Trees play an important role in the carbon cycle because

Forests exchange large amounts of CO2 and other gases with the atmosphere and store carbon, in various forms, in trees and soils. ... Much of the CO2 in the air above a forest is taken in by trees through the process of photosynthesis,where it becomes one of the building blocks fortree growth or energy for life. (i hope this can help you ):)

Balkan nationalism increased tensions between austria and russia

They must use the scientific method