Many African governments have set ambitious goals to plant trees as a way to combat climate change, restore degraded landscapes and improve livelihoods. The Kenyan government has pledged to plant 15 billion trees by 2032 to increase forest cover in the country to 30%. It has also urged every Kenyan to plant at least 50 trees in cities, degraded rural areas, and on farms.
Including trees in smallholder farming systems is particularly important, given the central role of farming in Kenya’s economy and small farms’ vulnerability to climate change. One promising approach is agroforestry, a farming approach where trees, shrubs and crops are planted together to enhance soil fertility, boost biodiversity and improve farmer livelihoods. For example, in Kenya, smallholder farmers often grow maize and beans alongside fruit trees such as mango and avocado. Trees also provide fodder for animals and fix nitrogen in the soil as a nutrient for plants.
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Tree diversity makes landscapes more resilient to pests, diseases and changes in the climate. When an area has many different trees, these provide a habitat for a wider range of wildlife such as pollinating insects and birds. To create more sustainable, thriving landscapes that benefit both people and the planet, tree diversity should be a central part of restoration efforts.
Yet, many tree planting projects focus on the number of trees planted rather than the diversity of species. For example, Kenya’s 15-billion-tree initiative has made little information available on how many different types of trees are being planted and how they are chosen.
We are conservation scientists who study how people and nature interact, exploring the connections between ecosystems, biodiversity and human behaviour. We interviewed 620 smallholder farmers in Vihiga County, western Kenya, to understand their approach to tree diversity and find out if this could be increased on their farms. Vihiga county is one of Kenya’s most densely populated areas, with a population of 590,013 people living on 531km² of land.
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Our research found that farmers were very interested in growing a wider variety of trees on their farms. But their decision-making was influenced by several factors, including their past experiences, other farmers’ opinions, and their relative wealth.
Targeted support, such as farmer-to-farmer knowledge exchange or providing farmers with direct financial incentives, could help scale up agroforestry in ways that benefit people and nature. Support from government extension services, non-governmental organisations and farmer cooperatives is particularly important. Simply planting monocultures (one species) of fast-growing trees won’t restore biodiversity or support local livelihoods.
Barriers to tree diversity
Many farms in Kenya are dominated by a few tree species alongside their main crops maize and beans – particularly fast-growing exotic tree species like Eucalyptus and Grevillea robusta. Farmers often choose these species because they grow quickly, providing fuel and timber.
But with most farms being less than an acre in size, every tree competes with space for food crops. One farmer told us that she would love to plant more trees for firewood and fruit, but worried that these would take up the space for her crops, which her livelihood depends on.
Our results also showed that some farmers feared that trees might have negative effects on their crops. This had been the case with eucalyptus, which can deplete soil nutrients and water. These experiences left some hesitant to experiment with new tree species.
Others worried that more trees would attract unwanted wildlife, particularly crop-raiding animals such as monkeys and rodents, and insects that could be pests. Farmers also spoke about the time and knowledge required to maintain trees properly. Agroforestry is not as simple as planting a seedling and waiting for it to grow. It requires careful selection of the right species, knowledge of how they interact with crops, and long-term management.
Making tree planting work for farmers and nature
Despite these barriers, our research also identified that farmers could be motivated to plant trees. Farmers who had previously planted trees, or had seen their peers do so, were more likely to increase the tree diversity on their farms. Peer-to-peer learning could be a valuable tool for increasing tree diversity in farming landscapes.
We also found that farmers with higher education levels (such as a diploma or university degree) and higher incomes were more inclined to experiment with tree planting. This could be because farmers with higher education levels may have greater awareness of agroforestry benefits and better access to training or extension services. This might make them more open to experimenting with diverse tree species.
Similarly, higher-income farmers might be able to more easily afford the upfront costs of tree planting. However, we also found that farmers who relied entirely on agriculture for their livelihoods were interested in expanding the variety of trees on their farms.
Designing tree-planting initiatives
Our research findings indicate that tree-planting initiatives should not be designed in a top-down manner. They must be tailored to local needs. These initiatives should address farmers’ worries, such as the risk of attracting wildlife or trees depleting scarce water supplies.
Governments could help by consulting farmers to find out what kinds of trees are useful for them before buying millions of seedlings. Locally run nurseries could make native species more accessible. Community-based training could equip farmers with the knowledge they need to integrate trees effectively. Without the right support, farmers remain trapped in a cycle of soil degradation and declining yields.
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Initiatives like Diversity for Restoration (D4R) and My Farm Trees are already taking steps in this direction. These programmes support farmers by providing diverse tree seedlings, offering training, and using digital tools to track tree growth. If there were more projects such as these, that would help ensure that tree planting supports biodiversity, restores landscapes, and sustains the livelihoods of those who depend on them.
For tree planting initiatives to truly benefit people and nature, they must be designed with farmers at the centre – not just as recipients, but as guardians and active decision-makers shaping the future of their landscapes.
Ennia Bosshard receives funding from the Alliance of Bioversity and CIAT for her PhD research at the University of Exeter.
This article was originally published on The Conversation. Read the original article.
