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Unit 4: Ecosystems // Visuals

Animation(s)

Common vs. rare tree species
Common vs. rare tree species
On the rainforest plot of Barro Colorado Island, common tree species account for only 15% of the total tree population compared with 80% of the total tree population in a typical New England forest. View animation

Rainforests
Rainforests
Rainforests cover only 6% of the planet but are home to over half of the Earth's plant and animal species. View animation

Return of the wolf
Return of the wolf
Since the return of the wolf, the elk population has drastically decreased from 20,000 in the 1990s to less than 10,000 today. View animation

Photograph(s)

African fish eagle
African fish eagle
The African fish eagle is a counterpart to the American bald eagle and fills the same ecological niche in areas where it is present. View image

Automeris moth
Automeris moth
When the Automeris moth perceives a threat, it moves its forewings to reveal false eye spots on its hindwings and to frighten predators away. View image

Predators impose top-down control on ecosystems
Predators impose top-down control on ecosystems
Since they were reintroduced to Yellowstone National Park in 1995, gray wolves have reduced the number of elk and other prey species, with impact further down through the park's food web. View image

Tropical ecologist Stuart Davies in the field
Tropical ecologist Stuart Davies in the field
Director of the Center for Tropical Forest Science at the Smithsonian Tropical Research Institute, Stuart Davies explains the symbiotic relationship between ants and a cecropia plant. View image

Graphic(s)

Biome type in relation to temperature and rainfall
Biome type in relation to temperature and rainfall
Biome distribution is closely associated with climate. Each of the biomes shown in this figure represents a different combination of temperature and precipitation ranges. View image

Earth's major land biomes
Earth's major land biomes
Biomes are Earth's major habitat types. They are classified according to the predominant forms of vegetation that they support. View image

Earth's marine and freshwater biomes
Earth's marine and freshwater biomes
Marine and freshwater biomes contain many different types of habitats, from forest bogs to abyssal zones in the deep oceans. View image

Energy and nutrient transfer through ecosystems
Energy and nutrient transfer through ecosystems
Nutrients (shown by light arrows) cycle through ecosystems in a closed loop, while energy (shown by dark arrows) is released at each stage. View image

Lake Michigan food web
Lake Michigan food web
Food webs illustrate the complicated feeding patterns within ecosystems, in which a single species may consume a variety of other creatures and in turn serve as prey for multiple predators. View image

Ocean net primary productivity, 1997-2002
Ocean net primary productivity, 1997-2002
In contrast to land, where vascular plants carry out most primary production, most primary production in the oceans is done by microscopic algae. View image

Plant species diversity
Plant species diversity
Many hypotheses have been proposed to explain why species richness is greater in tropical latitudes than near the poles. View image

Terrestrial net primary productivity
Terrestrial net primary productivity
Many factors influence primary productivity rates, but the most important on land are temperature and water availability. View image

The nitrogen cycle
The nitrogen cycle
Nitrogen is abundant in the atmosphere but occurs in an inert form that living organisms cannot use directly. In the nitrogen cycle, some of this supply is converted to biologically useful forms. View image

The phosphorus cycle
The phosphorus cycle
Phosphorus is found in water, soil, and sediments. Like nitrogen, it must be converted to biologically useful forms before plants and animals can take it up. View image

Typical forest succession pattern
Typical forest succession pattern
Left undisturbed, an abandoned field will regrow from a meadow into a scrub community, then become populated by pines and ultimately by hardwood trees. View image

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