Developed site area open space tree plantings also called minimum canopy standards area base upon a percentage of all viable trees removed on the site. These trees shall be planted on the site in available open spaces, zoned planting areas such as street yards, buffers, vehicular use areas shall be planted within pervious areas of each lot or tract. The purpose of these plantings is to replace existing trees removed and to provide canopy coverage and shade around parking lots and exposed building walls. Open space to receive these trees shall be calculated to maintain a proscribed site open space ratio (OSR) or permeability ration (PR) as required by the Design Manual. Developed site open space may also contain micro-detentions, infiltration trenches, underground storm water storage chambers, sand filters, and other water conservation or on-site storm water management facilities as illustrated in the proto-typical.
Community are beginning to realize that the urban tree canopy provides many eco-services that make city living more pleasurable. To this end, community landscape codes and tree preservation ordinances are written to identify the tree canopy on each development site. Trees are inventoried and they are analyzed in regard to composition, size, species and health of existing trees that grow there. Total caliper inch by species is often recorded and in some communities total canopy area is calculated to understand shading and cooling effects. These communities may set limits on which trees can be removed and how they are to be replaced. Most are replaced on site, some planted in tree banks on public lands and others mitigated by cash in-lieu-of made payable to a community tree foundation. Money placed in the foundation is used to plant trees to restock the community tree canopy.
When replaced on site, these trees may be planted in any available open space or even within one of the designated landscape zones used for beautification, screening, buffering, shading, or urban wildlife habitat protection. However, TDU trees do not replace and are not substitutes for any plants that may be required by other sections of the landscape code.
