Global food production faces great challenges in the future. With a future world population of 9.6 billion by 2050, rising urbanization, decreasing arable land, and weather extremes due to climate change, global agriculture is under pressure. While today over 50 % of the world population live in cities, by 2030, the number will rise to 70 %. In addition, global emissions have to be kept in mind. Currently, agriculture accounts for around 20–30 % of global greenhouse gas emissions. Shifting food production to locations with high demands reduces emissions and mitigates climate change. Urban horticulture increases global food production by exploiting new locations for cultivation. However, higher land prices and urban pollution constrain urban horticulture. In this paper, we review different urban cultivation systems throughout the world. Our main findings from ecological, economical, and social aspects are: (1) Urban horticulture activities are increasing globally with at least 100 million people involved worldwide. With potential yields of up to 50 kg per m2 per year and more, vegetable production is the most significant component of urban food production which contributes to global food security. (2) Organoponic and other low-input systems will continue to play an important role for a sustainable and secure food production in the future. (3) Despite the resource efficiency of indoor farming systems, they are still very expensive. (4) Integrating urban horticulture into educational and social programs improves nutrition and food security. Overlaying these, new technologies in horticultural research need to be adopted for urban horticulture to increase future efficiency and productivity. To enhance sustainability, urban horticulture has to be integrated into the urban planning process and supported through policies. However, future food production should not be “local at any price,” but rather committed to increase sustainability.

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Urban vegetable for food security in cities. A review

Urban areas are often perceived to have lower biodiversity than the wider countryside, but a few small-scale studies suggest that some urban land uses can support substantial pollinator populations. We present a large-scale, well-replicated study of floral resources and pollinators in 360 sites incorporating all major land uses in four British cities. Using a systems approach, we developed Bayesian network models integrating pollinator dispersal and resource switching to estimate city-scale effects of management interventions on plant–pollinator community robustness to species loss. We show that residential gardens and allotments (community gardens) are pollinator ‘hotspots’: gardens due to their extensive area, and allotments due to their high pollinator diversity and leverage on city-scale plant–pollinator community robustness. Household income was positively associated with pollinator abundance in gardens, highlighting the influence of socioeconomic factors. Our results underpin urban planning recommendations to enhance pollinator conservation, using increasing city-scale community robustness as our measure of success.

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A systems approach reveals urban pollinator hotspots and conservation opportunities

Beyond agricultural innovation systems? Exploring an agricultural innovation ecosystems approach for niche design and development in sustainability transitions

The present work, focusing on the theme of food production and consumption in urban areas, analyses the relationships among three factors: city, human well-being and ecosystems. A case study was carried out addressing the quantification of the potential of rooftop vegetable production in the city of Bologna (Italy) as related to its citizens’ needs. Besides the contribution to food security of the city, the potential benefits to urban biodiversity and ecosystem service provision were estimated. The methodology consisted of: 1) experimental trials of potential productivity of simplified soilless systems in rooftop gardens (RTGs); 2) detection of all flat roofs and roof-terraces and quantification of the potential surfaces that could be converted into RTGs; 3) identification of the city’s vegetable requirements, based on population and diet data; 4) calculation of the proportion of vegetable requirement that could be satisfied by local RTG production; 5) identification of other benefits (improvement of urban biodiversity through the creation of green corridors and estimation of carbon sequestration) associated with the increased area of urban green infrastructure (GI). According to the present study, RTGs could provide more than 12,000 t year−1 vegetables to Bologna, satisfying 77 % of the inhabitants’ requirements. The study also advances hypotheses for the implementation of biodiversity roofs enabling the connection of biodiversity rich areas across and close to the city: these would form a network of green corridors of over 94 km length with a density of about 0.67 km km−2.

Exploring the production capacity of rooftop gardens (RTGs) in urban agriculture: the potential impact on food and nutrition security, biodiversity and other ecosystem services in the city of Bologna

The role of urban agriculture in global food security is a topic of increasing discussion. Existing research on urban and peri-urban agriculture consists largely of case studies that frequently use disparate definitions of urban and peri-urban agriculture depending on the local context and study objectives. This lack of consistency makes quantification of the extent of this practice at the global scale difficult. This study instead integrates global data on croplands and urban extents using spatial overlay analysis to estimate the global area of urban and peri-urban irrigated and rainfed croplands. The global area of urban irrigated croplands was estimated at about 24 Mha (11.0 percent of all irrigated croplands) with a cropping intensity of 1.48. The global area of urban rainfed croplands found was approximately 44 Mha (4.7 percent of all rainfed croplands) with a cropping intensity of 1.03. These values were derived from the MIRCA2000 Maximum Monthly Cropped Area Grids for irrigated and rainfed crops and therefore their sum does not necessarily represent the total urban cropland area when the maximum extent of irrigated and rainfed croplands occurs in different months. Further analysis of croplands within 20 km of urban extents show that 60 and 35 percent of, respectively, all irrigated and rainfed croplands fall within this distance range. S Online supplementary data available from stacks.iop.org/ERL/9/114002/mmedia

https://iopscience.iop.org/article/10.1088/1748-9326/9/11/114002/pdf

Global assessment of urban and peri-urban agriculture: irrigated and rainfed croplands

The year 2007 marked a critical event in the world history. For the first time, more than half of the world population now lives in cities. In many developing countries, the urbanization process goes along with increasing urban poverty and polluted environment, growing food insecurity and malnutrition, especially for children, pregnant and lactating women; and increasing unemployment. Urban agriculture represents an opportunity for improving food supply, health conditions, local economy, social integration, and environmental sustainability altogether. Urban agriculture is present throughout the world in a diversity of farming systems. Urban dwellers ranging 25–30 % are involved worldwide in the agro-food sector. Urban agriculture will gain in recognition for its benefits and services because urban population and rural–urban migration are increasing. The actual scarcity of knowledge on urban agriculture has somehow hindered the relevance of this activity. Here, we review the social, cultural, technical, economic, environmental, and political factors affecting urban agriculture with examples taken in East Asia, South America, or East Africa. We discuss the definition, benefits, and limitations of urban agriculture. Food security benefit of urban agriculture is evidenced by 100–200 million urban farmers worldwide providing the city markets with fresh horticultural goods. Urban agriculture favors social improvement since the poors spend up to 85 % of their income in food purchase and most urban farmers belong to poorest populations. Sociologically urban farming favors both social inclusion and reduction of gender inequalities, as 65 % of urban farmers are women. Urban agriculture has ecological benefits by reducing the city waste, improving urban biodiversity and air quality, and overall reducing the environmental impact related to both food transport and storage. The production of horticultural goods shows the main benefits of urban agriculture. Fruit and vegetable crops give high yields, up to 50 kg m−2 year−1, a more efficient use of agricultural inputs, high added value, and rapidly perishable products that can easily substitute the rural production in the local market. Urban horticulture is the most competitive branch of urban farming due to the high cost of urban land and with the need of high water- and fertilizer-use efficiency. Traditional urban horticulture systems are classified in four types: allotment and family gardens, simplified extensive systems, shifting cultivation, and intensive systems. We describe also innovative systems including organoponics and simplified soilless cultures.

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Urban agriculture in the developing world: a review

Use of HORTIVAR for retrieving information: potentialities for the urban gardener.

There is a significant increase in interest in neglected and underutilized crop species (NUS) globally, due to their high potential value nutritionally and for food security. In order to promote an enabling environment for the conservation and sustainable use of NUS, it is necessary to develop appropriate policies and legal frameworks. Essential components of these include the participation of small-scale farmers, nutritional and other food requirements of local people, and the promotion of public-private partnerships for developing new varieties and new breeding schemes of specific crops. The importance of these crops has been formally recognized in numerous policy frameworks, including in FAO's Global Plan of Action Plant Genetic Resources for Food and Agriculture and the Second Global Plan of Action for Plant Genetic Resources for Food and Agriculture. The approach must be holistic to take into account efficient seed systems and value chain development, in order to promote the continuum between conservation and sustainable use, for improved livelihoods. (Resume d'auteur)

Remi Nono-Womdim

Papers

Urban agriculture in the developing world: a review

Use of HORTIVAR for retrieving information: potentialities for the urban gardener.

Promoting neglected and underutilized species through policies and legal frameworks

HORTIVAR database as a shared framework for grapevine watching worldwide.