City of Delaware tree inventory

You may have noticed peo­ple on the streets of Delaware hold­ing PDAs and mea­sur­ing street trees. The data col­lec­tion is being done by the Delaware County Mas­ter Gar­dener Vol­un­teers as part of a project to inven­tory all the street trees in the City of Delaware.

Pam Ben­nett is the Ohio Mas­ter Gar­dener Coor­di­na­tor and a strong advo­cate of the street trees project. She says that Mas­ter Gar­den­ers have been involved in more than 15 street tree inven­to­ries at var­i­ous loca­tions across the state, includ­ing Spring­field in Clark County where Pam is also an OSU exten­sion agent. She sees these efforts as a way to imple­ment the Mas­ter Gardener’s envi­ron­men­tal hor­ti­cul­ture ini­tia­tive and the projects tie in directly with OSU’s focus on “Why Trees Matter.”

The Street Tree Com­mis­sion in the City of Delaware is com­prised of nine vol­un­teers. It is the gov­ern­ing body that over­sees the street trees. Accord­ing to Chuck Rexrode, a retired USFS research ento­mol­o­gist who has worked as Delaware’s con­tract forester for more than 20 years, there are more than 12,000 street trees in the City of Delaware. This includes nearly 2,800 trees in the cen­ter of the city. New devel­op­ments, which sprang up dur­ing what Chuck calls the “Golden Age” (between 1995 and 2005) account for about 10,000 trees. In total, Delaware’s trees are val­ued at about $15 mil­lion, with many of the most mature and valu­able spec­i­mens located in the cen­tral city.

Accord­ing to David Carey, who serves on the city’s Shade Tree Com­mis­sion, “the tree inven­tory raises pub­lic aware­ness, helps keep tabs on the trees, and helps with plan­ning.” He adds that elec­tronic records will pro­vide the con­ti­nu­ity nec­es­sary for the suc­cess­ful imple­men­ta­tion of the city’s long-term street tree main­te­nance pro­gram, which has been cut back in recent years due to bud­get constraints.

To help facil­i­tate the street tree inven­tory project, Davis Syd­nor, Pro­fes­sor of Envi­ron­ment and Nat­ural Resources, and Sak­thi Sub­bu­ray­alu, a research asso­ciate in the School of Envi­ron­ment and Nat­ural Resources, pro­vided back­ground on the project and the process. Sak­thi also cus­tomized i-Trees soft­ware pack­age for the Delaware County Mas­ter Gar­den­ers who are doing the data col­lec­tion. The City of Delaware Infor­ma­tion Tech­nol­ogy Depart­ment pro­vides detailed sec­tion maps.

Mas­ter Gar­den­ers, spear­headed by vet­eran Mas­ter Gar­dener Susan Logan, use PDAs to record sev­eral attrib­utes for each tree, includ­ing the street address, GPS coor­di­nates, tree species, and its diam­e­ter at breast height (DBH). This data is uploaded to a com­puter. The infor­ma­tion is also sent to a data­base main­tained by The Ohio State Uni­ver­sity for use by their research staff. i-Trees soft­ware uti­lizes a model that quan­ti­fies the ben­e­fits of a tree using the species and DBH to get an idea of the canopy vol­ume. In addi­tion to the beauty and enhanced prop­erty value trees offer, i-Trees cal­cu­lates the sav­ings from an energy stand­point, storm water mit­i­ga­tion, air pol­lu­tion ben­e­fits and car­bon cap­ture or sequestration.

Sak­thi has coau­thored sev­eral reports ana­lyz­ing the street tree data already col­lected in four Ohio com­mu­ni­ties, West­er­ville, Dublin, Toledo and Yel­low Springs. Accord­ing to him, the stud­ies have shown that most of their trees are smaller in order to accom­mo­date being under power lines. Con­versely, from an envi­ron­men­tal impact view­point, he notes that we need larger trees. Chuck Rexrode agrees with his analy­sis. He says that trees that mature at a rel­a­tively short height are planted to avoid “top­ping” by power com­pa­nies that can dis­fig­ure the tree. The Tar­ter­ian and Tri­dent maples are two trees that only grow to 18 feet and fit well under high volt­age wires. How­ever, because the city code requires that branches have 8 feet clear­ance over the side­walk and 14 feet clear­ance over the street, that leaves a neg­li­gi­ble tree canopy. While Japan­ese lilac trees and ser­vice­ber­ries are two other trees that Chuck rec­om­mends for plant­ing under power lines, he also notes that they pre­fer after­noon shade.

Uni­ver­sity research has also found that diver­sity at the cul­ti­var and species lev­els are gen­er­ally good. How­ever, accord­ing to Sak­thi, at the genus (fam­ily) level, the diver­sity is lower. For instance, in Toledo, 50 per­cent of the street trees are maples. This could be a prob­lem, since pests gen­er­ally are not lim­ited to one cul­ti­var or species, but attack all the trees in the same genus. The Asian Long­horned Bee­tle (ALB) is a newly iden­ti­fied pest in Ohio. It has been found near Cincin­nati and is known to attack maple trees. With half of the street trees in Toledo being maples, accord­ing to Sak­thi, that city could face a major prob­lem, if the pest is not con­trolled and attacks Toledo’s trees. Chuck esti­mates that 30 per­cent of the trees in the City of Delaware are maples.

The Emer­ald Ash Borer (EAB) has hit the large major­ity of the ash trees in the City of Delaware since it was first iden­ti­fied in the city in 2006. Accord­ing to Chuck, there were 1,546 ash trees in the city five years ago. After the city com­pletes the planned removal of 397 trees this win­ter, only 284 ash trees will remain and more than 90 per­cent of those trees are already infested with EAB. David Tidd, the for­mer Parks & Urban Forestry Divi­sion Super­vi­sor for the City of Delaware, applied for a cost-shared grant for ash tree replace­ment that enabled the city to replace 100 trees in 2011. How­ever, only 129, or about 10 per­cent, of the 1,262 ash trees that have been removed have been replaced.

EAB has already cost the city about $1 mil­lion and the total cost is expected to reach $1.3 mil­lion before the EAB is com­pletely elim­i­nated from the local street trees.

Dave Carey is proud of how “the City, the Street Tree Com­mis­sion, OSU exten­sion, and the OSU Depart­ment of Forestry are work­ing together to get this done, and it’s not cost­ing the city any­thing.“ His goal is ulti­mately to have the street tree data­base acces­si­ble to the pub­lic, so they can know the value of their trees.

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

Posted by Master Gardener on Sep 23 2011. You can follow any responses to this entry through the RSS Feed. Comments can be made below.