Six scientists will take part in “Three Towns, One Forest,’’ a regional environmental forum taking place April 25 at Lesley University. The panel will discuss the conservation value and future of the state-owned Alewife Reservation and the silver maple forest in the adjacent Belmont Uplands, which extends into Arlington and Cambridge. With climate change in mind, the speakers will focus on the state Wetlands Protection Act’s regulations, and hydrological concepts that could be used to preserve the silver maple forest and its surrounding floodplain in the Mystic River watershed. Community initiatives will be suggested to preserve these resources. The public forum will be held at 7 p.m. in the University Hall amphitheater, 1815 Massachusetts Ave. in Cambridge.