Louisville’s urban canopy isn’t as dense as other southern cities’, and many of the big trees the city has have been lost to storms and disease.Citing the health and environmental benefits of a healthy tree population, Mayor Greg Fischer announced today that he’s creating a tree advisory board. The board will be responsible for developing policies to better care for Louisville’s existing trees, as well as planting new ones.The board will be a 12-member committee appointed by the mayor and approved by the Metro Council. Duties will include providing input on tree placement on city-owned property and gathering data about the city’s trees for an annual report. The board will also create a public tree fund with private donations.Fischer says he plans to appoint members of the board before the end of the year.