Kungsfors Nature Reserve covers 26 hectares between Jädraån and Lillån, 5 kilometres northwest of Järbo. Its forests include broadleaf trees and coniferous woodland with a high share of deciduous trees. Visitors can walk the trails. The reserve map shows trail markings, parking and a rest area with a place to grill.

Both waterways have cut deep into the ground, forming steep ravines. Lillån winds through sharp bends, creating cut-off pools known as oxbow lakes. These pools are sometimes flooded and sometimes dry.

Small-scale grazing, haymaking and tree felling shaped the forest. The result includes old, large broadleaf trees and dead deciduous wood, which provide habitat for species that depend on old broadleaf trees. Examples found in the reserve include aspen feather-moss, grynig gelélav and large aspen bracket fungus. Cycling is possible on some trails in Kungsberget and Kungsfors nature reserves, but cycling off the trails is not allowed.