Equitable tree value models

Cities are more aware than ever of the benefits provided by trees, thanks to standardized toolkits for modeling tree value such as the USDA Forest Service's i-Tree Eco application. These tools use the physical characteristics of trees to compute direct benefits provided by trees through: air pollution removal, carbon sequestration, rainwater retention and reduced runoff, building energy effects such as reduced cooling loads due to shade, improved bird habitats, and reduced UV exposure. A single tree can have a net ecosystem service value of thousands of dollars. Mature street trees are associated with higher infant birth weight in poor communities, and consumers spend more on streets lined with large trees.

However, current methods for calculating trees' value do not consider context. That's why a new generation of models pioneered in cities like Pittsburgh, incorporate localized indicators of environmental distress such as heat vulnerability indices, and public health and demographics characteristics to assess the true impact of increased tree canopy size and health. Recently, a national atlas of cities' "tree equity score" was published by Chicago-based NGO American Forest Tree Equity Score tool.

The urban tree canopy today, and the benefits it produces, are products of past segregation. These signals, however, point towards a growing recognition not only of the value of trees, but the where and how expanding the tree canopy can have the greatest impact on public well-being.