You study forestry and want to write about ecotourism. That's easy. Try to rely on forestry eco-tourism. Write eco-tourism with the basic theory and skills of forestry. Write about the significance of forestry to the development of ecotourism (it can be specific to some aspects or points).
In this way, you not only used your forestry knowledge, but also wrote your favorite eco-tourism, and the idea of this paper is quite unique and novel. It has both theoretical research value and practical guiding significance. You can talk to your tutor about your ideas and see what he thinks. If he agrees, you can write; If you don't approve, then write forestry in a down-to-earth manner. After all, the tutor is the key point of whether the paper passes or not.