A recent HN comment implied that camel herding was a significant factor in aridification of North Africa and the Middle East. The context and tone made me wonder if the comment simply reflected anti-nomad (i.e. anti-Bedouin, anti-Berber) prejudice, but there could just as well be something to it. I'm trying to avoid rabbit holes so I put it out of mind.
The comment seems incorrect. Herds are good for the soil. They flatten grasses keeping moisture in, allowing for more growth. In the past, people believed the opposite - and this is perhaps still believed in parts of the world.
Managed properly, yes. The soils of the Midwestern US were formed largely by herds of migratory bison for instance.
The problem comes in when you don't defer grazing or give things a chance to regrow (see video in sib comment below). That absolutely can lead to desertification.
As populations increase and nomadism becomes nonviable (so ground is not given a rest from grazing) it appears that's what happens.
> The comment seems incorrect. Herds are good for the soil. They flatten grasses keeping moisture in, allowing for more growth. In the past, people believed the opposite - and this is perhaps still believed in parts of the world.
For some reason, the idea of complex organisms (in this case: mammals) migrating to new lands and fertilizing it seems counter-intuitive to me, but it does make sense in some way. I would've assumed that more simple organisms took this land long before mammals emerged.
The biggest gripe I'd have with it would be: why would they move into those lands? There's nothing there for them. But the idea of them slowly extending fertilized soil does seem intriguing.
It appears sort of counter-factual to me that we, who are (presumably) even more complex, seem to reverse this process. There seems to be a sweet-spot in evolution of a species to benefit the land on which they live on (and that around it), and we seem to be past it.
Goats are also a harbinger. They can and will eat any last remaining plant matter in an area, tipping it fully over to desert.
It’s often overstated as goats being destroyers. They aren’t or don’t have to be. The goats are the agent of destruction, but the herders are the actual destroyers.
For the restoration of the loess plateau in China, they mandated that goats had to be corralled instead of ranged, to allow the restoration to get a foothold instead of ending up as the most expensive goat meat ever.
I've never seen ground that naked, not a spec of green except for trees. (and this coming from someone who lives in a very arid region of the SouthWestern US). Even very arid land (in Nevada or Arizona for instance) has significant vegetation so I wondered what was going on.
Part of the way through the video (6:09) it becomes apparent (to me anyway). Goats and sheep. Somewhere in there they are actually beating tree leaves down for the critters to eat because there is simply nothing else.
That's a fascinatingly stark landscape. I've visited rural communities in Mexico (semi-arid), Ecuador (highland grass lands), and SE Asia (jungle) that have that same remote village vibe, and the lifestyle similarity makes the contrast with the landscape all the more fascinating. I've also visited the Gobi desert (at least, the edge of the Gobi, where the mile-high sand dunes meet the endless grass lands) and that landscape in Iran somehow seems so much more desolate.
[1] Maybe the author wasn't using the terminology correctly, or the terminology shifted or was refined subsequently, but in the article, "A precarious balance upset", from the 1977 publication the author suggests that desertification can at least in principle lead to aridification as stripping the land of vegetation dries out the soil, which can ultimately effect precipitation patterns. EDIT: Okay, I think I get it now. It's the reverse: aridification can lead to long-term desertification, while there other processes that can establish long-term desertification, notwithstanding the end result is also aridity.
A similar thing happened in south Texas - the land that Big Bend state park now occupies was grassland in the 1880s but because it featured low rainfall, was quickly overgrazed. The owners ended up giving the land to the state because it had been turned into worthless desert, coincidentally in 1935. Now 85 years later it still hasn't recovered to grassland but has beautiful desert vegetation. It is simultaneously beautiful and horrible.
I don't think it's the goats! I think it's the salinity found in parts of the Zagros mountains and this video was probably recorded in the Lake Urmia watershed. Pistachios are especially salt tolerant so they're the only plants that can grow there, despite the marine deposits.
