Ken
-----Original Message----- From: owner-lbo-talk at lists.panix.com [mailto:owner-lbo-talk at lists.panix.com]On Behalf Of Lisa & Ian Murray Sent: Friday, March 09, 2001 10:09 PM To: lbo-talk at lists.panix.com Subject: RE: fragile jungle soils
> In a couple of different contexts, I've run into the idea that soil
> reclaimed from rain forests is bad for farming. Jeffrey Sachs makes
the
> idea prominent in some of his recent arguments for why African
economic
> history developed differently over the longue duree. And recently
it
> showed up in an article on Colombia, about how farmers in the
recently
> sprayed Putamayo district would likely be planting coca there again,
even
> if the government made good on its offer to provide $2000 worth of
> fertilizer to each peasant that joined the voluntary eradication
program
> (originally it was supposed to $5000, in cash), because the fragile
jungle
> soils that had no tree cover couldn't support intensive agriculture.
>
> For a bio-ignoramus like myself, it seems puzzling how soil that can
> support the luxuriant growth of a rain forest can't support farming.
But
> maybe it's not a matter of fertility but of proneness to washing
away, or
> of a negative interaction with fertilizer? At any rate, if someone
could
> explain why jungle soil won't sustain intensive farming as well as
> temparate climate soil will, I'd be much obliged. URLS or citations
would
> also be great.
>
> Michael
***************
There's quite a bit of evidence that the canopy drives the nutrient cycling of Amazonian rainforests. The evidence is less clear for African and Asian rainforests. When deforestation occurs, the topsoils are so thin the hot sun bakes the nutrients which are normally protected by the canopy. When the rains come, swooooooosh, they're washed into watersheds. Thomas Lovejoy did a famous study on deforestation as patch disturbances and calculated the minimal size a surviving plot needed to be to prevent collapse; he used methods from island biogeography to guesstimate plot size. Above the South American continent there are rivers of moisture in the sky that are bigger and longer than the rivers on the ground, fractal currents that hold enormous amounts of water. So the worlds longest rivers are in the air. Somewhere on the web there's a site that has a 24 hour video feed of canopy life from multiple camera locations. Somewhere else on the web are "false color" satellite maps of the rivers in the air.
The ecosystem suffering the greatest amount of deforestation is in British Columbia.
<http://studentweb.hunter.cuny.edu/~vcamaran/>
<http://asd-www.larc.nasa.gov/biomass_burn/gbb_toc.html>
<http://cas.bellarmine.edu/tietjen/images/biomass_decline_in_amazonian _for.htm>
For a thorough look at the US' role in tropical deforestation see Richard P Tucker's "Insatiable Appetite" Univ. California Press, 2000.
Ian