THE EARTH IS A LIVING PLANET – IT BREATHES 405.34 Aug 7, 2017 Changes in the Composition of the Atmosphere

The Earth is the way it is because of the living things on it…

Earth History 4.5 million to present (1/1000th of earth history) 2.3-2.0 bya: Oxygen 1.8 bya: first eukaryote 0.9 bya: first animals 0.5 bya: Cambrian 0.24 bya:Mesozoic 0.065 bya:Cenozoic 4.5 bya: Earth Forms 4.0 bya: Oldest Rocks 3.4 bya: Oldest Fossils

The Effects of Life over Earth’s History: 2.2 bya How do we know that oxygen wasn’t always present in the Earth’s atmosphere? Maybe Earth is just different from Venus and Mars… Banded iron formations are first seen 2.5 billion years ago, showing that oxygen must have been present in the ocean to precipitate iron out of solution as iron oxides in sedimentary strata. There absence in older strata means that oxygen was not present in appreciable amounts.

The Effects of Life over Earth’s History: 350 mya Terrestrial plants were radiating, sucking up CO2 and producing O2. Huge expanses of swamp forests dominated the equatorial zone. Photosynthetic rates were high, but the trees were preserved under sediments when they died and fell…. Creating our coal deposits. Photosynthesis produced lots of O2, but with less decay, it stayed in the air instead of being breathed in and used by decomposing bacteria.

The Effects of Life over Earth’s History: 350 mya The Carboniferous “Pulse”

The Effects of Life over Earth’s History: 65 mya

The K-T Extinction affected atmospheric oxygen levels as plants went extinct and terrestrial photosynthetic activity declined.

Thousands of Genera Millions of Years Ago All genera “well described” genera The “big five” Mass Extinction Events Thousands of Genera Millions of Years Ago http://en.wikipedia.org/wiki/File:Phanerozoic_biodiversity_blank_01.png

The Effects of Life over Earth’s History: now https://petermaas.nl/extinct/

BIODIVERSITY NOW http://www.coral.org/node/3230

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Millenium Ecosystem Assessment (2006) http://englishontour.blogspot.com/2011/03/beetles.html

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Insect Diversity

http://web.pdx.edu/~stul/images/insectdiversitysmall.gif

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Herbivores, Predators, Detritivores, Pollinators http://ambergriscaye.com/critters/redeyedtreefrog.html http://australian-animals.net/plat.htm http://freakz.info/2011/09/21/10-interesting-seahorse-facts/ http://www.pbase.com/image/37557333 http://www.bbc.co.uk/nature/life/Blue_Whale Herbivores, Predators, Detritivores, Pollinators http://www.hodag.info/what%E2%80%99s-going-on-here-then-100

Most vertebrate species are fishes http://www.elp.manchester.ac.uk/pub_projects/2003/MNZO0MLK/lecture1.htm

But do we NEED all these species??

There’s a lot of redundancy in nature… http://katherinegerdes.com/portfolio/11/rainy-day-jewels

Are all species equally important? If not, which ones are critical?

with without

What does biodiversity do??