City of Delaware tree inventory update

The Delaware street tree inven­tory is in full swing again as the weather has warmed up and the leaves have emerged, mak­ing tree iden­ti­fi­ca­tion much eas­ier. The cen­sus is an ongo­ing project that began in 2010 with a key goal of aid­ing the city in main­tain­ing the tree lawn, the grassy area between the side­walk and the street. Accord­ing to David Carey, a mem­ber of the City’s Shade Tree Com­mis­sion, “the tree inven­tory raises pub­lic aware­ness, helps keep tabs on the trees, and helps with planning.”

The data is being col­lected by the Delaware County Mas­ter Gar­den­ers at no cost to the city. The infor­ma­tion being gath­ered for each tree includes the street address loca­tion, its GPS coor­di­nates, the species, trunk diam­e­ter, sig­nif­i­cant health issues, and the pres­ence of over­head wires.

As of Octo­ber 2011, Mas­ter Gar­den­ers had spent 400 hours and inven­to­ried 3,039 trees in cen­tral Delaware. More than half (51 per­cent) of these trees are maples, includ­ing many sil­ver, sugar, Nor­way, and red maples. The other most com­mon tree species are flow­er­ing crabap­ple (7 per­cent), callery pear (6 per­cent), Japan­ese tree lilac (5 per­cent), oak (5 per­cent), and lin­den (4 percent).

Stud­ies have shown that a wide diver­sity of street tree species is a crit­i­cal com­po­nent in help­ing pro­tect against the severe pen­e­tra­tion of pests, such as the emer­ald ash borer or the Long­horned Asian Bee­tle. Pests gen­er­ally are not lim­ited to one cul­ti­var or species, but attack all the trees in the same genus, or fam­ily. There were 1,546 ash trees in Delaware in 2006, when the Emer­ald Ash Borer (EAB) was first iden­ti­fied in the city. Over the past 6 years, this pest has killed or infested nearly all of the city’s ash trees and caused an esti­mated loss in value of the urban for­est of $1 mil­lion. Due to a paucity of funds, only 186 of these ash trees have been replaced. The Asian Long­horned Bee­tle (ALB) has been found near Cincin­nati and is known to attack maple trees. It has not spread to Delaware County, but it is impor­tant that this pest be con­trolled or it could have a major impact on the street trees in cen­tral Delaware.

The City of Delaware is proud of its urban for­est. Every year since 1981, it has been rec­og­nized as a Tree City USA by the National Arbor Foun­da­tion. Cen­tral Delaware has many large, stately trees, some of which are found in the tree lawns. Twenty-two trees in cen­tral Delaware have mas­sive trunks that are greater than 40” in diam­e­ter, includ­ing 15 sil­ver maples.

The data that is col­lected is being shared with the City of Delaware and The Ohio State University’s School of Envi­ron­ment and Nat­ural Resources (SENR). The uni­ver­sity researchers use i-Tree soft­ware to quan­tify the ben­e­fits of urban forests. Accord­ing to Sak­thi Sub­bu­ray­alu, a research sci­en­tist at SENR Urban Forestry, the trees that have been inven­to­ried pro­vide Delaware with $82,484 (aver­age $27.14 per tree) in energy sav­ings (as trees cool in sum­mer and lessen heat loss in win­ter), $86,468 (aver­age $28.45 per tree) in storm water mit­i­ga­tion, $13,131 (aver­age $4.32 per tree) in air qual­ity ben­e­fits, $71,837 (aver­age $23.64) in stored car­bon and $91,298 (aver­age $30.14 per tree) in prop­erty value enhance­ment. In total, cen­tral Delaware’s street trees con­tribute $284,388 (aver­age $93.58 per tree in envi­ron­men­tal ben­e­fits. Big­ger trees pro­vide greater envi­ron­men­tal impact.

There are about 9,000 more trees in the City of Delaware to inven­tory before the cen­sus is com­plete. Susan Logan, the project leader for the Mas­ter Gar­den­ers believes this work can be done in a cou­ple of years, largely due to the increased col­lab­o­ra­tion between the City, OSU, and the Mas­ter Gar­den­ers. Most of the remain­ing trees are in the new devel­op­ments. Chuck Rexrode, the city’s con­tract forester, has doc­u­mented all the trees that have been planted in the devel­op­ments since 1991. Mau­reen Grener, Delaware’s GIS coor­di­na­tor, has been able to gen­er­ate GIS maps of these devel­op­ments, includ­ing the trees. This infor­ma­tion will be pro­vided to the data col­lec­tors, whose main tasks will be to iden­tify, mea­sure, and com­ment on the health of the trees. OSU con­tin­ues to pro­vide the project with PDAs and cus­tom soft­ware to use in col­lect­ing the data.

National Tree Ben­e­fits Cal­cu­la­tor is a free online tool that is avail­able at treebenefits.com/calculator. It can be used to esti­mate the envi­ron­men­tal and eco­nomic value of any tree in the United States, given its loca­tion (ZIP code), species, and size. This cal­cu­la­tor, which was con­ceived and devel­oped by Casey Trees and Davey Tree Expert Co., is also based on i-Tree’s street tree assess­ment tool.

Nancy F. Traub is an OSU Exten­sion Mas­ter Gar­dener volunteer.

Posted by Master Gardener on May 18 2012. You can follow any responses to this entry through the RSS Feed. Comments can be made below.