Related Rule
Ukraine
Practice Relating to Rule 44. Due Regard for the Natural Environment in Military Operations
Ukraine’s IHL Manual (2004) states:
2.3.5.3. If combat is conducted in the mountains it is necessary to take into account the probability of rockslides, snow avalanches, and cloudburst floods that are likely to endanger persons and objects protected by the laws of war …
2.3.5.4. If combat is conducted in the forest, it is necessary to take into account the probability of forest fires that are likely to endanger persons and objects protected by international humanitarian law. 
Ukraine, Manual on the Application of IHL Rules, Ministry of Defence, 11 September 2004, §§ 2.3.5.3–2.3.5.4.