Why tree diversity in agroforestry matters: perspectives from the Comoros archipelago

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FTA communications

Originally posted by World Agroforestry 

The island of Anjouan in the Comoros has experienced one of the highest deforestation rates in the world. In the last two decades, 80% of its natural forests have disappeared. This was mainly due to agricultural pressure and excessive timber extraction, which triggered a negative spiral of natural resource degradation and poverty that put present and future livelihoods at risk.

Agroforestry is widely recommended as a pathway to restoring degraded landscapes through sustainable agriculture. However, different environmental and social benefits come from different tree species and management practices in different landscape niches. Researchers from World Agroforestry (ICRAF) explored the indigenous knowledge of smallholder farmers around Moya forest to assess opportunities and constraints in the development of agroforestry practices. Their results provided a basis for developing menus of tree options suitable for different farmers in different socio-ecological conditions.

Combining local and scientific knowledge in designing restoration options

The project team used a co-learning approach that builds on multiple knowledge systems and stakeholder engagement to design diverse and inclusive agroforestry options that match different conditions across the island and ensure continued provision of a range of ecosystem services.

‘Co-learning is important, not only because it ensures that options are appropriate to local situations, but it also confers strong local ownership of the options necessary for people to have confidence in adopting them,’ noted Fergus Sinclair, Agroforestry Systems Theme Leader at ICRAF.

The study conducted on local knowledge revealed that all farmers were actively managing trees on their land, with live fences of exotic leguminous species the most common agroforestry practice around the Moya forest. Terrace contour planting was rare even on steep slopes, as were riparian buffers, suggesting that additional effort should be put into promoting suitable practices for these specific landscape niches. There was more native tree diversity in the forest understory cultivation systems in the highlands, though the tendency was for a gradual shift towards more managed systems with clove trees, which farmers recognized were posing a threat to water regulation previously provided by forest vegetation.

Detailed and useful information was collated on 30 species commonly managed across the landscape, five of which are endemic. This was then combined with scientific and technical knowledge to develop decision-support tools for the promotion of agroforestry in the archipelago.

‘Anjouan is a volcanic island with striking topographic and socio-ecological variations. It is important that a diversity of tree species and management is promoted to cater for different farmers’ contexts and needs,’ revealed Emilie Smith Dumont, the project’s agroforestry scientist.

How agroforestry could contribute to biodiversity conservation in Anjouan

Tackle the water crisis

Deforestation is known to have a profound impact on watershed functions, and in Anjouan the situation is catastrophic: 40 of the 50 rivers that flowed permanently four decades ago have now become intermittent, causing severe water scarcity problems. According to Misbahou Mohamed, Technical Director at Dahari, a Comorian NGO, protecting native tree species and promoting sustainable land-use planning around springs and headwaters is key to restoring watershed functions. Drawing from their experience, farmers demonstrated detailed knowledge about how different species affect the water cycles, suggesting an array of priority species for reforestation around headwaters and springs.

Restore habitats and protect unique biodiversity

The island of Anjouan forms part of the Madagascar and Indian Ocean biodiversity hotspot. Forest habitat loss on the island threatens over 30 forest-dependent endemic species, including the flagship Livingstone’s fruit bat, that is now Critically Endangered. Several native and endemic trees like Ficus esperata, Nuxia pseudodentatata, Gyrostipula comoriensis and Ocotea comoriensis are roosting sites for the fruit bats. Thus, increasing the presence of these tree species in appropriate locations is of particular importance for biodiversity conservation.

Protect and enrich the soil

On hillsides or stream slopes, protecting the soil from erosion and enriching it is critical for sustainable agricultural productivity. Root and crown structures determine the ability of different trees to slow down run-off and hold soil in place, while leaf litter quality and the ability to fix nitrogen also determine how different species can contribute to soil fertility. In general, farmers preferred integrating tree species that produce a lot of leaf litter such as the exotic Gliricidia sepium. They also mentioned a wide range of native trees such as various Ficus species, Weinmannia comoriensisC. gorungosanum and A. theiformis. However, in “padzas”, a local name for heavily eroded barren land, rehabilitation will first require pioneer species able to restore soil health.

Diversify income and support livelihood needs

One of the key reasons that farmers are interested in trees is the economic opportunities that may come from the sale of products like fruit, timber and fodder. They were particularly keen on high-value tree crops such as ylang-ylang and clove. Given the historical fluctuation in export prices and market flows, ensuring that farmers can grow and benefit from a diverse portfolio of cash crops is critical to making livelihoods more resilient. This not only includes integrating shade-tolerant crops such as vanilla and pepper, but also a range of multi-purpose trees that can provide fruit, timber and firewood, as well as other environmental services.

Provide crop, livestock and tree fodder

In Anjouan, where population pressure is particularly high and livestock management extensive, farmers rely on mixed farming systems. Central to these is a tethered cow, used in soil fertility management by strategically rotating it across different plots. Fallow and grazing land have disappeared, and so a huge amount of time and resources is devoted (on average three and a half hours each day) to cutting and carrying fodder. In addition to Gliricidia sepium and Pterocarpus indica, introduced several decades ago and widely adopted as live fences, farmers also value a range of other species like the native Ficus lutea to provide a good supply of nutritious fodder during the dry season when fodder from other sources is scarce.

Moving forward: addressing barriers to scaling up agroforestry

The tree selection and management support tools have been tested and training will be scaled out to the different intervention sites in Anjouan in the coming months. This will help rural and environmental advisors and groups of farmers better tailor agroforestry options and tree-planting programs to their needs. ICRAF and Dahari’s research outputs, coupled with training on the propagation of native species, have made a significant contribution to filling key technical knowledge gaps.

Misbahou Mohammed (Dahari) and Subira Bonhomme (ICRAF consultant) testing the participatory tree scoring survey in Anteniju, Anjouan, Comoros. Photo: World Agroforestry/ Emilie Smith Dumont

However, a number of bottlenecks are likely to slow down the uptake of agroforestry practices across the islands. According to the National Project Coordinator, Mamou Oulda Abdallah, of the Ministry of Agriculture, Fisheries and the Environment, there are significant legal barriers that need to be addressed to successfully promote agroforestry in the Comoros. This includes revising outdated texts in terms of forestry and environmental legislation, as well as clarifying aspects of pluralistic legislation between customary, Islamic and national laws regarding tenure and inheritance. Other areas that require attention include improvements in tree crop value chains, technical support for the diversification of farming practices, and stronger coordination and cross-sectoral integration between agriculture, environmental, rural development and business initiatives.

Tools and manuals have been developed and will be launched, in partnership with the Ministry, at a forest landscape restoration workshop to be held in Moroni in early 2020. “This event aims to kickstart the adoption and spread of context-adapted agroforestry practices throughout the Comoros, to develop resilient, multifunctional landscapes that work for people and the environment,” noted Hugh Doulton, founding director of Dahari,


Acknowledgements: This blog and the research it refers to was funded as part of the Food and Agriculture Organization of the United Nations (FAO) project, “Elaboration of a national agroforestry strategy for the Comoro Islands” and the Darwin Initiative project, “Landscape approach to enhance biodiversity and livelihood resilience in the Comoros”, implemented in partnership with the Comorian NGO, Dahari. It is part of the CGIAR Research Program on Forests, Trees and Agroforestry (FTA).


Further reading


World Agroforestry (ICRAF) is a centre of scientific and development excellence that harnesses the benefits of trees for people and the environment. Knowledge produced by ICRAF enables governments, development agencies and farmers to utilize the power of trees to make farming and livelihoods more environmentally, socially and economically sustainable at multiple scales.

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