

So the project is trying to put numbers behind the hypothesis? 

Exactly. We want to know how much carbon is released when the bund is dug, how much carbon is stored again as vegetation comes back, and how long that process takes. If we lose a certain amount of carbon at the beginning, do we recover the same amount later? Twice as much? Three times as much? Or not enough? That is what we are trying to understand. 

What inspired this project?  

We started working with semi-circular bunds in Kenya through the support of an organization called Justdiggit . Later, during discussions with one of our partners, a question emerged: could digging the soil to create bunds convert these areas to carbon sources and release too much carbon to offset some of their restoration benefits? 

That conversation led to the idea for this project. We wanted to understand how much carbon is lost when bunds are dug, how much is regained as vegetation returns, and at what point the balance becomes positive.  

How are you measuring this in the field? 

We are comparing sites with bunds to nearby control sites without bunds. First, we sampled undisturbed soil, then dug new bunds and sampled again to measure the immediate carbon pulse caused by the disturbance. 

We are also sampling bunds of different ages, including sites established in different years, to build a picture of how soil organic carbon changes over time. Samples are taken at different depths and then sent to the laboratory for analysis. 

What makes the findings useful beyond this single project? 

The findings can help practitioners make more informed decisions. If the results show that bunds are a net positive for climate mitigation, that is useful information. If they show a net negative impact, that is useful as well. It does not automatically mean we should stop digging bunds. Climate mitigation is only one objective. In some places, restoring pasture, supporting biodiversity, or improving livelihoods may be equally important. Our role is not to make the decision for practitioners. Our role is to provide information that helps them understand the trade-offs. 

What have you already learned from the fieldwork? 

One important lesson is that soil type matters. In some places, the ground is so hard or rocky that water may not infiltrate as expected. If the objective is groundwater recharge, that changes some of the assumptions. It suggests that geological information should be considered before digging bunds. 

In some cases, additional techniques may be needed to help water infiltrate deeper into the ground. In others, bunds may simply not be the right solution for that objective. 

You also mentioned governance. Why is that so central? 

Because restoration does not happen in a vacuum. If bunds bring grass back, communities naturally want to use that grass for livestock. In many cases, that is one of the reasons for restoring the land in the first place. But if grazing happens too early or too intensively, the recovery may not last. 

So the question is not only whether the intervention works, but whether the conditions around it allow it to keep working over time. 

If the results show a negative climate impact, how would you handle that? 

We would communicate the findings openly. If the results show that bunds have a negative impact from a climate perspective, practitioners need that information. What they do with it is a different question. There may still be other reasons to implement the intervention. 

I often compare it to knowing the carbon footprint of taking a flight. The information does not decide for you whether to travel. It simply helps you understand the consequences and make a more informed decision. (such as how frequently I can travel).

What do you personally like about this project? 

I enjoy the science behind it: designing the methodology, collecting field data, solving problems as they come up, and seeing the evidence come together. 

I also like that it reflects something important about the Wyss Academy approach. We can look at one intervention from several angles at the same time: restoration, carbon, biodiversity, livelihoods, governance, and monitoring. That gives us a much more complete picture of what is happening on the ground. 

How does this connect to local capacity building? 

The fieldwork also involved training local research assistants from the community. That was important because people should understand what is being done in their landscape and why. The team trained them in sampling procedures, how to use the equipment, and how to follow the protocols. The goal was not only to collect samples, but also to build local capacity for future monitoring activities. 

Who has contributed to the project? 

This project is the result of a broader team effort. The idea and proposal involved several colleagues and partners, including the Senior Research Scientist  from the Wyss Academy Dr. Marie-Estelle Demory, the  PhD Candidate and Research Associate  Simangele Sithole, the  Head of Innovation and Impact at Hub East Africa Sheila Funnell, Menita Kupano from Green Earth Warriors, and Catherine Machungo,  a soil specialist from Hub EAF who made a significant contribution to the project. 

What are the next steps? 

The team is completing additional field sampling, including at partner sites, and sending the soil samples to the laboratory for analysis. Results are expected later this year, after which the team plans to prepare a scientific manuscript. If the proof of concept is successful, the work could support longer-term monitoring of soil carbon and restoration outcomes.Again, the bigger ambition is to generate evidence that helps practitioners make better-informed restoration decisions.