Biomes: Temperate Deciduous Forest (1989)

[Music] [Music] A biome is a community of living things. the vegetation that develops in a certain climate region and the animal life that has become adapted to it. Of all the major biomes on Earth, the one that undergoes the most changes is the temperate deciduous forest. [Applause] Temperate deciduous forests grow where certain conditions are met. A frostfree growing season of about 5 to 8 months and moderately heavy precipitation which occurs fairly evenly throughout the year as rain or snow. The amount of moisture available and the chemistry and structure of the soil affect which plants survive in this biome. As a result, many different species of trees grow here. Within this diversity, most of the trees have one thing in common. They are deciduous. They grow leaves in the spring, keep them through the summer, drop them in the fall, and stand bare in winter. The temperate deciduous forest biome forms irregular areas in the temperate regions of the world. This is a European forest. Similar but somewhat different plants and animals have similar roles in the North American and Asian forests. Deciduous trees have a profound effect on other plants in their biome. The trees have trunks that spread into an open network of branches. Their leaves are wafer thin and translucent. Because of these characteristics, enough light cascades through the leaves to foster the growth of a shrub layer that contains a variety of woody plants. Below it, the herb layer includes low growing flowering plants. Every forest has these layers. It is light that dictates the rhythm of life in this biome. In winter, when the daylight hours are short, most plants are dormant. But they respond to the longer hours of daylight when spring begins. While the trees are still leafless, sunlight can reach the forest floor. On the bare branches, the tit mouse, who has wintered here, searches for food. Long, delicate cactans appear on the hazel tree. Light triggers the growth of wild flowers that bloom and complete their life cycles rapidly. Blackthorns and other flowering trees bloom. Leaf buds begin to swell, leaves appear, and blue bells carpet the forest floor. As sunlight warms the soil, earthworms move into its upper layers. Here they digest fallen leaves and convert them to a fertilizing humus in their tunnels. Their tunnels airate the soil and help distribute nutrients. Earthworms become an important source of food. Migrating birds like the cuckoo return. Cuckoo feed on oak moth caterpillars. Tit mice also feed on caterpillars. The tit mouse builds its nest in a cavity in an oak tree. From leaf to caterpillar to songb bird, nutrients move up the food chain to a fox. Ground nesting birds are vulnerable to predators. Like the song birds, most animals have their young in the spring. Now, as summer approaches, the canopy of leaves fills in, powered by long hours of sunlight. With the changing hours of daylight, plants like the fox gloves bloom. Insects pollinate many flowering plants. The deer gave birth to its fawn in June. Now, the baby's appetite is enormous. The squirrel is one of the few mammals that live in the trees of the deciduous forest. The sparrow hawk builds its nest high in the treetops. The nuthatch nests lower down. It feeds its young insects pecked from crevices in the tree bark. As the summer continues, butterflies emerge from their chrysalises. On a summer evening, adult badgers come out from their underground homes. They bring out their cubs that were born in the spring. As with all young mammals, play prepares them for adult life. By now, many of the forest creatures have produced their young. These blue tit mouse fledglings are ready to leave their nests. Even though they've taken their first steps to independence, they still depend on their parents for food. As the hours of daylight grow shorter, the rhythms of the forest change. Male deer begin to fight. The dominant buck will mate with the doe's and isolate them from other males. The young will not be born until spring. A new source of food appears. Nuts ripen on trees, supplying food for wood pigeons and other birds of the deciduous forest. Mammals that hibernate in cold winters, like the hedgehog, accelerate their feeding as the growing season ends. Gradually, temperatures begin to fall. In the autumn, berries ripen. Their bright colors make them attractive to birds. More fruit matures. This time, rose hips, which are a major source of food for wood [Music] mice. The days continue to grow shorter. Leaves stop manufacturing the green chlorophyll. Other pigments in the leaves become visible and they take on new colors. Now leaves fall, cut off from their supply of nourishment. Without leaves, the plants lose much less water from evaporation and can better survive freezing temperatures. Dead leaves form a thick layer on the forest floor. Decomposed, they add a large amount of fertilizing humus, creating the richest soil of any forest biome. Millipeds help decompose fallen leaves by eating and digesting them. The woodlouse or pill bug feeds on rotting wood. The first frost has occurred. Winter will soon be here. Shorter hours of daylight are slowing activity in the forest. Little of the food supply remains for animals like the squirrels who winter here and remain active in the deciduous forest. The forest is quiet. Migrating animals have left. Others who hibernate have retreated into shelters. This hedgehog conserves energy during the winter as its body temperature drops and metabolism slows. While the hedgehog hibernates, snow falls in the forest. Those animals who remain active must deal with the cold and the reduced food supply. Birds feathers help to insulate them from the cold. Hidden in the snow are enough nuts and berries to help some animals survive. Rabbits must live mainly on their body fat and on what little plant food they can find in the snow. Predators also find less to eat because so much of their prey has migrated south. And so animals survive in many ways during the winter. When winters are very severe, some animals [Music] die. Eventually, winter comes to an end. Temperatures [Music] rise. The hours of daylight increase. [Music] Finally, on the bare branches, leaf buds that laid dormant all winter begin growing into leaves, and the forest floor is covered with a new growth of plants. The cycle of the seasons continues as spring returns to the deciduous forest biome. [Music]