Plants are not part of the food chain in polar regions. Why is this so?

It will be cold and it will be difficult for the plants to even grow !

Plants receive little to no sunlight in the winter months of the polar regions, it’s also extremely difficult to sustain plant life in a location with little to no good soil and harsh freezing temperatures

This is all you, but i can give you some topics that you could try. if it rained when you want to do something outdoors, it 'limits' that human activity. maybe you want to do an experiment that goes throughout the whole year and you have to have above freezing the entire year. this 'limits' your activity. i thought of those just off of the top of my head. something that gets to me that might be getting to you is you are thinking too hard about what to do. think simply, and if it is too simple, then bump it up just a little bit.