Above When a street tree is starved for water, it becomes the loneliest tree in town. Ignored, neglected, constantly dodging fast moving cars and seemingly unwanted. City street trees need the help of a town arborist to survive in the city.

In most cities that do not employ an arborist or have an urban forestry program the street tree feels alone in the city. Once set out, they are left to succeed on their own: often no fertilizer, no shaping, no pruning, little mulch, limited water and poor construction grade soils. Yes, people drive by, but they often don't even notice the tree. After all, street trees are for shading public sidewalks, not necessarily for the benefit of drivers.

Many street trees are planted as specimens, as if it is for decoration rather than urban shade. If they do have a friend nearby, it would be planted some 40 or 60 feet away in a perfect formal line. The street tree is rarely planted in a grove among its family or friends. Often street trees are of the same variety with little attention paid to their design message.

When planted it is often situated in a space much too small where its roots become static, and the tree fails to grow to its natural mature size. In many situations the surface is compacted by foot traffic or the planting space is built convex so natural rainwater flows over the curb and into the street and is not allowed to enter the root zone.

When a street tree is starved for water, it becomes the loneliest tree in town. Ignored, neglected, constantly dodging fast moving cars and seemingly unwanted. City street trees need the help of a town arborist to survive in the city.

California Landscape Irrigation
Governor Brown and his Executive Order B-29-15 dropped a bomb on the landscape industry of the state calling for a statewide average water use reduction of 25%. Much of that water saving will come from minimizing water use in the landscape. Most water saving will come from removing lawn grass.

When planted it is often situated in a space much too small where its roots become static, and the tree fails to grow to its natural mature size. Photo: Editor Steve Kelly

The executive order was released to further limit the amount of irrigated landscape areas. It calls for the replacement of 50,000,000 square feet of lawn grass with "drought tolerant landscaping." Within the order were reductions to large landscape users such as campuses, golf courses, cemeteries, light industrial parks and office complexes.

The executive order restricts the use of potable water on public streets. Alameda County for instance, immediately discontinued the use of potable water for roadway medians. Their interpretation will surely reduce the amount of water available for street trees.

The most obviously seen statewide change to designed landscapes will result in shutting off water to irrigated public street landscapes. California is known nationally for its well designed, planted and maintained roads and streets.

Brown's order will bring immediate changes to AB 1881 Water Efficient Landscape Ordinance, California Code of Regulations Title 23, Waters Division 2, Department of Water Resources, Chapter 2.7.

Street Trees and Drought
Urban forest experts of the United States Department of Agriculture have studied street trees across the state and are worried. They report that "10-20% of the urban forest" of a community are street trees planted in some of the "toughest" growing locations in a community.

When planted it is often situated in a space much too small where its roots become static, and the tree fails to grow to its natural mature size

This amounts to over 9 million street trees or one street tree for every four residents. If the 16 million vacant planting spaces were planted with new street trees this resident-tree ratio would be halved. As a result of this vacancy rate street tree density in the 49 communities whose urban forest was used to gather data has declined by 30%. With reduction in the use of water to irrigate streets hundreds of thousands of existing trees may fail. The vacancy rate will increase some more and the cost of filling them with new street trees will be very costly. This is disturbing. Losing trees to drought and lack of irrigation will be tremendous visual loss as well as an economic loss to each community. It is estimated that street trees generate one billion dollars in public services each year. Replacement of lost street trees with more drought resistant trees is estimate to cost 2.5 billion dollars. Californians should be worried about the loss of lonely street trees.

Good News
But the positive spin on the California situation is that our industry is beginning to recognize the importance of sustainable landscape design practices. It is not wise to plant non-native street trees that must be provided with 50 gallons of water a week in order to survive. High water use trees, as defined in the Water Use Classification of Landscape Species database of the University of California, Davis are prohibited according to the updated statewide landscape ordinance (WELO). WELO is pointing the landscape industry toward sustainability by reducing the ETo (evaportranspiration) rate, lowering the maximum applied water allowance, providing incentives for recycling used (graywater) domestic water and encouraging onsite stormwater capture through the use of porous paving, use of micro-detentions, rooftop disconnection and other water harvesting practices. But perhaps the greatest push toward sustainable landscaping is adoption of the sustainable landscape practices set forth in the Bay-Friendly Landscape Guidelines. Counties and cities throughout California use these guidelines to establish and maintain sustainable landscapes. Sustainable landscape design practices for street trees will make the loneliest tree in the city happy.