City Trees is a premier publication focused on urban + community forestry. In each issue, you’ll learn how to best manage the trees in your community and more!
Issue link: https://read.dmtmag.com/i/65193
has compacted soils, and the wetting agent allows water to penetrate Savannah's compacted sandy soils. The delivery of water to the trees is key in dealing with the drought. About 90% of the trees that are planted within a given year on the City's right-of-way do not have any irrigation. For those trees, we use three water trucks with 250-gallon (946-liter) tanks in the bed to deliver water. In addition to the three watering trucks, we have an additional 250-gallon tank on a trailer and we have a 750-gallon (2839-liter) tank that can be installed quickly in back of a large dump truck. We use these two other tanks during the hottest part of summer for any trees showing signs of drought stress. We purchased these items over the years while the economy was going well; plan and budget now for the worst-case scenario! We can also manage with the drought by varying the number of trees we plant in a year. We know how many trees a crew can water in a day; with that information, we plan how many trees we should plant for the year in order to have a good survival rate. We arborists have many tools at our disposal and in my opinion, planning is the greatest tool you can use in battling the drought. —Michael W. Pavlis, Tree Maintenance Supervisor, City of Savannah, Georgia The City of Santa Clarita, California is from the Pacific Coast, and nestled in the north end of Southern California's Los Angeles County. Sitting at 1,200 feet (366 m) above sea level, the region histori- cally experiences a dry climate with an average rainfall of 17 inches (432 mm) per year. Currently, the drought in California is less extreme than that of Texas. Santa Clarita's water sources consist of near equal amounts of ground water and imported water from the statewide aqueduct system. As a result, the impact to the com- munity is lessened; however, residents conserve water to avoid the possibility of rationing. located in the Santa Clarita Valley, 30 miles (48 km) Santa Clarita is home to many large native trees, includ- ing the valley oak (Quercus lobata), coast live oak (Q. agrifolia), California sycamore (Platanus racemosa), and the cottonwood (Populus fremontii). Many of the native trees prefer alluvial soil and do best near riparian areas, or where ground water is available. Some of the drought- resistant non-native tree species selected for use in Santa Clarita include the African sumac (Rhus lancea), Chinese pistache (Pistachia chinensis), crapemyrtle (Lagerstroemia sp.), mesquite (Prosopis sp.), paloverde (Parkinsonia aculeata), and Eucalyptus species. Property owners are responsible for watering trees grow- ing in residential parkways and rights-of-way, while the City maintains those growing in parks and along major roadways. Trees growing in non-irrigated parkways are closely monitored, and mulch is continually added to tree 24 wells to ensure a higher volume of moisture retention in the soil. Of the estimated 45,000 trees maintained by the Santa Clarita's Urban Forestry Division, approximate- ly 1,200 trees require supplemental watering by a water truck for establishment and ongoing survival. As water is a precious commodity in the City of Santa Clarita, its use is not treated lightly. The City's Urban Forestry Division is mindful of this concern each time a tree is planted. Tree selection is based on drought and temperature tolerance, as well as tree site locations. These considerations are critically important, but water is the living factor that will determine if the tree suc- ceeds or fails for the resident and for our community. —Robert Sartain, Urban Forestry Supervisor, Public Works Department, Santa Clarita, California Texas is one long drought broken by an year in recorded history. We saw a bit of reprieve over the winter, but the drought for much of the state is fore- cast to persist or intensify. Our communities are dealing with a widespread natural disaster; it is estimated that 5.6 million trees have perished in Texas communities. occasional flood. 2011 was the hottest and driest The Houston area was hit particularly hard last year. So far, we have documented over 50,000 public trees that have been removed at a cost of approximately $10,500,000. This alone represents $1,000,000 a year in lost environmental services. It would cost over $10,000,000 to replace these trees with 3-inch- (76- mm) caliper trees. There are parks in Houston where 90% of the trees have died. San Antonio completed a major tree planting initia- tive during 2011—and keeping those trees watered was tough. The combination of Treegators, many water trucks, and a dedicated staff have made the difference for these new trees but have reduced the number of additional trees that we have been able to plant and care for. We are also seeing an increase in stress- related diseases such as hypoxylon canker. There will be many public and private trees removed this year. Gazing deep into the crystal ball, we need to plan for hotter and drier years. Adjusting our recommended plant palette, planting season, and maintenance speci- fications are just a few changes we will have to enact. We tree people have been pushing fall planting, but not effectively. I think the drought gives a good solid reason to concentrate on fall planting because most tree root growth occurs when the leaves are dropping in the fall and right before they grow in the spring. Following that logic, the best time to plant is between Halloween and St. Patrick's Day. Not planting trees isn't the answer. More Trees, Please! —Paul Johnson, Regional Urban Forester, Texas Forest Service City Trees