Agroforestry

The concept of sustainable development is based on the wise use of five forms of capital – human, social, natural, environmental and financial. The term ‘profit’ is generally applied only to the benefits derived from financial capital, but in fact is equally applicable to all five forms of capital. Here we consider how trees can deliver all these different types of profit.

Trees are typically under-recognized in society. Although generally seen as attractive features of our woodlands and landscapes, and as a source of wood, they appear to be static and omnipresent. This means they’re often seen as something of little value, or even as a hinderance to progress. In reality, they are keystones in ecological systems teeming with life and performing environmental functions crucial to both us and our planet.

A tree creates a 3D layer over the landscape (both above and below-ground) which provides niches to be colonized by millions of organisms of hundreds of different species from the smallest microbe to the biggest mammal. These organisms have intertwined lifecycles and food chains that regulate crucial processes like the nutrient, carbon and water cycles in the soil and the atmosphere. These interactions also regulate the ecological balance between desirable and undesirable species.

Trees also produce an incredibly wide range of products and we, as the apex predator and top herbivore, have grossly mismanaged our consumption and use of these products. We have not been living with nature – indeed much of our lifestyles has worked against nature – making us the top polluter and environmental vandal. We must therefore acknowledge that we have failed miserably in our prime role at the top of ecological systems, falling far short of our responsibilities. Indeed, we haven’t even looked after our own species! – and, as a result, have a divided and dysfunctional world in which modern farming and the clearance of trees is a major cause of the failures of tropical agriculture to both adequately feed and support the lives of billions of people.

How agroforestry can help to create a better world

Trees deliver environmental services and supply of thousands of useful products. Establishing a wide array of useful and beneficial trees in degraded farming systems could provide a pathway to a better life, freeing subsistence farmers from abject poverty, hunger and malnutrition. This is the basis of the concept of ‘agroforestry’ which has been developed over the last 40 years and is especially important in the tropics and sub-tropics where mechanical farm operations are not common practice.

There are an infinite number of ways to integrate trees into farming systems in different configurations, mixtures and densities. These create a wide array of landscape mosaics delivering a wide range of environmental, social and economic benefits, or ‘profits’. The following basic principles apply:

1. Harnessing environmental benefits

A mature tree regulates the environment and microclimate below the canopy and within the soils. By creating numerous niches for colonizing microbes, invertebrates, insects, amphibians, reptiles, birds and mammals, soils are enriched and restored to ecological health, with beneficial impacts on soil structure, water holding capacity and organic matter content. Additionally, through their life cycles and food chains, these organisms also perform the balancing trick that regulates the populations of injurious and beneficial species. Early in this succession it is the restoration of highly vulnerable soil microbe populations that is especially important as they ‘kick start’ many of the vital processes healthy and functional ecosystems rely upon. As we will see later, all this is also important for wildlife threatened by habitat loss.

In the context of the above, agroforestry practices aimed at rapidly restoring the fertility and health of seriously degraded soils by planting tree/shrub species of the pea/bean family (Leguminosae – colonized by nitrogenfixing bacteria) can increase crop yields by two to four fold. In parallel with promoting these soil bacteria, beneficial fungi colonize plant roots, sending filaments out into the soil, helping plants to scavenge for other nutrients. Unfortunately, however, a natural solution to the restoration of phosphate, potassium and trace elements soil deficiencies is not possible, so we need to generate income from these farms to enable the farmers to purchase inorganic fertilizers. The wide range of marketable tree products from agroforestry trees have the potential to be a huge source of this locally available income.

2. Capturing the benefits from tree products

Throughout the world there are tree species whose products have been used and/or consumed by hunter-gatherers to meet their day-to-day needs. Many of these products are highly nutritious and culturally important foods and medicines which typically are marketed locally and informally. Some 20,000 species produce edible products and to date agriculture and horticulture has only domesticated a few hundred of these – leaving enormous opportunity to cultivate others. Over the last 25 years, agroforestry research has encouraged smallholder farming communities to start domesticating some 50 of these species by selecting elite individual trees with high quality characteristics.

Elite trees can be identified and then multiplied up in the homestead using simple and well known horticultural techniques, that do not require piped water or electricity. The benefit flows from all this on-farm crop domestication provide incentives for farmers to engage and adopt these initiatives. This grassroots approach to crop domestication has been called ‘Social Modification’ to distinguish it from the high-tech laboratory approach of Genetic Modification.

As with domestication, a start has been made to add-value to these products by processing them locally for wider and year-round trade. This is being done in ways that benefit the farmers by recognizing their rights over traditional knowledge. Further work is, however, needed to protect their intellectual property. This develops the local economy in ways that generates income for the farmers allowing them to buy essential inputs such as artificial fertilizers. It creates new local businesses and employment, which in turn stimulates trade and improves the livelihoods in both rural and urban populations. This provides the foundation for long-term benefits for education, health and poverty alleviation, resulting in nationally-important new local industries that are not vulnerable to unscrupulous export/import regimes.

Outcomes and Potential Impacts

When the short-term and local impacts described above are aggregated through the scaling-up and geographical expansion of projects, it becomes clear that, if promoted by national and international policies and adopted by Development Agencies and Donors, they would address many of the Issues targeted by the Sustainable Development Goals. For example, by rehabilitating soils and agroecosystems, degraded farmland can again become highly productive and so able to feed the rural population. This removes the need to clear existing forests and establishes trees in farmland that both recreate wildlife habitat and sequester greenhouse gases in the woody biomass and soil carbon, so mitigating climate change.

As private property, agroforests are much less vulnerable to renewed clearance than publicly or nationally owned natural forests. They therefore deliver a very practical and sustainable option for the reduction of greenhouse gases, and the other benefits discussed above.

Furthermore, increasing the tree-based benefit flows from human and social capital has potential to mitigate the social injustice that lies behind the rise in illegal migration and indeed in social conflict at the national and regional level. Already, at the national level there is evidence that agroforestry based on domesticated indigenous trees leads to rural youths seeing a brighter future in their villages rather than being drawn to urban areas to seek employment. Further extrapolation therefore suggests that all of the above benefits from trees are a plausible path to planetary health and social justice at a global level.

How can we ensure an increased flow of benefits from trees?

Sadly, the capacity of trees to deliver multiple benefits is not well recognized by policy makers and development agencies. Here we have seen that planting trees in agroforestry systems can indeed deliver a complete package of ‘profits’ from natural, social, environmental, human and financial capital. Combined, these maximize the outcomes for wildlife and the planet, as well as engendering food and nutritional security, poverty alleviation, social justice and peace in local human populations. One key remaining challenge is, however, the gaining of recognition from policy and development agencies of the capacity of trees to deliver these multiple benefits.

We live in a divided and dysfunctional world of ‘haves’ and ‘have nots’, but trees in agroforestry systems can bring about positive change. Maximizing the five profits from trees, therefore, could free subsistence farmers from abject poverty and from subjugation by the social injustices that flow from failing agricultural policies.

Prof. Roger Leakey is a crop physiologist /tree biologist who has worked in forestry and agroforestry aimed at helping to reverse deforestation and desertification in the tropics.