The flora of Warsaw may be considered very rich in species on city standards. This is mainly due to the location of Warsaw within the border region of several big floral regions comprising substantial proportions of close-to-wilderness areas (natural forests, wetlands along the Vistula) as well as arable land, meadows and forests. The nearby Kampinos Nature Reserve is the last remaining part of the Masovian Primeval Forest and is protected by law. The Kabaty Woods are by the southern city border and are visited by the residents of southern boroughs such as Ursynów. There are 13 natural reserves in the vicinity and just  from Warsaw, the environment features a perfectly preserved ecosystem with a habitat of animals like the otter, beavers and hundreds of bird species. There are also several lakes in Warsaw – mainly the oxbow lakes at Czerniaków and Kamionek.