Urban food crop production capacity and competition with the urban forest

• We developed a geospatial method to estimate a city's maximum food crop production capacity.
• We applied the method to Seattle, WA, and found that that between 1% and 4% of Seattle's population could be supported with a complete vegetarian diet from food grown within the city.
• We modeled the effect of urban tree canopy on reducing the maximum food crop production capacity of Seattle through shading.
• We estimated the foodshed needed to support 100% of Seattle's food needs.

The sourcing of food plays a significant role in assessing the sustainability of a city, but it is unclear how much food a city can produce within its city limits. In this study, we propose a method for estimating the maximum food crop production capacity of a city and demonstrate the method in Seattle, WA USA by taking into account land use, the light environment, and a mix of food crops necessary to supply a year-round vegetarian diet. By artificially removing trees from the city, we estimate the effect of tree shading on food crop production capacity. We find that at maximum food production, urban food crops can produce between 1% and 4% of the city's food needs under the most realistic land use scenarios, and that tree shading reduces food crop production capacity between 19% and 35%. We expand beyond the city Seattle limits to find that a buffer of 58 km around the city is required to meet 100% of the city's food needs.