Back to the forest

Commentary, Online Exclusive Feature / 1st Quarter 2020

Back to the forest

by Heather Banerd

A case for urban agroforestry

We often think of agriculture as separate from nature, a highly controlled system created to produce the most food at the lowest cost. A forest appears to be the polar opposite of this, a space protected from human intervention where nature can run wild. Yet, increasing evidence shows that many of the forests we think of as pristine have actually been cultivated by humans for millions of years. From the Amazon to North America and Southeast Asia, humans have practiced what we call today agroforestry, to favour plants that are edible or otherwise useful. As we look for alternatives to the unsustainable global food system, a return to agroforestry, or the creation of food forests, should be considered as an element of food resilience and an opportunity for sustainable food production, especially within cities (Levis, et al., 2018).

Layers of a food forest

There are seven tiers to a food forest. The tallest tier is the canopy trees, often fruit or nut species that need the most sunlight and will shelter but not shade the plants beneath. The second tier is the understory tree layer, where dwarf fruit or nut trees, or income-generating species such as coffee, rubber or olives can be grown. The third tier is the shrub or brush layer, where berries or other fruit bushes are ideal. This tier may occupy the same space as the understory layer. In the fourth tier, herbs, greens and other leafy produce make up the herbaceous layer, growing as smaller shrubs closer to the ground. The fifth tier is ground cover, spreading plants that keep the soil protected to retain water and nutrients. The rhizosphere, or root layer, forms the sixth tier, where root crops grow below the surface of the soil. Lastly, the vine layer, the seventh tier, occupies the same vertical space as the canopy and understory trees, using them as structural support to reach the sunlight.

Why agroforestry?

Our food system is broken. Most of the food we eat travels extreme distances before it reaches our plates; we can eat French cheese, Chinese bok choy and Mexican chia seeds all at once, in a café in Vietnam, Australia, or anywhere else we choose to dine at. Most of the nutrients in our food have been bred out or lost through poor growing conditions, with more lost in transit. Crops grown in monocultures are vulnerable to pests and diseases, so pesticides and herbicides pollute the air and water as well as linger on our produce; monocultures also leach nutrients from the soil, so fertilisers are added to help the crops grow. As climatic conditions shift due to climate change, this will not be enough—many crops will not be viable in the places they currently grow in. We know something needs to change, and urban farming is often presented as a solution to many of these issues. It sounds logical—moving production into cities, closer to consumers, would cut down on the carbon footprint of our food and reduce nutrient loss from travel. And yet, we should also look critically at of some of the large-scale systems proposed. Hydroponics, aeroponics and LED farming are all still monocultures; they depend on nutrient input, constant maintenance and can be energy-intensive (LED farming in particular). Are these systems so different from the conventional farms we have today, or are they simply the same system wrapped in a shiny new packing?

Agroforestry—a literal hybrid of agriculture and forestry, or more simply, ‘farming with trees’—is an alternative that takes a fundamentally different approach to food production. At the most basic level, it means cultivating edible plants within existing forests, but it can also mean introducing multi-tiered plant cover, particularly tree cover, to agricultural land (such as rice paddies), or using permaculture practices to create a diverse, multi-tiered productive garden that mimics the ecosystem services of a forest. Collectively, these are often called ‘food forests’.

A food forest is a closed-loop system; it does not require fertilisers, or pesticides, or much management of any kind, so the quality of produce is often better than a highly managed system. It is more resilient to climate change and extreme weather than monocultures. Ecosystems services reduce soil erosion and runoff, increase rainwater infiltration and regulate climate, but the diversity of planting also enables farmers to gradually transition to more suitable species if climatic conditions change. A forest will also be largely self-sustaining once established. In the province of Ha Tinh, south of Hanoi, is a renowned residential food forest. Sitting on just two acres of land, the forest has been managed by the same family for 28 generations and requires only minimal maintenance from the owners (Lawton, 2008), while producing nearly everything the residents need in their daily life.

Food forests also increase tree cover—there is no need to raze forests to plant crops—and support biodiversity. In Sumatra, rubber forests that were cleared and cultivated in the 20th century have become biodiversity hotspots (Mongabay, 2005), and food forests often retain diverse strains of plants that are not suited to monoculture farming. The owners of the Ha Tinh food forest often receive requests for seeds and cuttings from rare species in their forest. This helps to ensure long-term food security, as crops become more resilient to pests and diseases. It is also an opportunity to try growing wild species of edible plants, many of which are more nutrient-rich than even the plants we consider to be ‘superfoods’ (Robinson, 2013).

In rural areas, food forests are an important source of economic stability for farmers, who in return help to care for the forests. In Indonesia, agroforestry produces 80 per cent of rubber latex, 95 per cent of fruits and nuts, and  60–75 per cent of tree spices (clove, nutmeg and cinnamon), as well as bamboo, rattan, fuel wood and medicinal plants (Mongabay, 2005). In Northern Vietnam, where monocultural farming is practiced, researchers for the World Agroforestry Centre (ICRAF) found that issues of soil erosion, landslides and nutrient loss created huge vulnerabilities for farming communities. The ICRAF partnered with the Australian Centre for Agricultural Research (ACAR) and local partners to study the economic and environmental impact of agroforestry through a trial programme. This was such a success that other farmers in the area started their own food forests, and three neighbouring provincial governments each began development of a 50-hectare food forest in their province (CGIAR, 2016).

Where should we grow these food forests?

Rural and peri-urban spaces seem to be natural locations for food forests, yet there are real opportunities to integrate production into urban areas, specifically urban forests, nature reserves, public parks and interstitial spaces. Cities across Asia are working to increase their green cover and forest area in response to climate change. Hong Kong has achieved a green cover ratio of 40 per cent thanks to the lush parks and forests surrounding the city. Singapore has managed to increase its green cover ratio of 47 per cent despite urban expansion; Hanoi has set the ambitious task of setting aside 70 per cent of the city for trees and water by 2050; Shanghai is estimated to have doubled its green cover between 2000 and 2008 and is in the midst of developing an extensive green network connecting its parks and waterways (Siemens AG, 2011). All of these spaces have the potential to be more than just a public space and green cover, they could become productive landscapes as well. The new cities of China, in particular, open up great possibilities. Italian architect Stefano Boeri has famously proposed to tackle China’s air pollution crisis with ‘Forest Cities’ (Phillips, 2017), from lush green skyscrapers in Nanjing to a completely new forested masterplan for the city of Shijiazhuang in Hebei province. The Shijiazhuang master plan has green roofs and vertical planting, but it also has large areas set aside for recreational parks along the Hutuo River, and other areas for ‘basic farmland’ (Stefano Boeri Architetti, 2015). Recreational areas of the forest may allow public access, while productive areas could be centrally managed or leased to farmers for cultivation. Forest cover would increase without loss of productive land; crops would be of a higher quality and less vulnerable to pests and harsh weather; residents of all incomes would have access to fresh, local produce.

Policy challenges

Implementing agroforestry strategies at an urban level presents interesting policy challenges. Even in rural areas where food forests have been cultivated for centuries, farmers often have no rights over the land they are cultivating. As most countries do not have a classification for cultivated forests, they are registered as natural forests and are typically state land (Mongabay, 2005). Cultivation may be technically illegal, giving farmers no land rights if the government chooses to sell the forest to a developer. In an urban context, while the land rights and use may have more oversight, farmers are not necessarily deterred. The practice of guerrilla gardening—illegally planting interstitial spaces in cities such as urban verges, and the empty spaces underneath flyovers—is not common in Asia, but in cities where land is scarce and regulations are loose, or loosely enforced, it can be an effective way to optimise land use and increase green cover, inch by inch.

Questions of public access and foraging rights can also arise. In cities such as Singapore, where foraging and even picking up fallen fruit from the ground are banned (Ng, 2018), access to areas of production may need to be restricted, or the laws revisited. However, food forests need not be continually harvested or even made publicly accessible; where the purpose is food security, it should be enough to simply establish and maintain edible species. In the event that primary food sources are compromised, a food forest can become a fall-back supply of edible plants. However, there is also an argument to be made for allowing public access to food forests. High quality produce often comes at an equally high price tag, which makes it a luxury item restricted to only those who can afford it. Integrating productive landscapes into public parks and urban verges democratises high quality food. Anyone can walk through the park and pick some fresh fruit or vegetables.

Finally, the simple issue of coordination can raise hurdles for potential food forest farmers. Forestry and agriculture are often managed as separate entities; very few countries recognise the potential overlap between these spheres or have created policies to manage it (Borelli, Conigliaro, Quaglia, & Salbitano, 2017). With food security being a rising concern in many cities, this must be one of the first policy frontiers to be explored.

Looking to the future

Urban farming used to be a radical concept, but today, it is almost de rigueur for any new project. As yet, the concept of food forests as an innovative approach to food production rather than an ancient tradition has not taken hold in Asia. Countries such as the United States, Italy and Australia (Pyzyk, 2019) have seen a surge of interest in recent years, but they remain a niche field, and are still rarely seen in urban areas. Urban food forests may seem daunting now, but the multitude of benefits they bring should put them at the forefront of the food security conversation. If planners, architects and landscape architects are willing to recognise the potential of this approach, we could see a revolution in urban landscaping and a transformation in our relationship with food.

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