Content sample (ENVR 100 p. 1/3)
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Biodiversity:
- is not evenly distributed on earth (and is richest near the equator)
- is critical for our well-being and survival
- increases resilience
- is declining fast.
Let's look at each of these in detail, starting with the first two together.
Unevenness and Criticality
In fact, biodiversity is richest at the equator (see image above left). This concept is called the latitudinal species gradient Links to an external site.. This is likely due to more water and sunlight energy being available at the equator, as well as climate stability over geological time in this region. The gradient in biodiversity occurs north to south of the equator in freshwater, terrestrial, and marine systems. In marine systems, the pattern is present irrespective of the ocean structure, from the deepest depths to shallow coral reefs. The pattern occurs independently across different continents and oceans. In animals and plants, oceans and land, biodiversity is richest near the equator.
Global biodiversity is highly concentrated in a few patches on earth, called biodiversity hotspots. The image below shows vascular plant species diversity, as the number of vascular plant species per 10,000 km 2.
Explore the hotspots ON this hotspot map!
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In a world where conservation budgets are insufficient, given the number of species threatened with extinction, identifying conservation priorities is crucial. British ecologist Norman Myers defined the biodiversity hotspot concept in 1988 to address the dilemma that conservationists face: what areas are the most immediately important for conserving biodiversity? The biodiversity hotspots hold especially high numbers of endemic species, yet their combined area of remaining habitat covers only 2.3 percent of the Earth's land surface. Each hotspot faces extreme threats and has already lost at least 70 percent of its original natural vegetation. Over 50 percent of the world’s plant species and 42 percent of all terrestrial vertebrate species are endemic to the 35 biodiversity hotspots.
This image below shows the 35 biodiversity hotspots in the world. Take a look at our West Coast.
Principle 2: Biodiversity is critical to our well-being and survival
One way to think of this is in terms of ecosystem goods and services.
Human systems are embedded in ecosystems and we rely on them for all of our raw materials such as wood, cotton, water, fish, crops, and wildlife.
These are ecosystem goods—tangible, quantifiable items.
Ecosystem services are the conditions and processes through which natural ecosystems and the species that make them up sustain and fulfill human life. Some authors talk about these as two different things (ecosystem goods and ecosystem services), as I have here.
Many other authors, like Donella Meadows, talk about ecosystem services as an all-inclusive that includes ecosystem goods. The point here is that we cannot live without our ecosystems, and our ecosystems are deeply dependent on biodiversity to maintain their functioning.
Again, ecosystem services are the conditions and processes through which natural ecosystems, and the species that make them up, sustain and fulfill human life.
What vital ecosystem service is happening in the image below?
Yet bees are declining in the U.S. and around the world due to a syndrome called “colony collapse disorder."
Pollination is an ecosystem service. One response to the bee declines is research on creating little pollinating drones. This is actually in development, but remember what Meadows says about this and think about all the cost, waste, and energy necessary to do this job that the bees do for free. Plus, bees make honey!!
Think about the ecosystem services of a single tree. It photosynthesizes, taking in carbon dioxide and sunlight and creating food, oxygen, and wood for us. It stores carbon. It makes shade. It makes habitat for other organisms, etc, etc, etc!
Next, we will look at the other two principles: Resilience and Decline.
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