Thus, the palette of plants should be different from that used on a more typical residential site. Design Around Trees Every effort should be made to design outdoor spaces and functions around existing trees. The rest of the site should be allowed to remain in its naturalized state with native ground covers and understory trees. A number of design guidelines should be considered to accomplish this. Wooded sites require special design consideration in order to preserve and enhance existing trees. These uses should, as much as possible, be molded to the existing ground while also maintaining proper standards of construction. If the site is a newly built house, it is likely that the ground will have been altered most around the house. The loss of understory plants is apt to reduce the overall health of a wooded ecology while also eliminating the ability of the wooded area to regenerate itself. paved walks, structured outdoor spaces, walls, or even lawn areas if they are part of the design. A wooded environment is simply not conducive to lawn. Existing trees may need to be allowed to extend up through these surfaces and will probably result in spaces that are more divided and complex than if the trees were not present (Figure 13—14). Compacted soil is also more difficult for roots to grow through. Plants must be chosen to fit each of these conditions. This approach is also likely to require field adjustment during construction. This concept also minimizes regrading and allows precipitation to still reach the ground. Although occasional walking through a wooded area will probably do little harm, repeated movement over the same ground will compact and damage the underlying soil. Maintain Existing Grade There should be minimal grading or alteration of the existing ground elevation on a wooded site in order to minimize disturbance of tree roots. Native wooded plants not only tolerate the special wooded conditions, but also look as if they belong to the wooded environment. A lawn frequently struggles under these circumstances, even if it is a variety that will tolerate some shade. Again, this is most significant in locating
Figure 13-13
Lawn should be eliminated or minimized in area on a wooded residential site. It might be located adjacent to the street where sun probably shines through because of the open street corridor, or the lawn might form a space near the house where it can provide some separation between the house and preserved woods (Figure 13—13). At a minimum, the existing grade should be preserved within the entire drip line of a tree or grove of trees. If significant regrading is necessary, then retaining walls or tree wells should be used to maintain the existing grade around the base of existing trees. There are several reasons for this recommendation. In addition, the installation of lawn generally requires that understory plants be removed and that the ground surface be regraded. Use Shade-Tolerant Plants Plant materials introduced to a wooded site should be carefully selected for shade tolerance. Soil compaction results from the constant use or movement, including foot traffic, across the ground. Beyond this construction zone, every effort should be made to retain the existing ground level. Then, spaces must be carefully woven among tree trunks so that few, if any, trees are removed to accommodate exterior functions. Figure 13-12
A clump of tree trunks can provide a feeling of visual separation from nearby properties.
