The legal basis for this category of protection is the Federal Nature Conservation Act (in conjunction with the Lower Saxony Implementation Act). Section 28 of the Federal Nature Conservation Act states:
Natural monuments are legally established individual creations of nature or corresponding areas of up to five hectares whose special protection is required
- for scientific, natural history or regional history reasons or
- because of their rarity, uniqueness or beauty.
Similar to nature conservation areas, natural monuments are also subject to an "absolute prohibition of change", i.e. the ordinance does not have to prohibit any specific actions that lead to an impairment of the protected object. However, measures to avert danger are exempt.
There are 20 natural monuments in Salzgitter, all of which, with the exception of one spring, are individual trees or groups of trees.