In which of the following scenarios is lightning protection deemed necessary?

Lightning protection is deemed necessary for historic trees due to their significant value and potential vulnerability to lightning strikes. These trees often possess unique characteristics, age, and cultural importance that warrant special care and protection. A lightning strike can cause severe damage, not only threatening the tree's health and stability but also potentially harming the surrounding environment or structures of historical significance.

In contrast, small ornamental trees, flowering shrubs, and indoor plants generally do not represent the same level of risk or value that necessitates dedicated lightning protection measures. While these plants certainly deserve care and attention, they are typically not as critical to preserve as historic trees. Therefore, the need for lightning protection is primarily justified in the context of historic trees, which require safeguarding to maintain their existence and the historical heritage they represent.