More EcosystemsRed Spruce – Fraser Fir Forest in the Appalachian Mountains of North Carolina

Grassland on rolling hills in North Dakota

Mid-montane conifer forest, Yosemite National Park, CA, about 2,000 m in elevation.

BiomesBiomes are groupings of similar ecosystems or landscapes. Biomes are at a much larger scale.

Our text uses “Major Vegetation Types of North America.” These terms are used for biomes as well.

Ecological SuccessionEcosystems are dynamic systems always changing. This section

deals with the changing of vegetation communities or ecosystems through time.

Ecological Succession

- Biotic communities giving way to other biotic communities.

- The Ecosystem is changing during succession.

- Changing conditions pave the way for other species.

- Pioneer species start Ecological Succession.

Note: Humans can put back succession and manage for certain successional stages.

- Climax Ecosystem – The last stage in ecological succession. This is an ecosystem in which populations of all organisms are in balance with each other and with all existing abiotic factors. A climax ecosystem can change sometimes if climate changes or the introduction of introduced species.

Bare Rock

Moss

Weeds

Annual Grasses

Perennial Grasses

Shrubs

Coniferous Trees (Pines)

Hardwood Trees (Oak-Hickory)

Hardwood Trees (Beech-Maple)

Primary Succession – Occurs when an area has not been previously occupied. This starts with bare rock. Examples: Bare rock exposed by retreating glaciers, earthquakes, landslides, and volcanic eruptions.

Primary Succession on Bare Rock. (Moss invades bare rock and acts as a collector, accumulating a layer of

soil sufficient for additional plants to become established.)

Bare rock gives way to moss. Moss gives way to weeds. Weeds give way to annual grass, etc. The ecosystem is changing.

Secondary Succession – Starts with preexisting soil. This is when a biotic community is reinvading or an ecosystem succession is set back. Examples: Abandoned agriculture fields slowly succeed to deciduous forests.

Secondary Succession

Grass grows fast and is a good invader but is easily shaded out by other vegetation. Other vegetation changes the conditions and the conditions are no longer beneficial for grass.

Abandoned Field

Annual Grasses

Perennial Grasses

Shrubs

Coniferous Trees (Pines)

Hardwood Trees (Oak-Hickory)

Hardwood Trees (Beech-Maple)

Introduced SpeciesIntroduced or Exotic Species are species from foreign

ecosystems. They are brought to new ecosystems by people accidentally or on purpose.

Introduced or Exotic is the opposite of native. A native species is originally found in the ecosystem of interest.

Introduced species cost the USA 138 billion dollars a year.A Few Exotic Plants Found in North America:

Tree-of- Heaven, Kudzu, Chinese ChestnutIntroduced species can be problematic because they have

no natural predators or parasites in the newly invaded ecosystem. When introduced or exotic species numbers greatly increase, they are termed invasive or invasive exotics. Invasive exotics can greatly degrade ecosystems.

How do you control invasive exotic plants? Encourage herbivores (if possible and those herbivore are native), herbicides, physical control such as cutting and pulling.

American Chestnut

- The American Chestnut is native to Eastern North America.- The Chinese Chestnut originally from China and was brought to Eastern North America in the early 1900s. The Chinese Chestnut carried a disease (a fungal blight) which decimated the American chestnut population.

Chinese Chestnut

Historic Range of American Chestnut

By 1950, the fungal blight killed nearly every living American chestnut tree. However, there is hope of bringing the American Chestnut back by using biotechnology techniques.

American Chestnut

Conservation BiologyConservation Biology is a relatively new science that

studies the impact of human societies on the nonhuman landscape. Conservation biology is interested in conserving genetic diversity, species diversity and ecosystem diversity.

When studying conservation biology, endangered species, minimum populations, human sustainable development, land management and ecosystem restoration, are important topics.

Ecosystem Restoration – the process of modifying the environment and the vegetation of an ecosystem that has been degraded by human-caused disturbances. Ecosystem restoration strives to return that degraded ecosystem to its pre-disturbed state.

Paired photographs taken before and after 64 years of fire-suppression management near Ebbetts Pass in the Sierra

Nevada of California.

Thinning, followed by prescribed fire, has restored a similar forest back to a condition that resembles the natural vegetation.

1929 1993 Today

Ecosystem Restoration in Action

BIO 141 Botany with Laboratory

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