Webinar: The Leading Edge in Trees, Stormwater and Urban Design

This presentation will discuss the academic data behind soil volumes and soil quality standards, as well as implementation strategies and the repercussions of long-term maintenance. Urban designers don’t have the space to achieve preferred soil volumes, and trees are often shoe- horned into “Amenity Zones” in the shared public right of way. In these tight conditions, there are three options: Custom support systems, Structural soils and Suspended (supported) pavements.

Urban designers today face a number of soil challenges regarding street trees, including the lack of available soil in high-density areas. One of the strategies employed is the Street Tree Soil Volume Mandate, where a developer is required to provide a certain amount of planting soil per tree.

There are many guidelines which stipulate volumes, but there is no regard for soil quality within the regulations. Also, volume mandates lag behind the science which stipulates the volumes. The required soil can be used for several complementary goals, be it large tree growth, stormwater bioretention, heat Island reduction or urban greening. Regardless of the reason it is used, the resulting inner-city flora will have the added benefit of increasing real-estate value, a goal of most developers.

Why is not soil quality mandated as well? The research is clear, High quality, loamy soils outperform structural soils. Not only should volumes be required, but soil quality should be codified as well. Those municipalities that are rethinking the vital role trees play in the health of our planet and creating rules and recommendations to support them. They promote policies and projects that set trees up for long-term success and environmentally meaningful contribution, including soil quality as well as soil volume.

This webcast is hosted by the APA Urban Design and Preservation Division

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