Accounting for green infrastructure as assets; Oregon

Appreciating Oregon's trees OregonLive.com:
Oregon's trees may soon be fully appreciated.
In addition to cleaning our air and water and absorbing carbon, numerous studies have calculated the value of trees to our cities. One assigned a $5 billion value to Portland's trees. Another calculated the growth in tax revenues through increased home values at an average of $7,000 per tree, with a cumulative increase of $13,000 for neighboring homes.
Plus, while the value of public assets such as roads and bridges depreciate after installation, a tree's value appreciates during its first 20 years as growing roots and branches trap more pollutants and runoff every year.
Yet despite the numerous public benefits, urban tree planting and preservation aren't funded in the ways that we fund our bridges and roads.
This may be about to change. For the first time, the Oregon Department of Transportation is putting trees 'on the books' as part of the three-year project involving ODOT Region 1, Friends of Trees and Metro to green the I-205 bike and pedestrian path known as the Multi-Use Path.