How do deciduous trees protect themselves during the seasons?

Deciduous methods: First thing they do is take mobile nutrients out of there leaves and move them into the root system for storage and use next year.

Dropping the leaves helps them shed ice and snow so that weight doesn't build up and snap off limbs.

Methods common to conifers and deciduous:

Removing excess water lowers the chance of having enough freeze and expand breaking the stem.

Removing impurities and air bubbles from the water. Ice usually forms around and a speck of dirt (nucleus) at 0 degrees Celsius but if there is no nucleus ice will not form till -37 (non-nucleic freezing).

The internal clock of the tree and responses to its environment will has a great effect of the survivability of the tree as well ie coming out of dormancy to soon, hydrating then freezing with the next cold snap.

I believe there's others but that's all I remember. Theres lots of summer time protection methods as well I assume you just want the winter ones...