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Biodiversity Decline
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- 2. Biodiversity Decline When wesay “biodiversity” we mean species biodiversity. It is measured in the number of species in a given habitat or worldwide.
- 3. Biodiversity Decline Extinctionsare occurring at an exceptionally high rate Human activities are a major cause (Image: “Underestimating the Challenges of Avoiding a Ghastly Future”, in Frontiers in Conservation Science (in en), volume 1, 13 January 2021, DOI:10.3389/FCOSC.2020.615419, ISSN 2673-611X, Wikidata Q105082215)
- 4. Biodiversity Decline Biodiversity Hotspots: a region that is especially rich in biodiversity (i.e. such as 1,500 endemic species of vascular plants) has lost at least 70 percent of their original habitat
- 5. Biodiversity Decline Most ecologistsagree that current rates of extinction are several hundred times greater than historical levels Most studies estimate that extinction rates could rise by 1000 to 10,000 times above past averages in the near future Roughly 50 percent of all natural habitats have been cleared for human use, with 0.5 to 1.5 percent more lost annually Protecting hotspots could prevent this acceleration but only 10 % are currently protected, many only on paper
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- 7. Biodiversity Decline Habitat Fragmentation:when human action divides large sectors of land into fragments with undeveloped parcels that may be too small or isolated to support viable populations habitat loss is believed to be the largest single cause of biodiversity loss worldwide corridors of land that link separate habitat zones is an increasingly popular solution to it (like this one in Brazil)
- 8. Biodiversity Decline Other MajorThreats to Biodiversity Invasive/exotic species Overconsumption & overharvesting by humans Air and water pollution Global climate change
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- 10. “The loss ofbiodiversity is the only truly irreversible global environmental change the Earth faces today” --Dirzo and Raven
Editor's Notes
- #5 A biodiversity hotspot is a biogeographic region that is both a significant reservoir of biodiversity and is threatened with destruction. The term biodiversity hotspot specifically refers to 25 biologically rich areas around the world that have lost at least 70 percent of their original habitat. The remaining natural habitat in these biodiversity hotspots amounts to just 1.4 percent of the land surface of the planet, yet supports nearly 60 percent of the world's plant, bird, mammal, reptile, and amphibian species. From: https://www.sciencedaily.com/terms/biodiversity_hotspot.htm Vascular plants, also known as tracheophytes, form a large group of plants that are defined as those land plants that have lignified tissues for conducting water and minerals throughout the plant. They also have a specialized non-lignified tissue to conduct products of photosynthesis. Wikipedia
- #6 To date, about 50 percent of the planet's natural habitats have been cleared for human use, and another 0.5 to 1.5 percent of nature is lost each year.
- #9 Image shows Cortaderia jubata, a species of grass known by several common names, including purple pampas grass and Andean pampas grass (https://en.wikipedia.org/wiki/Cortaderia_jubata). Local species are not adapted to compete with them nor do they face natural predators.
- #10 From a practical point of view, humans derive many kinds of food, medicine, and fuel from plant and animal sources. Healthy ecosystems also provide many other important services to human communities. These functions are so basic that they can go unnoticed, until they disappear. The American Dust Bowl occurred in the 1930s because repeated plowing and cultivation across the Great Plains broke up the cover of prairie grasses (viewed as weeds by farmers) that held the soil in place. By spending $1.4 billion on land acquisition and related measures to reduce pollution in the target areas, New York avoided building a $6–8 billion filtration plant to purify water from these sources Many advocates also make aesthetic and moral arguments for conserving biodiversity. Species richness adds to our enjoyment of nature, even at a simple level: most hikers would probably agree that a wild meadow, with its variety of plants, animals, and birds, is more interesting to visit than a cultivated field. At their desks, students pick one of these and reflect on it—what is your experience with this system like? Specific memories or situations? Breakdowns of the process? It’s relationship with other systems?
- #11 Video link is to a NASA video: Sting of Climate Change (https://climate.nasa.gov/climate_resources/41/video-sting-of-climate-change/) In the words of biologists Rodolfo Dirzo and Peter Raven, "The loss of biodiversity is the only truly irreversible global environmental change the Earth faces today"