This wetland grew when debris partially blocked one of the culverts under the rail trail. As the water rose, the roots of the dead trees you see could no longer exchange oxygen in the soil—they suffocated and the trees died. This is the same natural process that occurs when beavers build a dam on a stream and flood the surrounding vegetation. The resulting ponds produce a new type of habitat for new types of plants and animals. Diverse habitats on a landscape make it more resilient to change.