Monday, March 18, 2013

Working With Existing Trees IV


I am the Landscape Architect for the California Health Sciences University (CHSU) in Central California. The CHSU site is characterized by rolling hills, a board grassy plain and features a number of individual trees and informal groves of native Blue Oak trees(Quercus douglasii). The oaks are all that have survived the agricultural history of cattle grazing that removed the native grasses and shrub communities.  All the other trees, including the Gray Pine (Pinus sabiniana), were removed by fire or for building construction.

The existing oaks are the basis for the CHSU Campus Landscape Strategy, and are being saved and featured as markers of the site’s landscape heritage. Saving the oak trees also assists in the reestablishment of the native Central California oak woodlands, and informs the campus landscape and architectural development: the oak woodlands are well-adapted to the hot and dry climate, support conservation of water resources and reduce the use of chemical fertilizers and pesticides that are typically required for conventional landscapes.

Preserving the native oak trees requires a comprehensive approach. Native oak trees are very sensitive to grade changes and ground compaction from the trees’ trunks to the drip line at the outer edge of the trees’ canopies.  Native oaks grow in groups responding to the presence of water in natural drainage ways or groundwater aquifers and seeps, hence these water features need to be preserved and maintained.

In addition, we recommended fencing the oaks in groves following the collective canopy drip lines to prevent vehicular or other development-related intrusions into the groves. The fencing serves as a constant reminder to stay away from the oaks during the development stages of the CHSU site, and facilitates native landscape regeneration. Range land fencing of pressure treated wood post and wire is the most visually unobtrusive fencing of the oak tree groves and relates to the local rural agricultural character as shown in the adjacent image.