Hey there! I'm happy to help!
Producers are organisms that produce their own food and energy. In most ecosystems these are usually just plants. Some plants like the Venus fly trap are not producers because they consume bugs, which are other organisms.
Consumers are organisms that eat other organisms to obtain food and energy. These are usually animals that eat plants or other animals.
Decomposers are organisms that break down animals remains and waste to gain energy. These are usually bacteria and fungi.
So, we can make the following list.
Producers: Wild grasses, alpine plants, fallen trees, (these are all plants)
Consumers: Mountain goat, eagle, hare (these all eat other organisms)
Decomposers: Lichens, mosses (these are decomposers).
Mosses could be a producer but they have the unique capability of breaking down organic matter, so it seemed for fitting to put them in the decomposer category.
Have a wonderful day! :D
