Gullhög-Tönningfloarna is a large intact hydrological mire complex characterized by fens, bogs, lakes, peatlands, ponds and wet forests. The mires are ecologically complex and remarkably well-developed. The string-flark fens and slightly raised bogs have very well-differentiated strings and hollow structures. The Site supports populations of mire plant and animal species which are important for the maintenance of the biological diversity of the European Boreal region, where rich fens are fairly rare. These fens are important for the species inhabiting such habitat, and offer good conditions for an interesting and rich birdlife. The mire offers valuable feeding places for waders and excellent habitats for nesting species such as the ruff Philomachus pugnax and the vulnerable velvet scoter Melanitta fusca. Nationally red-listed wetland-dependent vegetal communities such as Carex heleonastes and Hamatocaulis vernicosus have also been recorded. The Site is an important water reservoir and plays a vital role in groundwater recharge and carbon sequestration. The main human activities within the area are moose hunting, forestry, fishing, berry-picking and birdwatching. Forestry and peat mining pose potential threats to its ecological character.