Look I am not even close to a genius in this type of stuff but the leaves help collect energy and sunlight for the plant to live off of during the winter. It basically needs them for processing and helping them with their food. Also food is stored in every pine needles mitochondrion or the powerhouse of their cell structure. In the mitochondrion their is things like chloropasts. These are like the energy or food for the cell. So when the tree cant draw nutrients from its roots or soil anymore all the excess things stored in the pine needles will help the tree survive.
The trees in the taiga region don’t get much sunlight. So they have to maintain their green needles year-round so they can use photosynthesis to make enough energy.
