Food system impacts on biodiversity loss

Three levers for food system transformation in support of nature

Research paper Updated 29 March 2021 Published 3 February 2021 ISBN: 978 1 78413 433 4

Image of farmer in field in Cotabato Province, the Philippines

Professor Tim Benton

Distinguished Fellow, Environment and Society Centre

Carling Bieg

PhD candidate, University of Guelph

Dr Helen Harwatt

Senior Research Fellow, Environment and Society Centre

Roshan Pudasaini

PhD student and Arrell Food Institute Scholar, University of Guelph

Laura Wellesley

Senior Research Fellow, Environment and Society Centre

This paper explores the role of the global food system as the principal driver of accelerating biodiversity loss. It explains how food production is degrading or destroying natural habitats and contributing to species extinction. The paper outlines the challenges and trade-offs involved in redesigning food systems to restore biodiversity and/or prevent further biodiversity loss, and presents recommendations for action.

The paper introduces three ‘levers’ for reducing pressures on land and creating a more sustainable food system. The first is to change dietary patterns to reduce food demand and encourage more plant-based diets. The second is to protect and set aside land for nature, whether through re-establishing native ecosystems on spared farmland or integrating pockets of natural habitat into farmland. The third is to shift to more sustainable farming. All three levers will be needed for food system redesign to succeed.

Our recommendations for action are based around a series of major summits and conferences on food systems, climate, biological diversity, nutrition and related areas scheduled in 2021. These offer a unique opportunity for a ‘food systems approach’ to become embedded in international policy processes.

05 Technical annex

In this annex, we discuss in depth the principal channels through which food systems impact biodiversity, and review the existing literature. The annex focuses on terrestrial biodiversity, as affected by the terrestrial parts of the food system.115 We also consider the key approaches outlined in the literature to implementing dietary change, land-sparing for nature, and nature-friendly farming. These are the three levers for food system reform outlined in the main body of the research paper.

5.1 The impacts of today’s food system on biodiversity

As discussed in Chapter 2, the global food system today is shaped by a predominant ‘cheaper food’ paradigm. Under this paradigm, policies and economic incentives have been shaped over decades to deliver two key outcomes: greater quantities of food, and food at lower prices. Key to this paradigm has been the intensification of agriculture.

Since the 1960s, global agricultural output has risen enormously: calorie production rose 2.7-fold between 1961 and 2005.116 This increase was not achieved through agricultural expansion: over the same period, the area of land used for agriculture increased by only 10 per cent worldwide (see Figure 6).117 Instead, it was achieved through the intensification of agriculture: producing more food per hectare of land. Intensification has in turn been delivered through multiple practices, including breeding new varieties of crop for increased yield; increasing the density of plants in crops; increasing the confinement or stocking density of farmed animals; farming at greater scales; making more use of mechanization; irrigating the soil; and ramping up the use of inputs such as fertilizer, pesticides, growth promotors, soil-liming, and concentrated nutrition and antimicrobials for farmed animals. As can be seen in Figure 6, fertilizer use increased more than fivefold between 1961 and 2018, while pesticide use has almost doubled since 1990.

Figure 6. Trends in world agriculture

— Source: Food and Agriculture Organization of the United Nations (2018), FAOSTAT, www.fao.org/faostat/en/#data/OA (accessed 1 Dec. 2020).

Agricultural intensification has supported remarkable yield growth, but has come with significant environmental costs, as outlined in Chapter 2. These costs include huge losses in biodiversity. Globally, the number of species and abundance of organisms found at any given locality are estimated to have declined by about 14 per cent on average over the last 200 years. In sites associated with high land-use intensity, the number of species has declined by nearly three-quarters over the same period.118 Much of this is directly due to habitat destruction for food production. From 2001 to 2015, 27 per cent of deforestation globally was associated with the expansion of the production of commodities (such as beef, soy and palm oil).119 In the Amazon, between 1978 and 2020, more than 75 million hectares of rainforest were felled (equivalent to 1.5 times the land area of Spain); of this, about three-quarters was for cattle ranching.120 Habitat and biodiversity losses are occurring not only in forested regions, but across large areas of other types of land that are being degraded through agriculture around the world.

Below, we summarize the existing literature on the impact channels through which food production has driven biodiversity loss.

5.1.1 Impacts at farm scale

5.1.1.1 Homogenization of farmland

The incentives that drive farming productivity are the same as those that create specialization. The advent of herbicides and synthetic fertilizers in the second half of the 20th century reduced the requirement for complex crop rotations that suppress weeds and build fertility. Without rotations, there is no longer a need for separate field parcels. As a result, fields have typically been amalgamated into larger blocks of land for monocultures. Given the ability to manage land at scale with large machinery and equipment, these processes have led to increased homogeneity between fields (with adjoining fields often put to the same use) and over time (with simpler rotations, and large equipment). In effect, large blocks of land have come to be managed in the same way simultaneously.121

The fact that fields are typically sown and harvested at similar times means that the landscape is uniform both spatially and temporally. Many animals require different sorts of habitat at different times of the day or year (e.g. nesting habitat that is near foraging habitat), so spatial uniformity is problematic. Take, for example, European skylarks, which are ground-nesting birds that nest on farmland and require short vegetation for an unobstructed view of potential predators. Like many small birds, European skylarks need to rear multiple broods each year to maintain viable populations. Historically, after nesting once, they would have found another field nearby, planted with a different crop at a different time, where vegetation would have been short enough to allow a second brood to be reared. However, today it is likely that all nearby fields would be growing the same crop, planted at the same time, greatly reducing the birds’ ability to find a suitable breeding habitat.

As fields are amalgamated, non-cropped field boundaries and unused pockets of land are lost. Habitat that is not managed for production often has a diversity of native plants, and is utilized by animals for resting, reproduction and/or foraging. In studies of UK farmland, field margins are consistently found to house greater biodiversity than field edges or centres – up to three times the numbers of species and individual organisms.122 Plant biodiversity is greatest outside managed fields in unmanaged, uncropped, ungrazed areas. Non-farmed margins create habitat, supporting animal populations that spread into managed areas as the seasons progress. These populations include important pest-control species such as spiders and ground beetles.123 The diversity of animals and plants depends on a range of management practices, including sowing dates and pesticide usage.124 Furthermore, poor management of these marginal areas (e.g. the application of fertilizer and pesticides that seep on to uncropped land) can reduce their value both as habitat for animals and plants and as foraging areas for birds. The yellowhammer, a bird which, in the UK, nests in field margins, prefers to feed its chicks on insects caught in field margins. If this food source is unavailable, it will use unripe grains from crop fields as a substitute; however, such grains have lower nutritional quality, resulting in less robust chicks.125

5.1.1.2 Disruption of ecological communities above and below ground

Intensive agricultural practices have adverse effects on above- and below-ground ecological communities. Heavy tillage, monocropping and excessive use of agrochemicals destroy beneficial fungal and bacterial populations that help plants with nutrient availability and disease management.126 Entire soil microbial communities, which include thousands of beneficial microbes, are being simplified under intensive farming practices. They are losing the diversity they exhibit under organic or less intensive farming practices. This ultimately has negative implications for crop performance and yields.127 Above-ground biodiversity is also affected by the use of fertilizers and other inputs, such as pesticides. Fertilizer use on managed fields causes excess nutrients to ‘enrich’ natural neighbouring habitats, allowing more competitive grasses to grow and crowd out native, nutrient-limited ecological communities.128 In terms of other inputs, the use of pesticides (herbicides, insecticides, molluscicides, fungicides etc.) is harmful to non-target organisms both within cropping areas and through leakage into wider landscapes.129

Many insect populations have declined drastically in both terrestrial and aquatic ecosystems worldwide due to food production.130 The largest drivers of insect species decline, in descending order of importance, are as follows: 1) habitat loss, conversion to intensive agriculture and urbanization; 2) pollution, mainly from synthetic pesticides and fertilizers; 3) biological factors, including the presence of pathogens and introduced non-native species; and 4) climate change.131 If current trends continue, it is estimated that 40 per cent of insect species will become extinct within the next few decades, though not all species will be impacted equally. Specialist species are being replaced by pollution-tolerant dietary generalists.132 Many of these specialist species, which are vulnerable to land modification and pollution, play important functional roles in their ecosystems.133

For example, both spiders and ground beetles have been indicated as invertebrate taxa that are particularly affected by agricultural land use. Certain species are more heavily affected than others. However, researchers have found that such groups do not necessarily suffer strict declines in species richness but instead change in composition in response to different land uses.134 In addition to harming dietary specialists, agricultural land uses have severe impacts on many habitat specialists. Spiders, for example, are important predators in agro-ecosystems, but certain functional types of spiders rely on specific habitats. Among these are aerial web-building spiders, which are particularly dependent on riparian zones and hedgerows as habitat. As more of these areas are developed for food production, the functioning of whole agro-ecosystems may be impaired. That said, even small ‘habitat islands’ within arable croplands can support unique groups of ground-dwelling spiders and carabid beetles that would not be present in regular cropland.135 The type of habitat in these islands, rather than the islands’ size, mostly determines the diversity of species.136 This suggests that maintaining habitat heterogeneity – even in small quantities – is crucial for conserving biodiversity and ecosystem functionality in agricultural lands. Hence, habitat complexity on a local scale is important for maintaining specialist predator populations that are important for pest control.137

5.1.1.3 Pollution of aquatic ecosystems

Uncropped areas around drains, streams and rivers – riparian zones – also serve as important habitats that integrate communities of plants and animals from aquatic and terrestrial environments. Many terrestrial wildlife species that directly improve food production also rely on riparian zones. Such species include insects that develop in streams, emerge as adults into the air and feed a range of predators, including birds and spiders. In turn these predators, sustained by prey from non-cropped land, can control pests on farmed fields. Importantly, there is a feedback loop between terrestrial and aquatic ecosystems, as the degradation of aquatic ecosystems can negatively impact populations on land and vice versa. For example, the species richness and population density of spiders have been shown to be negatively correlated with pesticide toxicity in streams, which provide habitat for the emerging insects on which the spiders feed.138

Riparian zones are also important for reducing nutrient and pesticide run-off and soil erosion into adjacent streams, which can affect water quality and stream communities. At low levels of run-off, these nutrients may promote functioning and stability of communities; however, increasing nutrient flows downstream can rapidly destabilize food webs.139

5.1.1.4 Loss of large herbivores through grazing of farmed animals

Incentives to increase agricultural productivity and farm incomes in preference to preserving wildlife habitats are not limited to highly intensive agricultural systems. Land degradation caused by overgrazing from extensively farmed herbivores is particularly acute in some countries, as illustrated in the example in Box 6 on pastoralist/grazer/wildlife conflict in Botswana.

Box 6. Pastoralist/grazer/wildlife conflict in Botswana

Conservation of African wildlife is often dependent on the interaction between conservation areas and adjacent pastoral areas. With human population densities, the size and number of settlements, and grazing pressure of farmed animals in communally managed pastoral areas all increasing, there is the potential for grazing land to become degraded, putting pressure on conservation areas. A study in the Kalahari Desert in 2019 looked at the interactions between farmed animals and wildlife.140 The study showed that while pastoral activities were largely confined to communally managed grazing areas within about 15 km of the main settlements, the free-ranging farmed animals reduced forage quality and quantity in wet and dry seasons. Large wild herbivores and carnivores avoided the communally managed grazing areas. Medium-sized wild herbivores and carnivores avoided areas of high grazing intensity, but used moderately grazed areas outside the conservation areas. Small wild herbivores, except springbok, foraged across the communally managed grazing areas. These results suggest that, even though pastoral lands near conservation areas are important as seasonal dispersal and breeding grounds for wildlife, intensified pastoral activities (such as increased intensity of farmed animal grazing) and pastoralist-induced risk are restricting the seasonal movements of medium-sized to large wildlife between the conservation areas and the adjacent communal grazing areas.

5.1.2 Impacts at landscape scale

The discussion above has focused broadly on what farming does to wildlife at the field and farm scale – through immediate impacts from tillage, grazing, nutrients and other chemical inputs, and farm specialization. Looking at the issue at landscape scale allows analysis of the additional impacts that arise from larger, more uniform agriculture across multiple farms in a given setting. As discussed in the literature, the impact of an intensive farm in a landscape of semi-natural habitat is very different from the impact of the same farm in a landscape of uniform monoculture.141

5.1.2.1 Reduced landscape heterogeneity

Agricultural expansion and intensification have simplified once-complex landscapes, causing habitat loss and fragmentation and reducing biodiversity among plants, insects and animals.142 Decreasing landscape heterogeneity by switching to single crop production over large areas, as well as removing buffers between farms, depletes breeding habitats and important food sources for many different organisms (including birds, butterflies and spiders). Often, the lost or depleted habitats served as refugia for species, providing habitat ‘corridors’ that facilitated movements across a landscape. The ability to continue to move across landscapes in this way is increasingly important as climate change affects the areas over which species can range – necessitating, generally, a move towards the poles or higher altitudes. Additionally, large-scale intensive farming often removes or reduces numbers of generalist consumer and predator species important for maintaining the stability of ecosystems. Interactions between the remaining components of the simplified food web cause greater variation in species’ population sizes, leading to enhanced risks of local extinctions, further reducing the resilience of the overall system. As a result, we can see many other species declining in abundance or being extirpated from heavily farmed areas, and these regions becoming more susceptible to pest outbreaks as a consequence.143

5.1.2.2 Disruption of ecosystem services

Food production adversely affects a variety of taxa that play important functional roles in their ecosystems, including providing supporting ‘ecosystem services’ to agriculture. When agricultural yields increase as a result of more intensive farming, this in turn causes biodiversity losses that negatively affect the land’s yield potential (see Chapter 2 and Figure 3). For example, pollinators have suffered drastic declines in regions around the world, with intensive agricultural practices representing a major threat.144 Fertilizer use, intensive tillage, heavy use of pesticides, crop monocultures and high grazing/mowing intensity all dramatically reduce the size and diversity of pollinator communities – there is no single or simple relationship between a single practice and biodiversity decline.145

Locally, the species richness of pollinators declines with repeated pesticide application; but, importantly, these patterns are consistent across whole regions.146 In regions with more intensive pesticide applications, there is far lower species diversity of bumblebees and butterflies.147 Winged pollinators such as bees are capable of pollinating large areas of land, but actions such as pesticide use on one farm can have implications for entire regions. Moreover, despite many pollinators’ wide dispersal abilities, native habitats remain crucial for maintaining pollination on agricultural lands. Additionally, the simplification of habitats on a landscape scale causes mismatches between plant and pollinator functional and phylogenetic associations, suggesting the potential for large-scale changes to ecosystem functionality.148 Both pesticide use and isolation from natural habitats cause declines in visitation by flying pollinators, although even small patches of native flowers distributed across a landscape have been shown to mediate the effect of isolation, for example in large mango orchards in South Africa.149

Monocultures and pesticide use make whole regions more susceptible to pest outbreaks, further diminishing nature’s ability to provide a buffer against shocks. As discussed previously, invertebrates such as spiders and beetles, as well as insectivorous bird species, act as important predators for pest control. Declines in these ecological roles are happening due to local land use and modifications, although some research suggests that habitat heterogeneity on a landscape scale is even more important than local action for pest control.150 Even without crop rotations, habitat complexity across a landscape can significantly improve pest control by predators and parasitoids, and potentially by pollinators as well.151 This highlights the findings of Knapp and Řezáč.152 However, it also suggests that on-farm decisions may be insufficient to ensure the maintenance of important ecosystem functions if the whole landscape is not managed properly, given that the spatial scale of pest control depends on the natural predators present in agro-ecosystems and their dispersal abilities as well as their functional traits.153

Farming has been identified as potentially the largest threat to bird populations worldwide.154 A recent study showed that agriculture in Costa Rica has caused long-term changes to bird communities.155 Declines in all major guilds were seen, including birds important for pest control, pollination and seed dispersal. Furthermore, these structural shifts led to increases in community similarity and decreases in resilience to climatic events. These results were especially apparent in intensively farmed areas, suggesting that diversified agricultural land uses (i.e. those that maintain some natural land) could lessen the burden of agricultural development on biodiversity.

5.1.2.3 Nutrient pollution at catchment level

Pollution from excess nutrients washing off farmland – known as eutrophication – affects streams and pools adjacent to agricultural lands. The effects can be dispersed downstream into lakes and coastal zones, leading to toxic algal blooms and hypoxic dead zones.156 As rivers and streams are modified for faster drainage and lower maintenance (i.e. through channelization) and wetlands are developed into productive agricultural land, the natural capacity of ecosystems to deal with excess nutrients and chemicals is being lost. Natural land cover within agricultural catchments is becoming increasingly important as more land is developed and more fertilizers are applied to croplands. There is likely to be a threshold level of natural land cover (e.g. wetlands, woodlots and grasslands) in these catchments that is needed to buffer against increases in dissolved organic carbon and nutrients in streams associated with hydrological patterns (i.e. flood events). As estimated by Fasching et al.,157 the threshold of natural land cover is likely to be around 30–40 per cent, below which hydrological events can significantly increase nutrient run-off. Pesticides from farmland can also leach into nearby waterways and have negative impacts on aquatic communities both locally and downstream. Various chemicals, especially pesticides, affect the physiology of aquatic animals, increase chances of infections, hamper reproduction, and thus bring changes in the composition of whole ecosystems.158 Once again, these patterns highlight the importance of native landscape heterogeneity for maintaining ecosystem functioning and resilience.

5.1.3 Impacts at regional and global scale

The spatial spread of environmental impacts can occur in many ways: agriculture in one place influences biodiversity in others.159 The mechanisms can consist of physical effects (e.g. pollution carried by air or water) or biological effects (the enhancement, or depression, of populations in one location creating spillover effects as individuals move). The spread of environmental impacts is also a function of global GHG emissions from agriculture, which change the availability and quality of habitat worldwide. A final route for regional and global impacts is through markets: demand for food in one place can incentivize agricultural intensification or land-use conversion in other distant places.

5.1.3.1 Pollution of rivers and regional-scale impacts

Rivers and streams can be thought of as transport systems that connect ecosystems across a landscape. Nutrients and sediment from agricultural run-off can rapidly be carried long distances, particularly via waterways, and can accumulate and have drastic effects on the biodiversity and stability of distant ecosystems.160 The prevalence of waterway modifications such as damming and channelization, along with land-use changes for food production, means that nutrient and biological flows between ecosystems are being changed drastically. The magnitude of nutrient flows from urban and agricultural development into ecosystems is increasing. Moreover, the rates at which nutrients are carried between ecosystems are also increasing due to alterations to river and stream morphology.161

As well as acting as a transport network for pollutants or sediments, the aquatic environment constitutes a crucial habitat for significant biodiversity, and is sensitive to the amount of water as well as its quality. Irrigation, through abstracting water from groundwater flows, has the potential to reduce such flows to the extent that ecology is affected, in effect interrupting the minimum ‘environmental flow’ necessary to sustain a given ecosystem. Prolonged or frequent examples of low or zero groundwater flows can lead to significantly changed biodiversity.162 Currently, about 40 per cent of irrigation comes at the expense of environmental flows.163 Furthermore, water transfer schemes (designed to carry water from a place of excess to a place of need) can significantly alter local aquatic habitats, threatening their inherent biodiversity.164 Currently, less than one-fifth of the world’s pre-industrial freshwater wetlands remain; this proportion is projected to decline to under one-tenth by mid-century.165 Climate change, alongside growing demands for fresh water for direct human use and agriculture,166 is changing hydrological flows as well as the way in which nutrients are assimilated into ecosystems.167 This makes it even more important to consider the connectivity between ecosystems and the distant impacts of food production systems.

The link between agricultural run-off and downstream algal blooms and dead zones around the world is becoming increasingly clear. However, we are beginning to see that food production can have even more distant, and often unexpected, impacts on biodiversity and ecosystem stability.168 For example, Wang et al.169 recently found that deforestation and agricultural development in the Amazon River basin appear to be fuelling Sargassum seaweed blooms in the tropical Atlantic. The Amazon carries nutrients to the ocean, where currents circulate them, and massive blooms are formed where they accumulate. This results in a massive mat of dense seaweed that is no longer habitable for many species, and that washes ashore throughout the Caribbean and Gulf of Mexico, where it can cause further ecological and environmental problems. At their peak densities, these Sargassum blooms have been shown to stretch across the Atlantic, from the Caribbean to West Africa.170

5.1.3.2 Air pollution

Both synthetic fertilizers and manure can pollute the air with ammonia and nitrous oxide. Synthetic fertilizers are typically urea or ammonium nitrate. In wet soils, denitrifying bacteria break down nitrates into nitrogen oxides (NOx), leading to emissions of these GHGs. Fertilizers also release ammonium (NH₃), a process termed volatilization. On average, worldwide, 18 per cent of applied N fertilizer (and up to a maximum of 64 per cent) was lost as NH₃ up to 2016.171 Together, NOx and NH₃ help create secondary particulate matter (PM), which contributes to poor air quality and smog.

Poor air quality directly affects some biodiversity (for example, lichens are particularly sensitive to NOx), but the increased nitrogen in the atmosphere can also be deposited in rain, leading to nutrient enrichment that has effects similar to the eutrophication of water discussed above (excess nitrogen affects biodiversity through direct toxicity, soil acidification, nutrient imbalances and interspecific competition).172 Indeed, some authors have suggested that excess nitrogen deposition is the third-largest global threat to biodiversity after land-use change and climate change.173

The impact of pesticide drift through the air is not proportionate to the large scale at which nitrogen can be transported around the world. Nonetheless, particularly from aerial applications (by drones and planes), pesticides can drift up to 300 metres from the target.174 Clearly, this has the potential to affect non-target organisms and, in highly fragmented areas (where habitat patches are small), impact on species viability in a locality.

5.1.3.3 Changes to population processes

Biodiversity is a measure of what lives in a locality, and its genetic composition. However, biodiversity in a given locality can also depend on what is happening elsewhere. Many species migrate seasonally, so the persistence of a population in one place may depend on the conditions in another during a different season. For example, the migratory monarch butterfly (which travels between Mexico and northeast America) is declining in population size. A recent study examined the relative roles of three separate factors in this decline: (1) habitat loss in the monarch butterfly’s breeding grounds in northeast America; (2) habitat loss in its overwintering grounds in Mexico; and (3) extreme weather (driven by climate change). The authors concluded that ‘recent population declines stem from reduction in milkweed host plants in the United States that arise from increasing adoption of genetically modified crops and land-use change, not from climate change or degradation of forest habitats in Mexico’.175 In other words, agriculture in one place (in this case, displacing host plants on butterfly breeding grounds in the US) can lead to biodiversity decline in another place through population reduction of a migratory species (in this case, reduced breeding in the US results in fewer butterflies migrating to Mexico).

At the same time, biodiversity loss can arise from agriculture through enhancement of the populations of some species at the expense of others. The coastal Arctic wetlands – hundreds of kilometres away from any agricultural development – serve as breeding grounds for populations of migratory geese and have been completely transformed in recent decades.176 Due to increases in agricultural production in the US, where the geese overwinter, breeding populations have increased so much that they have radically altered their fragile breeding habitats: overgrazing and overfertilization have turned salt marshes into hypersaline mudflats, which may be a difficult state to recover from.177

Agricultural management can also boost populations of organisms that have negative impacts on local populations, through the introduction of pests and diseases that then spread from their introductory sites. One example is the prickly pear cactus (Opuntia ficus-indica), widely used for its fruit178 and also widely foraged, which is a highly invasive cactus that alters local ecosystems in many areas of the world.179

Attempts to control pests, whether plants or animals, through the introduction of predators have sometimes had unintended consequences. For example, in the mid-1930s cane toads were introduced in Australia to suppress a beetle pest of sugar cane. The cane toads have since spread, covering a large area of the country’s northeast coastal fringes. Cane toads directly affect local ecology by eating native plants and competing with native animals, and, because they are poisonous, kill their predators indirectly. This contributes to a cascade of impacts across trophic levels: large, anurophagous (toad-eating) snakes (which are apex predators) die, releasing ecological space that allows increases in mammal-eating meso-predatory snakes.180 Where cane toads are common, native mammals disappear.

It is not just terrestrial agriculture that has been responsible for such problems. Aquaculture also has a significant track record of perturbing biodiversity, through the introduction of alien species (both fish and feed plants) and pests (such as sea lice, which escape from salmon cages and affect the viability of local populations).181 Iconic examples of escapes/introductions include tilapia and Nile perch, which have subsequently altered ecosystems across the world via changes in competitive interactions. From a biodiversity perspective, perhaps the most impactful change has been the extinction cascade of species ‘swarms’ of endemic cichlids – perhaps over 500 species died out in Lake Victoria following the introduction of Nile perch.182

In aquaculture, another form of biodiversity impact occurs through genetic integration: where escaped farmed animals, with different genetic traits, breed with native ‘wild-type’ species, thereby potentially undermining the genetic integrity of native animals. In a recent study, significant rates of genetic integration were found, reducing the fitness of wild salmon in many rivers in Norway.183

Genetic pollution – gene introgression – can also occur from crop plants into wild populations. A recent study of rice, for example, showed that gene introgression altered the genetic structure of wild relatives of the crops in surrounding populations,184 creating a challenge wherever crop plants are grown in proximity to wild species with which they can breed. In this case, ‘proximity’ can mean quite large distances: maize pollen can be detected more than 4 km185 from the nearest maize fields, so the risks of gene introgression in natural populations are not merely about close exposure between genetically modified and wild plants.

5.1.3.4 Land-use change and teleconnections: market connectivity across space

Another way in which agriculture in one place can affect biodiversity in others is through market linkages, a process called ‘teleconnection’. The term is borrowed from climate science, where it is used to indicate when weather in different places is affected by the same underlying climatic cause. Teleconnections in food emerge from globalized supply chains, where food consumed in a given country is often a combination of local and overseas production. Imagine, for example, that a country decides to conserve its own biodiversity by making agricultural production more environmentally friendly. Moves towards wildlife-friendly farming (e.g. agro-ecological or organic farming) typically come with a cost to productivity as farming intensity is scaled down.186 If total demand for food in the focal country does not change, yet local agricultural production declines because of biodiversity-friendly farming, price signals will incentivize intensification (or ‘extensification’, i.e. expansion of land use) somewhere else, and demand will be filled through global trade. This potentially leads to a biodiversity saving in one place but a biodiversity cost in another.187 For example, in 2010 it was calculated that if the EU increased the amount of organic farmland to 20 per cent of all cropland, then overall agricultural yields would decline by an amount that would require more than 10 million hectares of land outside the EU to be used to support food consumption in the EU.188 This implies a biodiversity cost as agriculture is intensified or as previously unfarmed land is brought into production. The cost could be even higher if production occurs in places with both significantly higher intrinsic biodiversity than the EU and weaker biodiversity governance: the result would be an overall net negative impact on global biodiversity.

5.1.3.5 Climate change’s global impacts

The food system is a major source of global GHG emissions, contributing significantly to climate change. In its special report on climate change and land,189 the Intergovernmental Panel on Climate Change (IPCC) estimated that the food system contributes around 30 per cent of all anthropogenic emissions, when emissions associated with agriculture, land-use change for agriculture, and the processing and transporting of food are all taken into account. This figure is consistent with the most detailed compilation of life-cycle assessments associated with the food system.190

While land-use change, mostly driven by agriculture, has been the principal driver of biodiversity loss since pre-industrial times,191 the 2019 global assessment by the Intergovernmental Science-Policy Platform on Biodiversity and Ecosystem Services (IPBES) highlights the role of climate change as an increasingly important determinant of biodiversity:

[Climate change has] contributed to widespread impacts in many aspects of biodiversity, including species distribution, phenology, population dynamics, community structure and ecosystem function. According to observational evidence, the effects are accelerating in marine, terrestrial and freshwater ecosystems and are already impacting agriculture, aquaculture, fisheries and nature’s contributions to people. The compounding effects of drivers such as climate change, land-/sea-use change, overexploitation of resources, pollution and invasive alien species are likely to exacerbate the negative impacts on nature, as seen in different ecosystems including coral reefs, the Arctic systems and savannas.192

Climate change is altering habitat suitability throughout the world. As a first approximation, the area in which a species lives is determined both by the suitability of its physical habitat and by a climatic envelope (which may directly affect an organism’s ability to live there by, for example, exposing it to high temperatures; or indirectly affect an organism’s ability to live there by affecting its predators, parasites or food). As climate changes, the envelope of suitable climate is expected to move in several ways: (1) towards the poles for many organisms; (2) up an elevation gradient in mountainous areas; or (3) towards deeper waters for aquatic species.193 Species either move as the climate changes or they risk extinction as the weather changes in their historically suitable habitat. On average, for a variety of species of agricultural pests, the rate of movement over the past 50 years or so has been about 3 km per year.194

As a result of the need for species’ movements to track a changing climate, and the fact that different groups of species move at different rates,195 climate change is rewiring entire ecosystems.196 The result is increasing introductions and losses of species. At a theoretical level, this amounts to a series of perturbations that decrease a system’s resilience. For example, climate change makes aquatic systems more susceptible to nutrient-driven algal blooms and dead zones. It may also alter the phenology of plants/pollinators and change or restructure consumer–resource interactions (e.g. between insects and pollen) that are simultaneously affected by agriculture. Similarly, weather changes associated with climate change affect the linkages between whole ecosystems (for example, between fields, streams and lakes/oceans), with the transfer of nutrients from one place to the next particularly impacted. As highlighted in the IPBES quote above, all these climate change impacts will have compounding effects in conjunction with other major drivers of biodiversity loss associated with agriculture – such as land-use change and intensification of food production – and will thus act as threat multipliers.

5.1.3.6 Interactions with aquatic food production systems

Interconnections within the food system mean that many of the factors we discuss – including supply and demand drivers, pressures on the food system and ecological effects – are intertwined in numerous and complex ways. Actions targeted at one sector or place can have ripple effects on other sectors or places. For example, changes in demand for land-based and water-based food products affect each other: reducing the demand for animal products to improve terrestrial environmental outcomes might increase demand for fish protein, with negative marine environmental outcomes.197 Blanchard et al.198 discuss the difficulties of combining marine and terrestrial food production sectors and ecosystems within strategies for meeting the Sustainable Development Goals that are focused on food, biodiversity and climate change. However, they note that an effective formula is needed if progress is to be achieved in sustainably meeting increasing global demand for food and ensuring food security. There is a growing need to recognize the links and interdependencies between fisheries, aquaculture and the agricultural components of the global food system as more food is required and diets change. Similarly, there are feedbacks within this cycle. Some feedbacks may be obvious in terms of the ecological services both required for and degraded by food production, but feedbacks such as climate change may also have important long-term implications. The current food system is contributing significantly to global GHG emissions, and therefore to climate change. At the same time, the resilience of this system to shocks and impacts from climate change is being degraded. Some countries are likely to face increased uncertainties in both fisheries and agriculture due to climate change impacts, so it is important to ensure supply chains equitably distribute food around the world.199

5.2 Options for implementing food system redesign in support of biodiversity

As discussed in the main chapters of this paper, three broad levers exist for altering the relationship between food systems and biodiversity in favour of biodiversity. The first is to reduce the pressure on land by changing patterns in demand for food – including encouraging people to move to more plant-based diets. The second is to set aside land for nature, as unmanaged ecosystems are inherently more biodiverse than managed ecosystems. The third is to adopt more nature-friendly farming systems. The more the first option is taken up in the form of dietary change, the more scope there is for the second and third options.

5.2.1 Demand-side changes to relieve pressure on land

The potential for more sustainable diets to drive changes in agriculture has been highlighted in numerous analyses in the past years.200 The essence of the argument is that (a) on average we produce more food than we need per capita; that (b) different foods have different environmental footprints; and therefore that (c) if we all ate a diet consisting of the right amount of low-footprint food for a healthy diet (not wasting or overeating), it would significantly reduce total demand for food (notwithstanding the fact that some communities would need to eat more food to lead healthy lives). In theory, if the totality of food demand were reduced, it would significantly reduce the pressures on land, allowing more land to be protected for nature and/or the intensity of farming to be reduced.

In 2011, the UN Food and Agriculture Organization (FAO) published an influential report which stated: ‘Roughly one-third of the edible parts of food produced for human consumption gets lost or wasted globally, which is about 1.3 billion tons per year.’201 Since 2011, considerable effort around the world has been made to improve this statistic. So far, while countries and food systems vary, the figure of 20–30 per cent loss and wastage is taken as a reasonable consensus. A recent academic analysis concluded the following:

The results suggest that due to cumulative losses, the proportion of global agricultural dry biomass consumed as food is just 6% (9.0% for energy and 7.6% for protein), and 24.8% of harvest biomass (31.9% for energy and 27.8% for protein). The highest rates of loss are associated with livestock production, although the largest absolute losses of biomass occur prior to harvest. Losses of harvested crops were also found to be substantial, with 44.0% of crop dry matter (36.9% of energy and 50.1% of protein) lost prior to human consumption. If human overconsumption, defined as food consumption in excess of nutritional requirements, is included as an additional inefficiency, 48.4% of harvested crops were found to be lost (53.2% of energy and 42.3% of protein). Over-eating was found to be at least as large a contributor to food system losses as consumer food waste.202

Figure 7. Estimated global variation in GHG emissions, land use, terrestrial acidification, eutrophication and scarcity-weighted freshwater withdrawals, within and between 36 major foods

— Notes: (A) Protein-rich products. Grains are also shown here, given that they contribute 41 per cent of global protein intake, despite lower protein content. (B) Milks. (C) Starch-rich products. (D) Oils. (E) Vegetables. (F) Fruits. n = farm or regional inventories. Pctl. = percentile. Source: Poore and Nemecek (2018), ‘Reducing food’s environmental impacts through producers and consumers’.

In other words, reducing food waste, reducing the environmental footprint of diets and reducing overconsumption have, between them, the potential to reduce the pressure on land by a significant amount. Were populations to adopt local dietary guidelines (which are not based on optimizing diets for sustainability in most places), this alone would reduce GHG emissions and other environmental impacts by 29 per cent and 5–9 per cent, respectively.203 Reducing food loss and waste by 50 per cent could further reduce environmental pressures (in terms of GHG emissions, use of cropland, and use of water, nitrogen and phosphorus) by 16 per cent, taking into account the anticipated increase in food demand by 2050. Reducing food loss and waste by 75 per cent, meanwhile, could yield a 24 per cent decline in environmental pressures. If diets were optimized to minimize their environmental footprint, the pressure on cropland could be reduced by as much as half.204

The replacement of animal-sourced products, which now supply 18 per cent of calories consumed by humans,205 could significantly reduce the pressure on land from agriculture and contribute to environmental sustainability goals.206 Different agricultural products have different environmental footprints. The most comprehensive study today is by Poore and Nemecek207 (see Figure 7). As can be seen from the figure, producing 100 g of protein can require an average of 164 m2 of land for beef, but just 2.2 m2 of land for tofu: in other words, the land-use footprint for tofu is 1/75 that of beef. Similar variances apply to the carbon footprints of different protein sources, and to their respective pollution footprints (in terms of production contributing to the enrichment and acidification of water courses). Changing patterns of consumption from foods that have large environmental footprints to those that have smaller ones can be a potent way of reducing the land requirements and environmental impacts of food production.208

Changing diets and reducing waste have greater potential to reduce environmental footprints and pressure on land than do supply-side interventions.209 For example, substituting beans for beef in the US diet could free up an area of 692,918 km2 – equivalent to 42 per cent of US cropland – which could then potentially be used for ecological purposes.210 Furthermore, one aspect of demand-side change likely to be helpful to biodiversity would be to shift towards healthier diets, rich in fruit and vegetables, and away from ultra-processed diets dependent on calorie-dense crops and animal products. A greater range of crops, coupled with reduced demand for animal products, would potentially allow for more diverse and regenerative farming landscapes to be maintained. Such landscapes would not only reduce nutrient leakage but would also, owing to greater spatial heterogeneity, support greater biodiversity.211

Recent years have also seen innovation in the production of alternative proteins, including plant-based meat substitutes, ‘clean meat’ (animal meat produced via cellular agriculture in laboratories) and insect protein (in the form of processed insect meat). These products are already on the market, and companies and governments are seeking to scale up production and sales.212 In 2017 China, the biggest consumer of meat, made a $300 million deal to import clean meat from different companies in Israel as a part of a national mission to cut conventional meat consumption by 50 per cent.213 The global market for alternative protein is expected to grow at a compound annual rate of 9.5 per cent, by value, to $17.9 billion by 2025.214 As the alternative-meat concept is still in its infancy, further measurement is required to determine its exact implications for human health and environmental sustainability on a larger scale.215

5.2.2 Setting aside land for biodiversity

Agriculture requires changing ecosystems from their natural state into a managed state. As a basic approximation, the more the managed state differs from the natural ‘unmanaged’ state, the more yield can be produced but the less biodiversity-friendly a given farming system becomes. In other words, the more food the system must produce, the less suitable it becomes as habitat for wildlife.216 Thus, in terms of biodiversity conservation, the biggest gains will be made when whole ecosystems, particularly biodiverse ones such as tropical rainforests, are protected from land conversion (as discussed in the main chapters of this paper).

This argument is summed up by the following logic: broadly speaking, to produce a given amount of food, a large area of land can be used and farmed in a more wildlife-friendly way (but with smaller yields per area), or a smaller area of land can be used and the area farmed more intensively (with larger yields per area). This is the essence of the ‘land-sharing’ vs ‘land-sparing’217 debate, which seeks to understand how best to integrate the needs of wildlife alongside the use of land for agriculture.218

At a given spatial scale (globally, regionally or at a landscape scale), land use can essentially be approached in two distinct ways. On the one hand, land can be shared between wildlife and farming, with nature fully integrated within a given area of farmland. Under this arrangement, intensive farming practices (in terms of chemical inputs, scale of operations, etc.) are avoided, and field margins and small areas of uncropped land are left. Such systems are less productive in terms of food output, but more beneficial for on-farm biodiversity. The alternative potential approach – land-sparing – is not yet in widespread use as a purposefully designed policy, but theoretically involves separating rather than integrating the two types of land use. In other words, it involves dividing land between intensive agricultural areas (which produce larger yields from smaller areas) and areas spared for biodiversity conservation. Which strategy may be better depends in theory on three factors: (1) how much more beneficial natural ecosystems are for biodiversity relative to nature-friendly farming systems; (2) the degree to which spillover effects can be minimized; and (3) governance of the spared land (including its amount, type, location and protection).

Addressing the first point, a large number of studies have now shown that in principle land-sparing can be more effective for biodiversity conservation.219 For example, in the UK a study comparing ‘land-sharing landscapes’ (rich in organic farming) and ‘land-sparing landscapes’ (intensive farms plus land set aside into wildlife areas) found that, most of the time, the land-sparing landscapes should provide higher agricultural yields and more biodiversity across a larger area.220 More recently,221 a broadening of the conceptual approach has indicated that land-sparing is also potentially better for other aspects of sustainability: per unit of production, land-efficient systems generate lower negative externalities (such as GHG emissions).

Addressing the second point on spillover effects, at a relatively small spatial scale (e.g. landscape scale) the proximity of areas of nature reserve (or otherwise spared land) and intensive agricultural areas can be problematic if the intensive agriculture impacts on biodiversity within the spared land (e.g. from pesticide drift or nutrient leakage), or if the area of spared land is too small and too fragmented to allow viable wildlife populations to exist.

The third point is that while the land-sharing versus land-sparing debate is useful because it forces consideration of the spatial issues associated with biodiversity conservation and agricultural land, it is problematic when it comes to governance. Who will determine what land is shared and what is spared?222 To date, there are no real examples of operational land-sparing strategies. Often the reverse applies: as intensification in an area increases, so do farm profits, incentivizing conversion of unmanaged land into agriculture. To avoid this, land-sparing needs to be strongly regulated, and land set aside requires some degree of statutory protection. At the moment, while protection may often exist on paper, weak enforcement means that protected areas are being exploited in many jurisdictions.223

It is key to recognize that land could in effect be spared by shifting to less resource-intensive diets. Hence, land-sparing does not always require an intensification of agricultural land elsewhere to compensate.

Another land management option is the ‘integrated landscape approach’: a basic framework for integrating multiple land uses within a given area, aimed at maintaining biodiversity, ecosystem services and feedback between the two to ultimately benefit humans. The focus of this approach to date has mostly been on maintaining heterogeneity via mosaic landscapes, habitat corridors and crop variety. Kremen and Merenlender224 describe numerous initiatives (particularly in Latin America and Africa) that have been initiated by governments (and, in certain cases, by NGOs) and involve multiple stakeholders.

It is key to recognize that land could in effect be spared by shifting to less resource-intensive diets. Hence, land-sparing does not always require an intensification of agricultural land elsewhere to compensate. For example, Hayek et al.225 demonstrate that a global shift to a plant-based or EAT-Lancet diet would substantially reduce the requirement for pasture and cropland (taking into account human nutritional needs and population growth to 2050); such land could thus be spared for nature.

5.2.3 Adapting the way we farm the land

The discussion above highlights the point that minimizing the impact of food production on biodiversity means minimizing the amount of land used for agriculture and leaving as much land as possible free for nature. However, this creates a further conundrum: if we want to preserve land for nature, we need to grow more on the land we use. Yet this is the very definition of ‘intensification’. Can it be done in a way that reduces the damage from intensive farming? This conundrum is at the heart of the concept of ‘sustainable intensification’.

If society demands more food without expanding the land area under agriculture (either because the land is valuable for other uses – for example, the biodiversity and carbon sink properties embedded in tropical forests – or because it is too marginal), then demand will only be met by growing more in the same area. This can be achieved in various ways, but the methods chosen should be sustainable and not have negative impacts on the environment or farm livelihoods. This basic conceptual definition of sustainable intensification226 has been present in the literature for many years, but the term itself was promoted in a report by the UK’s science academy, the Royal Society. The report concludes:

We must aim for sustainable intensification — the production of more food on a sustainable basis with minimal use of additional land. Here, we define intensive agriculture as being knowledge-, technology-, natural capital- and land-intensive.227

In this sense, sustainable intensification can be achieved by using more knowledge, labour, capital and/or inputs (whether synthetic or organic) – in other words, there is a range of ways to boost yields per unit area. Urban food gardens are often higher-yielding than horticultural farms because they are more intensive in terms of labour inputs. Sustainable intensification, therefore, does not necessarily imply that the entire world should adopt Westernized, large-scale, input- and capital-intensive farming systems.228

5.2.3.1 Ecological intensification

Sustainable intensification describes a conceptual goal which, at one level, is difficult to disagree with (if intensification is needed, it needs to be sustainable). Other words have been used for essentially the same concept. For example, in 1999 Ken Cassman used the term ‘ecological intensification’:

At issue, then, is whether further intensification of cereal production systems can be achieved that satisfy the anticipated increase in food demand while meeting acceptable standards of environmental quality. This goal can be described as an ecological intensification of agriculture.229

Other authors use the term ‘ecological intensification’ more specifically to mean utilizing ecosystem functions to deliver sustainability gains while maintaining yields, productivity gains or resilience.230 In essence, this means substituting synthetic inputs with enhanced ecological processes (such as soil fertility, pollination and natural pest control). Replacement of inputs may not count as intensification per se (i.e. leading to higher yields), but nonetheless it can be seen as a part of the sustainable intensification paradigm in making currently intensive systems more sustainable.231 In other examples, utilizing ecological processes has the potential to enhance yield growth, perhaps especially in existing, relatively extensive systems in the developing world. According to Tittonell, ‘Food production can increase and at the same time be sustainable through the ecological intensification of current agriculture, making intensive and smart use of the natural functionalities that ecosystems offer.’232

Conceptually, sustainable intensification can be subdivided233 into three main steps: (1) increasing efficiency, (2) substitution and (3) system redesign. Included in (1) are elements such as precision agriculture: the use of a range of technologies to better target the efficient use of inputs (the right source, in the right amount, in the right place, at the right time – the ‘4 Rs’ principle).234 This route to sustainable intensification is sometimes called ‘doing more for less’. Substitution includes replacing practices that have higher impacts with those that have lower impacts: for example, integrated pest management instead of routine pesticide usage. System redesign includes radical changes to farming practices in ways that can achieve both productivity and environmental goals.

Regenerative farming practices, organic farming, agroforestry, extensive farmed animal systems and mob-grazing all conceptually fit under steps (2) and (3) above. Within the constraints of sustainable management, what approaches can maximize the yields in a given locality?

5.2.3.2 Agro-ecology and regenerative farming

Many agro-ecological and regenerative farming systems – such as organic farming – are inherently more diverse, relying on polycultures and rotations. In general, the yield–biodiversity relationship means that such systems tend to be lower-yielding than intensive farming. Hence, large-scale adoption of such techniques would require other fundamental changes to food systems to reduce overall demand for food (including a reduction in food waste, and shifts to plant-based diets). Organic farming uses fewer synthetic fertilizers and pesticides, restricts the types of synthetic fertilizers and pesticides used, promotes crop rotations, focuses on soil fertility and closed nutrient cycles, and has diversity as an organizing principle.235 While there are many environmental benefits, organic systems produce lower yields compared to conventional production systems. Therefore, under a scenario in which all food production used organic techniques, the land requirement for agriculture would increase. However, combined with a reduction in food waste and shifts to plant-based diets (allowing a reduction in farmed animals and feed crop production), organic agriculture could contribute to feeding more than 9 billion people in 2050. Not only could this scenario result in sufficient food availability globally, it would offer positive outcomes across a range of environmental indicators, including a reduced requirement for cropland.236

Under such a scenario, it would be important to consider how to replace animal-sourced inputs used in organic production, such as manure and fertilizer derived from blood and bones. Stock-free farming techniques require no animal-sourced inputs and are likely to be an important part of the food system transformation. Numerous farms around the world rely solely on stock-free inputs. One example is Tolhurst Organic in the UK, which produces around 120 tonnes of vegetables every year on 19 acres of field. The farm’s carbon footprint is reportedly 8 tonnes per year, around the same as an average UK household.237 Tolhurst Organic claims to have increased biodiversity on its farm over the past 20 years, and a range of species is now present that includes water voles, barn owls, polecats, kingfishers and orchids.238 Green manure, or cover crops, are used to build fertility, improve soil structure, protect against erosion, suppress weeds and attract pollinators.

Agroforestry encompasses a range of methods that combine the cultivation and management of trees with food production. Polycultures of trees are used to produce wood, nuts and fruits – and allow the combination of multiple crops and cropping opportunities throughout the year.239 For example, ‘shadow systems’ combine trees with cash crops such as cocoa, with the tree cover beneficial in providing sufficient shade for food crops. Other methods utilize leguminous shrubs to improve fertility and soil structure in between cropping.240 Agroforestry relies on the interactions among multiple components, in contrast to traditional forestry and agriculture, which focus on individual components. Multifunctional landscapes of this kind also help protect against soil erosion and support the natural recharge of groundwater, thereby limiting further degradation of biodiversity and enhancing the productivity of land in the longer term.241 Levels of nutrients and organic matter in the soils are found to increase with the adoption of agroforestry in both temperate and tropical regions.242 And, in supporting ecosystem provisioning such as natural pest control and pollination,243 agroforestry can lessen the need for chemical inputs to support productivity. Studies of coffee and cacao production in tropical regions suggest that, while species richness is lost in the conversion of natural forest to agroforest, the scale of loss is lower than that associated with conversion to more intensive farming systems such as plantations.244

Agroforestry and agro-ecological practices can allow for habitat restoration while diversifying income streams and food supply, in turn increasing the resilience of local communities and habitats, improving nutrition and enhancing biodiversity.245

5.2.3.3 Good governance

As mentioned earlier, the term ‘sustainable intensification’ is contested.246 Too often it is interpreted as a licence to adopt ‘industrial’ intensive farming practices. This does not follow the concept of sustainable intensification:247 biodiversity is best served by minimizing the area of land used for agriculture; where land is used for agriculture, it should be managed in such a way as to deliver the highest possible rate of crop growth (i.e. the intensification) consistent with this also being sustainable. This requires stronger governance (e.g. regulatory frameworks, well enforced) and market incentives to ensure that intensification is truly sustainable, and that it does not simply reinforce the ‘Jevon’s paradox’248 at the heart of the ‘cheaper food’ paradigm.249 Sustainable intensification is most likely to have real impacts in regions where productivity is low as a result of management limitations: in such places, adopting best practice in agro-ecological farming would both enhance yields and benefit the environment. Such areas can mainly be found in Africa, Latin America, Eastern Europe and South Asia. Bringing yields to within 95 per cent of their local potential for 16 important food and feed crops could add 2.3 billion tonnes per year of new global production, a 58 per cent increase,250 and relieve land-use pressure elsewhere in the system. Similarly, if adaptation and technological efforts focus on the sustainable enhancement of yields in many low- and middle-income nations, there is potential to see significantly lower levels of land clearing, GHG emissions and nitrogen use globally in meeting future food needs.251 This point is also relevant because many low-GDP countries with the potential to expand their output also often contain or overlap with ‘biodiversity hotspots’ where the potential negative biodiversity impacts of irresponsible development could be large. But if sustainable enhancement of yields is to work for nature, strong regulation is needed to ensure natural ecosystems are spared and protected, and that any intensification is, indeed, sustainable.252

5.2.3.4 Community-based approaches to sustainable farming

An important element of increasing yields sustainably is promoting best practice so that capacity can be built to deliver yields in a sustainable manner. Seventy-two per cent of all farms in the world are smaller than one hectare in size, with such holdings highly dominant in Asia and Africa (mainly South Asia and sub-Saharan Africa).253 In terms of technology transfer combined with promoting biodiversity, many approaches are emerging or have already proven successful. Community-based methods such as farmer field schools, community seed banks or community forestry254 could be customized based on specific socio-economic and environmental settings.255 However, more investment is needed to enable such innovations to be scaled up. Initiatives such as participatory on-farm research, the promotion of low-impact and healthy diets, and the localization of food systems have been found to engage different actors in food systems, including consumers and grassroots movements.256 Community-based approaches are increasingly considered models for promoting multifunctional, multi-use, multi-stakeholder forestry to achieve improved forest governance and sustainability.257

5.2.3.5 Agro-biodiversity

An important element of biodiversity in agricultural landscapes is the genetic diversity of the produce farmed. This is often encompassed in the term ‘agro-biodiversity’. Most of the global genetic diversity in agriculture is associated with low-input farming systems,258 and this resource is important to low-income societies’ food sovereignty as well as to global food sustainability.

Incentivizing more diverse agriculture has many benefits. It potentially allows healthier diets through a greater diversity of fruit and vegetable production. It provides more diverse, heterogeneous landscapes. It leads to potentially more resilient farmer livelihoods and food systems.259 It also ensures the maintenance of a diverse supply of foods that may be useful in future. On a global basis, about half of the calories consumed come from wheat, rice and maize, yet as many as 300,000 plant species are potentially edible. A recent survey of what is eaten in India suggests about 1,500 species are consumed.260 Ensuring wild relatives of existing species survive is an important way to preserve potentially useful genetic diversity. This is perhaps most important in terms of adaptation to environmental and climate change (e.g. ensuring that the genetic resources of wild relatives for surviving extreme heat are available for cross-breeding programmes to maintain food supplies as the climate changes). Maintaining a diversity of crops therefore potentially maintains the ability to have a resilient food system in the future.

However, we recognize that (a) intensification of capture fisheries impacts both target fish and non-target biodiversity through perturbing habitat and ecosystems, in similar conceptual ways to farming’s impact on on-farm biodiversity; and that (b) fish ‘farming’ or aquaculture leads to significant spillover effects to local ecosystems (e.g. clearing mangrove forest for prawn fisheries; genetic contamination from farmed to wild populations; pollution from farms into the wider aquatic environment).

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Benton, Vickery and Wilson (2003), ‘Farmland biodiversity: is habitat heterogeneity the key?’; and Dainese et al. (2016), ‘Landscape simplification weakens the association between terrestrial producer and consumer diversity in Europe’.

Ibid.

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Food system impacts on biodiversity loss

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05 Technical annex

5.1 The impacts of today’s food system on biodiversity

Figure 6. Trends in world agriculture

Figure 6. Trends in world agriculture

5.1.1 Impacts at farm scale

5.1.1.1 Homogenization of farmland

5.1.1.2 Disruption of ecological communities above and below ground

5.1.1.3 Pollution of aquatic ecosystems

5.1.1.4 Loss of large herbivores through grazing of farmed animals

Box 6. Pastoralist/grazer/wildlife conflict in Botswana

5.1.2 Impacts at landscape scale

5.1.2.1 Reduced landscape heterogeneity

5.1.2.2 Disruption of ecosystem services

5.1.2.3 Nutrient pollution at catchment level

5.1.3 Impacts at regional and global scale

5.1.3.1 Pollution of rivers and regional-scale impacts

5.1.3.2 Air pollution

5.1.3.3 Changes to population processes

5.1.3.4 Land-use change and teleconnections: market connectivity across space

5.1.3.5 Climate change’s global impacts

5.1.3.6 Interactions with aquatic food production systems

5.2 Options for implementing food system redesign in support of biodiversity

5.2.1 Demand-side changes to relieve pressure on land

Figure 7. Estimated global variation in GHG emissions, land use, terrestrial acidification, eutrophication and scarcity-weighted freshwater withdrawals, within and between 36 major foods

Figure 7. Estimated global variation in GHG emissions, land use, terrestrial acidification, eutrophication and scarcity-weighted freshwater withdrawals, within and between 36 major foods

5.2.2 Setting aside land for biodiversity

5.2.3 Adapting the way we farm the land

5.2.3.1 Ecological intensification

5.2.3.2 Agro-ecology and regenerative farming

5.2.3.3 Good governance

5.2.3.4 Community-based approaches to sustainable farming

5.2.3.5 Agro-biodiversity