REVERE – None of the students could guess the acronym for DCR, but they all knew the benefits of the trees they helped state and city officials plant Friday to launch an effort to increase Revere’s tree canopy by 10 percent.”Oxygen!” “Shade,” students answered when asked the benefits of trees.”Great answer!” Energy and Environmental Affairs Secretary Matthew A. Beaton replied. “I ask all of you to take this opportunity ? we need to tell as many people as possible that this program exists, and spread the word and contact the city or Department of Conservation and Recreation (DCR) to help get the word out that folks want a tree and want to be part of the program.”Beaton, Mayor Dan Rizzo, Massachusetts Speaker of the House Robert DeLeo, State Rep. RoseLee Vincent, State Sen. Anthony Petruccelli, DCR Commissioner Carol Sanchez and employees, and fifth-graders at the Beachmont Veterans Memorial School gathered Friday morning to plant an American elm, a post oak, a red maple and a linden tree behind the school at Fredericks Park.The tree planting ceremony marked the expansion of the Greening the Gateway Cities Program to Revere. The program targets the Commonwealth’s 26 Gateway Cities and uses tree planting to reduce energy use in high density urban neighborhoods and lower heating and cooling costs for residents and businesses. The goal is to increase the urban tree canopy by 10 percent in selected neighborhoods. Beaton said such action will save the average homeowner approximately $230 a year in heating and cooling costs once the trees reach maturity. The trees also reduce stormwater runoff, improve air quality, increase property values and tax receipts, and promote a safer and healthier environment, according to Beaton.The program is spearheaded by the DCR and has so far led to the planting of 2,000 trees in Chelsea, Fall River and Holyoke. This June, local workers in Revere and Chicopee will plant 100 trees.DeLeo said that attention to Revere’s natural resources has led to a revitalization of the city. But he also noted that green space remains under immense pressure.”As a former selectman, but more importantly a citizen in this particular area, I know too often the benefit of open spaces, gardens and playgrounds that are often overlooked,” DeLeo said. “With projects like today’s, we change that. We give our children a greener place to play, and a more welcoming place for families and friends to come together.”And it’s a welcoming place for politicians and students to come together, too, as students and legislators grabbed shovels to place dirt around an American elm.”I’ve never planted a tree before – but I plant my mother’s flowers for Mother’s Day,” said student P.J. Mundis.Rizzo said the program was particularly beneficial because of last summer’s tornado.”It tore up not only buildings, houses and infrastructure, but the lion’s share of trees,” Rizzo said. “There couldn’t be a more timely program that the City of Revere is involved in.”