The lake is surrounded by one of the biggest broadleaf forest in Stockholm rich in various species of birds, batrachians, and bats.

[1][2] Historically considerably larger, Kyrksjön used to extend well into the Spånga parish and its outflow used to discharge through a nine metres tall white water.

Aquatic plants are relatively few, the lake floor is mostly covered by Charales such as Chara tomentosa (present since the mid 19th century), accompanied by bladderwort, milfoils, and others.

Bottom specimens taken in July 1996 mostly unveiled larvae of chironomids, Oligochaeta, and empty shells - typical for lakes rich in nutrients but poor in oxygen.

[2] The dense vegetation surrounding the lake contains nightingales, blackcaps and marsh warblers hiding from sparrowhawks, goshawks, and tawny owls.