2_Exhibits A, C & D - Laserfiche WebLink

HORTICULTURE I ARBORICULTURE I URBAN FORESTRY Guide to Care of California Native Oaks HORT SCIENCE Landscaping Around Oaks Native oaks are adapted to conditions of cool, wet winters and warm, dry summers. They are accustomed to a period of prolonged drought in the summer months. This pattern does not change even though development is placed around them. Oaks are intolerant of heavy irrigation during the summer. Installation of new landscapes around oaks must recognize and respect this fact, Lawn, flowers, ivy, azaleas, ferns or other plantings requiring frequent watering are inappropriate around oaks. Evan so, attractive landscapes can be created around the trees. The best treatment under oaks is to place a thick layer of organic mulch such as bark or wood chips. Alternatives are rock or cobble mulches that can simulate dry streambeds. Maintain existing surface drainage away from the base of the trunks so that water does not flow to the base of the trees. Species appropriate beneath oaks are: less than 4'tall when mature, shade tolerant and will require irrigation no more than once a month. Do not plant within 10' of the trunk. Because oaks do not tolerate heavy irrigation, the design and maintenance of the irrigation system must accommodate the tree. There should be no irrigation within ten feet of the trunk. In general drip, micro-sprinklers or bubblers that wet a small area around each plant work better than spray nozzles. The layout of the system must be designed to avoid damaging roots during installation. The best way to minimize damage to the oaks is to avoid laying irrigation lines within the dripline. If you chose to plant in that area and want to install an irrigation system, consider laying the pipe on the surface rather than in trenches that cut through the roots. The pipes can be covered with deep mulch. If you must place pipe underground within the dripline of the tree, dig the trenches by hand so that woody roots can be left intact. Dig a tunnel under the roots and thread the pipe underneath. In this way, the roots that transport water and minerals to your tree will continue to function. In summary, the following are general guidelines for landscaping around oaks: 1. The best treatment under oaks is a thick layer of organic mulch, such as bark, wood chips or leaf litter. Prunings may be chipped by an arborist and left beneath the canopy. Alternatives include use of rocks or cobbles. In all cases, drainage must be away from the trunk. 2. Use wood decking on piers rather than patios under the driplines of trees. Allow at least 1' clearance between the deck and tree trunk. 3. Select plants that are shade and drought tolerant (no more than one irrigation per month). No plants should be installed within 10' of the trunk of the tree. A list of species appropriate for use under oaks is listed in Table 1. 4. Irrigation systems must be very carefully designed to avoid trenching through roots. No irrigation lines shall be placed under the driplines of HortScience,Inc E 325 Ray St. I Pleasanton, CA 94566 phone 925.484.0211 I fax 925.484.50961 www.hortscience.Com ll not be placed within the TREE PROTECTION ZONE, either temporarily or permanently. Any modifications must be approved and monitored by the Consulting Arborist. 2. All demolition, excavation and construction within the dripline of trees shall be done using the smallest equipment possible. The Consulting Arborist will identify where hand excavation may be required. Motorized equipment shall not be used within the TREE PROTECTION ZONE. 3. Prior to excavation for the demolition and construction the tree may require root pruning outside the TREE PROTECTION ZONE by cutting all roots cleanly to the depth of construction. Roots will be exposed by either: pulling soil away from the tree by digging , normally 54"above grade. A multi-branched tree, which has