Monday, March 15, 2010

The bizarre history of rangeland management research

ResearchBlogging.orgAs with the paper from last Friday, today's paper comes from "Ecological Restoration", one of the few journals that is delivered, in print, to our office. So yeah, I've been reading through it.

This paper is by Sayre (2010; full cite below) and is basically about how the cultural and scientific beliefs of those living in the desert southwest have shaped the way that restoration has occurred there. Southwest refers to southwestern US (Arizona, New Mexico, etc.).

The paper is really a historical essay more than anything else, and so I'm not sure if it really qualifies as 'science'. However, it was really interesting. Basically, Sayre points out that three really big-picture things have dominated the way people have managed this part of the country:
  1. The "Natural" aesthetic laid out by early-20th century writers, specifically John Van Dyke.
  2. The belief that rangeland could be managed for and by livestock grazing (which depended on believing Clements' "climax community" theory).
  3. The unwillingness of (virtually) anyone to look at fire as a management technique.
That's a pretty amazing list. The desert aesthetic laid out by Van Dyke was popularized by his book (Desert), and turned out to be primarily a documentation of a massive drought. So the ideal that so many people believed in was really a landscape already heavily degraded by overgrazing and drought. The climax community theory that Clements promoted, and that was so popular in ecology for the early part of the 20th century, has been shown time and time again to be a poor representation of what is actually happening. And finally, fire has now been shown to be one of the most important factors in maintaining grassland communities.

So people pretty much got that all wrong, which isn't surprising. What is surprising is how long people have clung to those false theories.

The basic idea was that the grasslands would restore themselves if you just 'leave them alone'. What everyone wanted was for the grasslands to be as rich and abundant as they were in 1874. Unfortunately, the southwest grasslands were probably maintained by a more dynamic equilibrium (periodic fire, flood, and drought keeping the native grasses abundant and undesirable species [like mesquite] rare). Even worse, it took these scientists the better part of a century to figure out that all three of those factors above were wrong.

The net effect of all this poor management and questionable science is apparently quite astounding (I haven't visited myself).

"The Nature Conservancy estimates 84% of perennial grasslands in the Apachean Highlands bioregion has been invaded by shrubs; three-fifths of this area is deemed by The Nature Conservancy to be beyond restoration, either because there is insufficient grass to provide the fine fuels needed to carry a fire (which would be necessary to set back shrubs), or because non-native grasses dominate to such an extent that fire, although possible, would not appreciably help the native grasses." (Sayre p 26)

Holy cow.

There's also some discussion in this paper about whether the goal of restoration should be the historical conditions of an area or something else, but that discussion is less fleshed out. I'm under the impression that the author sees no a priori reason to believe historical conditions should necessarily be the ideal.


About a century of poor management in the desert southwest (USA) is directly attributable to the widespread adherence to a series of unfounded beliefs. As a result, large portions of this area are unlikely to ever be restored to 'pristine' or desirable conditions.

Sayre, N. (2010). Climax and "Original Capacity": The Science and Aesthetics of Ecological Restoration in the Southwestern USA Ecological Restoration, 28 (1), 23-31 DOI: 10.3368/er.28.1.23

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