Ed Golson Outdoor Education

phenology

I'm sure you have noticed by now that the weather changes as the months go by. The weather is cold and snowy in winter and hot and dry in the summer. Have you ever stopped to think about how the changes in the seasons affect living things in the wild? Well, these changes have a huge impact on how wild plants and animals live and interact with their environment. The study of how changes in the seasons and weather affect living things is called phenology.

People that study phenology look for clues to see how the environment is changing over time. They look for clues in the blooming of flowers, migration of birds, changing of leaves, and many other natural events that repeat each year. By looking at how things change from season to season and from year to year, scientists can study how plants and animals interact and how climate changes affect all living things.

Next time you have the chance, go outside and look around. Watch and listen to the environment. What clues can you find that tell you what season we are in without using the weather?


The following is just a brief sample of some of the ways the living parts of the environment change and adapt as the seasons change.

        (Skip to a season: Spring / Summer / Autumn / Winter )

Spring :
Spring is the season of birth and renewal; winter's cold has finally ended. There is now enough sunlight and liquid water from the rains and melting snow for the plants to start growing again. Plants have to be careful. If they bloom too early, a late frost could come and kill all the buds. If they wait too long however, they risk falling behind and getting shaded out (not having enough light to grow) by the taller and faster growing plants. Short plants in the woods have to time things just right so that this doesn't happen to them.  Many types of special flowers will try to sprout, bloom, and die before the trees have a chance to shade them out. These types of flowers are called spring ephemerals.  An example of these types of flowers are blue violets.

For animals, spring is all about finally having real food again and not having to worry about freezing to death. Smaller animals like amphibians and rodents come out of hibernation. Migratory birds come home. Mammals start to lose their heavy winter coat and start to grow their summer coats.

    ( Back to top )

Summer :
Summer is the brightest and warmest time of the year. It is a time of growth. Sunlight abounds giving plants all they can handle. Animals greedily eat as much of the new plant growth as possible. For the most part, life is good.

Summer has it own set of problems, however. Summers can get very hot and dry. Both plants and animals can struggle to find water if the sources dry up.  In order to conserve water, plants will close their leaves to prevent water from evaporating out of them. Unfortunately, this also prevents the plant from undergoing photosynthesis to make sugar, but that is the price they have to pay.

Animals also have to work harder to conserve water. Many animals will simply try to find more juicy fruits and leaves, but that doesn't work when they are not available. Some animals will find a shady spot and not move at all during the hottest parts of the day in order to keep cool. Some animals will migrate several miles to find a lake or a stream to drink from. Summer is a time of growth, but it can also be a time of stress and hardship.

    ( Back to top )

Autumn :
Autumn is a time for getting ready. The good times are coming to an end. Those plants and animals that don't prepare for winter won't make it to spring. Deciduous trees start getting rid of their leaves because they won't be useful in the winter. As the tree cuts off the supply of nutrients to the leaves, the green chlorophyll starts to break down. As this happens, the red and yellow pigments that are in the leaves become more visible. Many plants also start releasing their seeds in the autumn. Most seeds are hard and have a thick covering so they can survive the winter frosts. That way, when spring comes along, the plants have a new generation ready to go.

Animals also need to prepare for the winter. Many animals, like rodents, birds, and deer fill up on all of the available seeds and fruits. Almost all animals need to fatten up before winter to make sure they have enough energy to make it through the winter. Mammals grow their winter coats and put on extra fat as insulation. Migratory birds like geese and many songbirds begin their long migration south during the fall. They prefer to fly to greener areas than try to rough it out through the hard winters.

    ( Back to top )

Winter :
Winter is a harsh season. It is bitterly cold, windy, and dark. Food is much harder to come by for both plants and animals. The little water that is around is mostly frozen making it nearly useless to most living things. Life is hard, but all living things have ways to adapt.

Most plants go dormant during the winter. They just stop trying to undergo photosynthesis. It simply isn't worth it. There isn't enough sunlight or liquid water for most plants. That's why the trees got rid of their leaves in the fall. If they hadn't, all the water in the trees would evaporate through the leaves before they could make any real sugar. The tree would then become dehydrated and die. Coniferous trees, like pine or spruce, avoid this problem by having specialized leaves (their needles) that are smaller and better protected against the drying and freezing affects of winter's chill. That way, anytime during the winter that there is a slightly warmer and sunnier day, they can take advantage of it by using their leaves to make sugar when the rest of the plants can't.

Animals also need to adapt to the winter. Smaller mammals and all cold-blooded animals like amphibians and reptiles go into hibernation. These animals just dig a hole or den and sleep through the winter. Their body slows down so that they don't need to wake up to get food or water. Larger animals often just tough it out. They eat all the food they can and often group together to stay warm.

It's a hard season, but soon spring will be back and the whole process will start again.

   ( Back to top )

Back to Previous Page