The Biosphere and You. Human impact on ecological systems

Transcription

1 The Biosphere and You Human impact on ecological systems

2 Do ecosystems change over time? What could cause those changes?

3 What can cause catastrophic disturbances in ecosystems? Anthropogenic Cause Nuclear contamination Deforestation Over harvesting Natural Cause Volcanic Eruptions Wild Fires Drought Hurricanes

4 Ecological succession in terrestrial and marine ecosystems results from both human-caused (anthropogenic) disturbances, and natural disturbances. Mt. Saint Helens Back From the Dead - NOVA Ashes to ashes

5 How Nature Repairs itself succession

6 SUCCESsion the key to starting over Ecological succession is a force of nature. Ecosystems are in a constant process of change and restructuring. Hank on Succession

7 Impact of a species on its own environment. Sudden change in the conditions of the environment

8 Natural communities change constantly. Succession is a change in the structure and makeup of the living parts of a community over time. Original community catalyst time Wind Fire Lightening Drought Human impact Climax community succession

9 A Natural Example Mount Saint Helens

10 Succession may be initiated either by formation of new, unoccupied habitat (e.g., a lava flow or a severe landslide) or by some form of disturbance (e.g. fire, severe wind, logging) of an existing community.

11 Primary succession when the conditions of an environment suddenly and drastically change.

12 Primary succession - occurs on an area of newly exposed rock or sand or lava or any area that has not been occupied previously by a living (biotic) community. Start from scratch animation

13 Pioneering species

14 builds humus

15 Secondary succession Succession when the conditions of an environment change less dramatically. Something living still exists on the site.

16 animation Secondary succession - takes place where a community has been removed, e.g., in a plowed field or a clear cut forest but some remnants of a community remains (not starting from scratch )

17 Does ecological succession ever stop? There is a concept in ecological succession called the "climax" community. The climax community represents a stable end product of the successional sequence. In the climate and landscape region of the Olympic National forest ecosystem, for example, this climax community is the Coniferous Forest" subdivision of the Boreal Biome.

18 Ecosystem biodiversity How does succession contribute to healthy ecosystems and biodiversity?

19 the variety of different types of life found on the Earth and the variations within species. It is a measure of the variety of organisms present in different ecosystems. This can refer to genetic variation, ecosystem variation, or species variation (number of species) within an area, biome, or the planet.

20 The richness of biodiversity depends on the climatic conditions and area of the region. Biodiversity is not distributed evenly on Earth. It is richest in the tropics. Terrestrial biodiversity tends to be greater near the equator, which seems to be the result of the warm climate and high primary productivity. Marine biodiversity tends to be highest along coasts in the Western Pacific, where sea surface temperature is highest and in the mid-latitudinal band in all oceans.

21 Why is biodiversity important? It is a direct indication of the health of the ecosystem greater diversity = stronger ecosystem (less susceptible to catastrophic /extinction events

22 Since life began on Earth, five major mass extinctions and several minor events have led to large and sudden drops in biodiversity. The Phanerozoic eon marked a rapid growth in biodiversity via the Cambrian explosion a period during which the majority of multicellular phyla first appeared.

23 marine example The coral reef

24 Ted Talk What s the baseline? What types of disturbances might occur in a marine ecosystem?

25 a baseline is a point of reference against which significant change can be measured. Why is it important to have an accurate baseline for a marine (or any) ecosystem? shifting baselines our point of reference about what is natural in an ecosystem shifts until we accept its current state as normal, and therefore, lower our standards about its health and sustainability.

26 Great Barrier reef Scripps Institute: Paradise Redefined part 1 Paradise Redefined part 2 Do you think coral reefs can recover from natural disturbances at the same time that anthropogenic disturbances are increasing? Why or why not?

27 Great Barrier Reef video

28 Humans in the Biosphere hank Hank s take on human impact

29 Tragedy of the Commons simulation Do you think people treat common resources differently than privately owned resources?

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