Overview

The article I reviewed is Enhancing pollination supply in an urban ecosystem through landscape modifications by Davis et al. (2017), published in Landscape and Urban Planning. As urban farming becomes more common, understanding how to support pollinators in cities is increasingly important. This study examines whether converting small portions of turf grass into flowering habitat could increase pollinator supply and benefit urban agriculture. The researchers used Chicago, Illinois, as their study area and focused on modeling how different strategies for increasing floral resources, such as planting flowers in city parks, residential yards, or near community gardens, would impact pollination availability. The goal was to help city planners and residents find the most effective way to support pollinators and improve crop yields in urban gardens.

Methods

The researchers first mapped the locations of urban farms, community gardens, and home food gardens using Google Earth imagery. They then collected pollinator specimens from 15 community gardens across Chicago using colored pan traps filled with a detergent solution. Traps were arranged in a 3 x 3 meter grid, spaced one meter apart, with alternating colors, and left out for one daylight cycle each month during July, August, and September 2009.

Specimens were preserved in ethanol and later identified to genus or species. Using this field data, the team validated the InVEST pollination model, which uses land cover, nesting resources, and floral resources to predict pollinator abundance. They then modeled several scenarios simulating the conversion of one to five percent of Chicago’s turf grass to pollinator-friendly flower gardens in different locations, including city parks, private yards, and areas within varying distances of community gardens, to compare how each strategy affected pollination supply across the city.

Results

The study found that augmenting floral resources can increase pollination supply in Chicago, but the most effective strategy depends on the type of urban agriculture. For home gardens, distributing flowers throughout the city was most beneficial, while concentrating flowers near community gardens and urban farms provided the greatest pollination benefits for those larger sites. The InVEST model predicted 46 percent of the variation in native bee richness, indicating that it can reliably identify areas with high or low pollination potential. The results highlight that city parks, forest preserves, and green spaces act as pollination hotspots, whereas downtown and heavily industrialized areas may have lower pollination supply.

Fig. 1. Study area (Chicago, Illinois)with inset of United States.

Fig. 2. Map of pollination supply score and location of sites used for model validation, i.e. sites where bees were collected.

Fig. 4. Effect of landscape modification scenarios on pollination supply scores.

Critiques and Reflection

While this article provides valuable insight into the role of bees in urban pollination and demonstrates how modifying turf grass can enhance pollinator supply for both residential and commercial agriculture, it has some limitations. One notable omission is the lack of consideration for other important insect orders, such as Diptera (flies) and Lepidoptera (butterflies and moths), which also play critical roles in pollination. Including these groups could provide a more complete understanding of urban pollinator communities.

The study excels in highlighting the underutilized potential of urban green spaces, particularly turf grass and ornamental plantings, and shows how thoughtful landscape modifications can provide both ecological and economic benefits. However, greater attention could be given to the use of native plantings, which not only offer nectar resources but also serve as host plants for pollinators, contributing to the restoration of urban biodiversity and supporting the life cycles of native insects.

Despite these limitations, the article provides strong empirical evidence for the importance of maximizing the ecological value of urban green spaces. It demonstrates that targeted interventions, such as converting portions of turf grass to flower gardens, can meaningfully enhance pollinator populations and improve urban agricultural productivity, making it a valuable resource for both researchers and urban planners.

Reference 

Amélie Y. Davis, Eric V. Lonsdorf, Cliff R. Shierk, Kevin C. Matteson, John R. Taylor, Sarah T. Lovell, Emily S. Minor. (2017). Enhancing pollination supply in an urban ecosystem through landscape modifications, 162, 157-166. https://doi.org/10.1016/j.landurbplan.2017.02.011