Being that they are on the border between Soho and Noho, these 2-x-4’s nailed around trees boxlike might have some people guessing that they are some sort of public art project. But in fact they are protection from a project of a more practical sort, one that will take 2 1/2 years, namely the reconstruction of Houston St. between the Bowery and West St. The project, which started Aug. 1, will replace sewer lines and water mains and resurface the street. Feeling the community is largely uninformed about the work, Community Board 2 is asking the Department of Design and Construction to hold regular informational meetings to give project updates and for project information to be posted on the D.D.C. Web site.