The Study of Ecosystems

Ecology

Chapter 47 The Biosphere

47�1 Earth: A Living Planet

Ecology

� “The study of the interactions of organisms with one another and their physical surroundings.”

� Biotic - living organisms� Plants, animals, fungi, micro-organisms

� Abiotic – non-living factors�Water, soil, air, rocks, sunlight, weather

� Living vs. non-living vs. dead.

Biosphere� “The part of the Earth where life exists.”

� Biosphere includes:

�Atmosphere – Air

� Up to 8 kilometers above the surface

�Hydrosphere – Water

� 70% of Earth Surface

�Lithosphere – Ground/surface

� Over 8 kilometers below the surface

Ecosystems

� “A given areas physical features [abiotic] and living

organisms [biotic].”

� Living things in an ecosystem are referred to as a

community.

� An ecosystem can be smaller than a drop of water.

Ecological Succession� The gradual change from one ecological community

to another.

� This process can take several decades to thousands of years.

� Stages of Succession

� The first organisms are called “pioneerpioneerpioneerpioneer” species.

� These are able to survive in the full sun.

� Next are various “intermediateintermediateintermediateintermediate” species.

� These survive in a mixture of sun and shade.

� Final stage is called “climaxclimaxclimaxclimax” species.

� These survive in shade in the early stages.

Wildlife Use of Various Stages of Land Cover Type

Old-field Succession Showing Changes of Vegetation and Wildlife

A Biome: An environment that has a characteristic climax community.

Biomes

47-2 Land Biomes

Two types: Land and Aquatic

Land Biomes are named for the dominant climax plant community

World Biomes

1. Tundra: Northernmost land Biome

�Nearly treeless, most trees are only 2 – 3 meters tall

�Migratory animals�Elk, caribou, wolves, ptarmigan

�Permafrost – permanently frozen subsoil�Lots of stored carbon

2. Taiga: Coniferous Forest� Conifer trees [cone bearing]

� Spruce, pine, fir, redwood� Up to 60 meters tall

� Ground thaws in the summer

although not for long in some places

� Many animals hibernate or migrate during the winter� Black bear, moose, grouse

3. Temperate Deciduous Forest� Plants that lose all their leaves in the fall

� Oak, maple, beech� The amount of leaf litter provides nutrients for future growth

� Changing seasons� Temperature and length of daylight trigger cells to harden and then leaves to drop; protection from water loss when ground is frozen

� A great variety of seed plants provide food for many species of animals

4. Grassland:

¼ of Earth’s land surface� Prairies, plains, savannas, pampas, steppes

� Two types – tropical and temperate� Tropical – close to the Equator : hot all year

� Varies from very wet to very dry

� Temperate – hot summers and cold winters� Great Plains

� Animals include herbivores and the carnivores that feed on them� Bison, wildebeests, wolves, lions

5. Tropical Rain Forest� Year-round temperatures above 250 C : 200 – 400 cm of rainfall

� Contain more species [fungus, bacteria, plants and animals] that all the rest of the land biomes combined

� Warm temperatures and wet conditions cause decomposition at a very fast rate. Rainforest soils are not very thick so tall plants must find ways to support themselves.

� Disappearing at a rate of 100 acres per second

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