Règle correspondante
Switzerland
Practice Relating to Rule 147. Reprisals against Protected Objects
Section E. Natural environment
Switzerland’s Basic Military Manual (1987), in the part dealing with “Hostilities and their limits” and, more specifically, in a provision regarding the prohibition of the taking of reprisals against the civilian population, refers, inter alia, to Article 55 of the 1977 Additional Protocol I. 
Switzerland, Lois et coutumes de la guerre (Extrait et commentaire), Règlement 51.7/II f, Armée Suisse, 1987, Article 25(2).
The manual further states, with reference to, inter alia, Article 55 of the 1977 Additional Protocol I: “By virtue of the Geneva Conventions and their additional Protocols, [reprisals] are prohibited with regard to … the environment”. 
Switzerland, Basic Lois et coutumes de la guerre (Extrait et commentaire), Règlement 51.7/II f, Armée Suisse, 1987, Article 197(2).
Switzerland’s ABC of International Humanitarian Law (2009) states:
Means and methods of warfare
Even in war not everything is allowed. Various means and methods are prohibited, including … Reprisals against the civilian population or against non-military objectives[.]
Reprisals
International humanitarian law does not include any general prohibition of reprisals. There are however numerous provisions that prohibit specific types of reprisal … Also prohibited are reprisals against certain specific objects such as … the natural environment[.] 
Switzerland, Federal Department of Foreign Affairs, ABC of International Humanitarian Law, 2009, pp. 29 and 37.