Environmental protection is an important topic in Germany and many conservation areas are under special protection.
For this reason, barbecues in public places are not permitted, unless there are specially designated barbecue areas. Smoking and open fire in the open outdoors are generally forbidden (particularly in the summer) in order to avoid the risk of fire. Firewood may not be taken from forests for private use; instead, it must be obtained via purchase (e.g. in DIY stores). Trees may only be cut down after gaining prior permission (at Christmas there are special places where you can cut down your own Christmas tree). Cars are only allowed on marked roads in wooded areas.
There are also certain times of year when dogs must be kept on a lead. It is generally recommended to keep your dog on a lead in the forest so that it is not attacked by other animals or shot by hunters. Moreover, certain areas should not be visited during mating season in order to protect both people and animals. Rubbish may not be disposed of in natural areas; you must take it with you and dispose of it appropriately.
Ducks and pigeons at lakes and in the city centre should not generally be fed. Loud noises should be avoided in natural areas (particularly in nesting season) as this can affect the natural behaviour of the animals.