Urban Canopy

From Palo Alto Wiki

The urban canopy in Palo Alto is tended to by city arborists. Arborists are staffed in two strategic areas of responsibility. According to the Palo Alto city Web site, the Public Works Arborist "insures a professionally administered street tree replacement program is ongoing...The Planning Department Arborist provides professional guidance for the public, reviews landscape architecture and development plans, code and condition monitoring and interacts with city staff and special interest groups."

Palo Alto has been granted the rating of Tree City USA for the past 22 years from the National Arbor Day Foundation.

Contents 1 Urban Forestry Program 2 Diversity 3 Heritage Trees 3.1 The Seven Heritage Trees

[edit] Urban Forestry Program

Part 1: Tree Management. The Public Works Arborist and Planning Department Arborist work together to protect and manage trees proactively.

Part 2: City of Palo Alto/Canopy: Trees for Palo Alto and Community Residents coalition. The cooperation between city staff, residents and the non-profit organization Canopy has resulted in successful protection of Palo Alto trees.

Part 3: Tree Preservation and Management Regulations. These are the city's primary regulatory tool to provide for orderly protection of specified trees on private and public property. The Tree Technical Manual is authorized to establish specific technical regulations, standards and specifications necessary to implement the Ordinance and provide guidance for the required or recommended care, removal and replacement of regulated trees.

[edit] Diversity

The only trees native to Palo Alto are redwoods and oaks. However, city arborists and urban foresters recommend other species as ideal street trees. Thus, using purely native trees is not realistic - especially when the city is looking to landscape and grow a large urban forest.

Valley and coast live oaks in their natural environment can withstand periods with very little water. During dry summers, fungi and molds native to Palo Alto soil are dormant. Adding water wakes up the fungus, which immediately eats oak root. Thus, problems result when the city wants to water the lawn around an oak tree.

Likewise, the magnolias that line University Avenue are difficult to tend due to their aggressive, thirsty root systems.

Having a diversity of trees minimizes the chances of having a tree disease spread and make the urban ofrest more likely to stay around through shifts in weather. More types of trees allows less potentially devastating problems. The city plants 200 to 300 trees a year, including the current street trees of choice, London planes, northern red oaks, silver lindens and American ashes.

[edit] Heritage Trees

A heritage tree is designated as such by the City Council. A tree can be nominated by any person with the consent of the property owner(s). A nominee must be found to be unique and of importance to the community due to any of the following factors:

It is an outstanding speciment of a desirable species
It is one of the largest or oldest trees in Palo Alto
It possesses distinctive form, size, age, location, and/or historical significance.

[edit] The Seven Heritage Trees

1. The El Palo Alto Redwood is located in El palo Alto Park on the banks of San Francisquito Creek. It is California Historical Landmark #2. The Sequoia sempervirens, Coast Redwood is 90 inches in diameter, 110 feet tall, and has a crown spread of 40 feet. As of 2002, it is 1061 years old. Apparently, it is healthier today than 100 years ago.
2. The Rinconada Oak is located in Rinconada Park along Embarcardero Rd. The Quercus agrifolia, Coast Live Oak is 52 inches in diameter, 75 feet tall and has a crown spread of nearly 120 feet. The tree is over 200 old and was dedicated by Mayor Liz Kniss in 1994.
3. Coast Redwood, is on private property (rear of 3759 La Donna Street). The Sequoia sempervirens, Coast Redwood is 64.6 inches in diameter, 125 feet tall and has a crown spread of nearly 25 feet. In 1999, was estimated to be over 100 years old.
4. Dawn Redwood, is on private property (front of 1032 Forest Avenue). The Metasequoia glyptostrobodies, Dawn Redwood is 27 inches in diameter, 48 feet tall and has a crown spread of nearly 40 feet. In 1999, the tree was estimated to be nearly 50 years old.
5. Silver Maple, is on private property (rear of 1872 Edgewood Drive). The Acer saccarinum, Silver Maple is 55.2 inches in diameter, 72 feet tall and has a crown spread of nearly 95 feet. In 2000, the tree was estimated to be over 50 years old.
6. American Elm, is on private property in the center of the San Alma Homeowners Association property, 4256 Ponce Drive, on the site where Don Secundo Robles (owner of all the land that is now Palo Alto) built his adobe home sometime before 1840. The Ulmus americana, American Elm is 39.5 inches in diameter, 60 feet tall and has a crown spread of nearly 60 feet. In 2000, the tree was estimated to be over 50 years old.
7. Aleppo Pine, is on private property (front of 12291 Ramona Street). The Pinus halepensis, Aleppo Pine is a twin-trunk combined 73 inches in diameter, 55 feet tall and has a crown spread of nearly 60 feet. In 2004, the tree was estimated to be nearly 70 years old. Designated by City Council Resolution, the tree has been described as 'the best example of an Aleppo Pine in all of Palo Alto', by Jim McClenahan, a member of the American Society of Consulting Arborists.