Klövberget Nature Reserve lies 13 kilometres northwest of Hassela kyrkby, on the border between Gävleborg and Västernorrland counties. It covers 69 hectares, including 46 hectares in Gävleborg. The steep, hard-to-reach parts of the forest have been little affected by logging over the past 250 years, though the forest is not technically old-growth. The reserve’s southern part is in Gävleborg and its northern part in Västernorrland.

The forest is almost entirely spruce, with trees of different ages and open gaps. Many trees have fallen in storms, and almost all the trees in the Västernorrland part were felled. The reserve warns that moving among fallen trees can be dangerous.

The forest floor supports 110 species of vascular plants. Ferns and tall herbs grow in several places, including torta, kärrfibbla and black cohosh. Several red-listed species and indicator species of mosses and lichens are present. The lichen långskägg has one of its largest occurrences in Sweden here. Recorded birds include capercaillie, honey buzzard, lesser spotted woodpecker and black woodpecker. The insect life has not been surveyed, though the reserve may support species of conservation concern among insects and other invertebrates.