Trees in Our Town


  • Trees muffle urban noise.
  • Mature, leafy trees can release as much oxygen as 10 people inhale in a year.
  • Trees lock up carbon dioxide and reduce global warming.
  • Evaporation of water from tree leaves can cool the surrounding air.
  • Trees act as windbreaks.
  • Trees reduce runoff and erosion.
  • Trees increase property values.


  • The Old Sycamores of San Lorenzo

    A hybrid developed from the American sycamore, called the London planetree, is the urban tree of choice in North America and Europe. When David Bohannon built San Lorenzo Village between 1943 and 1950, he chose the venerable sycamore as a street tree. Many parts of the village are still graced by these historic trees. Regrettably, many residents have removed these trees without replacing them, leaving some streets barren.

    The sycamore is a member of one of the planet's oldest clan of trees (Platanaceae) and paleobotanists have dated the family to be over 100 million years old. Living sycamore trees can reach ages of 500 to 600 years. The record American sycamore, according to The Urban Tree Book and the Big Tree Register, is 129 feet tall. This Jeromesville, Ohio tree has a limb spread that spans 105 feet and the trunk measures 49 feet in circumference.

    After 200 or 300 years the sycamore trunk becomes hollow. Colonial record-makers crammed into sycamore trunks like modern fraternity brothers packing into telephone booths or small cars. In Ohio there were specimens that could hold 15 men on horseback or 40 men on foot!

    One of the oldest sycamores still standing predates the Revolutionary War. It was on hand to witness the bedraggled troops of George Washington parade into Newark in freezing rain on their painful path of retreat across New Jersey. For the story, see Survivor of the Revolution.

    When Frederick Law Olmstead designed New York City's Central Park, he had many sycamore trees planted where some continue to flourish. Well over half of London's street trees are planetrees. Many American and western European cities have planted planetrees, including Philadelphia which has counted over half a million.

    Sycamore seeds accompanied the lunar orbit of Apollo 14 in 1971 and were planted across from Philadelphia's Independence Hall.

    Sycamore wood is used for furniture, millwork, flooring, butcher blocks, and musical instruments. With little resistance to decay, the wood is hard, tough and almost impossible to split. The pioneers cut trunks of great dimension into cross-sections and then bored through the center to make primitive wheels for ox carts. Sycamore wood was also used to make wooden barber poles, wooden washing machines, and wooden stereoscopes.

    The underside of the sycamore leaf is so soft and fuzzy it was used by the native Americans for toilet paper!

    For more information, see American sycamore.


    Alameda County Ordinance Regulating Street Trees

    The Alameda County Board of Supervisors adopted an ordinance (2002-77) effective May 1, 2002 establishing standards and regulations for planting, maintaining, removing trees within the county's right-of-way in local streets. See Regulation of Trees in County Right of Way (General Ordinances, title 12, Chapter 12.08, sections 540 - 580).

    The ordinance applies in the unincorporated areas of the county. In San Lorenzo Village the county has a right-of-way extending from the center of each street to a point beyond the sidewalk, usually four or five feet.

    Planting, trimming, pruning, and removing trees within the right-of-way must be done according to standards set by the Director of Public Works. A property owner who wishes to plant a street tree -- that is, a tree within the county's right-of-way -- or transplant, prune, or remove such a tree, must first get a permit from the Public Works Agency.

    Planting. Tree planting in the county's right of way must be done by a licensed contractor.

    Trimming. Tree trimming of street trees must be done by a licensed contractor or the county Public Works Agency, and it must comply with the standards of the International Society of Arboriculture.

    Removal. After removal, a street tree must be replaced within 90 days at the property owner's expense. See the list of replacement trees recommended by the county arborist.

    The ordinance is administered and enforced by the county's Public Works Agency. A Tree Advisory Board, composed of five citizens from throughout the county, meets quarterly to advise the director of public works and to hear protests from property owners. See Alameda County Urban Forest Program.

    For further information on the ordinance, the Tree Advisory Board, or to report removal of a street tree, call the "tree permit hotline," 670-6467.


    Information on Trees

    Tree trimming in San Lorenzo -- PGE trims top branches to clear power lines, while Alameda County Public Works Agency trims lower branches to clear streets and sidewalks.

    Excite's directory of tree varieties -- links to websites that have information on each species.

    Friends of the Urban Forest -- offers financial, technical, and practical assistance to individuals and heighborhood groups that want to plant and care for trees.

    International Society of Arborists -- find a certified tree arborist in this area.


    [Revised June 11, 2012]