The Vian polders and floodplains is a nature reserve south of Vianen. The Bolgerijen and Autena polders form the largest inner dike grienden complex in the Netherlands. The grienden in the area alternate with hay meadows, pastures and poplar forests.
Some of the willows are cut down by Utrecht Landscape to preserve the special flora and fauna. Burrowing owls such as the little owl live in hollow willows, while oak ferns and various species of moss grow on the willows. The insects present are a food source for buzzards and kestrels.