Terraforming Mars

If I play an event card that removes plants and I'm the only one with plants, do I have to remove my own plants?

Effects that remove your own resources are mandatory, while effects that remove resources from any player (marked by a red border around the resource icon) are voluntary and may be performed in full, in part, or not at all. Only one player or card may be targeted at a time with the effects of a card. Removing production is always mandatory.