
(Perma)Culture and Sanity
LauraF October 13th, 2010; 12:47:31 PM
Your articles are very helpful. I've heard it repeated that all deserts are man made. Would you know a source for that?
Jack September 6th, 2010; 02:44:51 PM howtosaveseeds.com
Stand back and wait... if you must interfere, plant a fresh acorn an inch or two deep before it has dried, as drying lowers ability to germinate.
Reprinted from (Perma) Culture and Sanity Website
http://tinyorb.net/Jack/
Jack October 13th, 2010; 01:50:32 PM permaculture-and-sanity.com/pcarticles/trees-and-the-water-cycle.php
LauraF,
Many deserts are actually naturally occurring, such as the Chihuahuan and Sonoran deserts in the Southwestern US (formed by rain shadows caused by the Sierra Madres. And deserts do tend naturally to grow along their leeward edges, as dry conditions slowly erode forests.
Humans DO, however, greatly accelerate the growth of deserts, mostly by cutting trees, sometimes by over-burning (to prevent trees from moving into pastureland). Cutting trees or burning over large areas stops the rain cycle, since trees account for the large majority of the fallen rain that returns to the air to make more clouds.
Many areas that began as semi-arid, such as much of the Mediterranean and the Chihuahuan desert in Texas, became desert because of over-cutting or burning of trees (for warships in the Mediterranean, for railroad ties and pasture-burning in the US Southwest). The US Great Plains has been partially desertified by almost complete removal of trees, and will probably become true desert when Human irrigation for agriculture stops.
If you search on the terms 'desertification' and 'salinization' you will find many examples of this from around the world, both past and present. All we as individuals can do is plant trees and work for forest restoration/preservation... as an old saying goes, "The best time to plant a tree is 20 years ago. The second-best time is today."
Thank you for your comment!