How extinction of five-tonne sloths slows up growth along the Amazon

[dipsydoodle]

Vast regions of the Amazon are growing more slowly than they were several thousand years ago because they lack the fertilising effect provided by South America’s distinctive “mega-fauna” – the very large mammals that went extinct soon after the arrival of humans.

A study of how soil nutrients are distributed within the Amazon basin has revealed there is a dearth of vital minerals such as phosphorus because large mammals no longer roam the region to fertilise the soil with their dung.

Scientists believe that the extinction of large herbivores, such as five-tonne ground sloths and armadillo-like glyptodonts the size of small cars, led to a serious imbalance of soil minerals which is still having an impact today.

“It is having a big effect. The Eastern Amazon in particular is phosphorus-limited which means that if you added phosphorus to the region the trees there would grow faster,” said Christopher Doughty of the University of Oxford, the lead author of the study.

http://www.independent.co.uk/news/science/how-extinction-of-fivetonne-sloths-slows-up-growth-along-the-amazon-8756432.html

[Tien1985]

1. This is really fascinating

I was drawn in by the headline--it's hard to even imagine a 5 ton sloth.

[dipsydoodle]

3. They were the height of a mammoth

and as stocky as a rhino.

[Scootaloo]

2. Their extinction has also been suggested as a factor in the Mojave and Everglades

For instance, the Joshua trees of the Mojave have these big giant clusters of fleshy fruit chock full of hard seeds. Thing is? Nothing eats the fruits. When the fruits finally dry and fall off, the seeds stay more or less right there, and are quickly eaten by seed-eating animals like mice and ants. Since the soil in the Mojave is piss-poor, any seeds that aren't eaten and manage to germinate ill be in competition with an established adult plant (the parent plant) and will probably die early on.

Something ate that fruit in the not-too-distant past. It's edible to humans, but we're a rather new arrival (at least, new as far as flora of the Mojave is considered). Something ate these things by the bushel, and dispersed the seeds far and wide in convenient piles of fertilizer. In fact, these tertiary-era turds have been found! ...they belong to the giant ground sloth.

For more information, reference this post by Pharyngula co-blogger, Chris Clarke, where he makes a case that, if we ever do start re-generating extinct species, we should go with ecological function over charismatic value - starting with Nothrotheriops;
http://freethoughtblogs.com/pharyngula/2013/03/10/bring-back-the-shasta-ground-sloth/

[happyslug]

4. There are persistent rumors that the Ground Sloth is NOT extinct.

The reports are all from South America:

http://markgelbart.wordpress.com/2011/03/30/does-a-species-of-giant-ground-sloth-still-exist-in-the-amazon-rain-forest/

http://www.academia.edu/683586/Does_the_ground_sloth_Mylodon_darwinii_still_survive_in_South_America

http://en.wikipedia.org/wiki/Mapinguari

These reports are questionable, but it is possible for a sub-species to survive in the Amazon.