Plant transition for winter
During the winter the taiga is covered with a foot (30 centimeters) or more of snow. The conifers that dominate the taiga deal with the snow and cold temperatures in their own way. The trees are nearly unaffected by the temperature. Their major threat during the winter is lack of water. Most trees lose moisture because of evaporation through their leaves. Their only source of water is absorbed through their roots in the ground. When the winter comes, and the ground is frozen and covered in snow, the leaves continue to lose moisture, but the root cannot absorb water from underground. Many trees can die when sufficient amounts of water are not absorbed through the roots. The lack of water that reaches the ground is called a winter drought. Conifers, however, have diverted this threat by developing needles that keep moisture in. The needles are smaller than typical leaves and lose little water from evaporation. They are also waxy which also helps to hold the water in. Their waxy, round, and tapered, needles also promote the shedding of snow, unlike leaves. This prevents branches from breaking off because they do not collect heavy snow. These adaptions help conifers survive during the long winter droughts.
Plant transition for spring
In the spring plants in the taiga come back to life. As the snow melts off of the conifers and hits the ground, the moss below is watered and comes out of its dormant state. Because both conifers and moss keep their leaves during the winter, as soon as either the sun comes out or temperatures rise above freezing, they begin growing and making energy in a process called photosynthesis. During this process, sunlight combines with carbon dioxide and water to make glucose. Glucose is the energy-producing agent for most plants and all of its life processes. Moss starts photosynthesis in late spring after its leaves are rehydrated again. In the winter the plant dries out to avoid its tissues from freezing. In the spring the plant comes out of its dormant state after it is hydrated by the melting snow.
Plant transition for the summer
Plants take advantage of the long hours of sunlight in the summer and grow very quickly in bogs and marshes. Trees grow tall and fast by using photosynthesis.
Plant transition for the fall
In the fall trees change color, such as the birch and aspen which turn yellow. The color change is a sign that they are beginning to shut down for the winter.