Sunday, May 19, 2013

What about the forests?

In his TED talk, Allan Savory proposes increasing livestock stocking rates as a means to replenish degraded lands (Savory, 2013). While Savory claims that increased livestock contributes to a more productive grassland, he seems to be completely oblivious to their effects on forest regeneration. While large tracts of the world's land are covered in grasslands, this wasn't always the case. Vasts swaths of North America, the majority of Europe, and even countries not typically associated with forests such as Iraq and Jordan were covered in ancient forests. Pressure from agrarian and pastoral societies converted these ancient forests into the modern grasslands (or in the case of Iraq, deserts) seen today. Where the most fragile of these forests (such as the low moisture forests of Iraq) quickly deteriorated into myth, in modern times even the most robust tropical forests are under threat to conversion to grassland (Food and Agriculture, 2012) . Furthermore, the browsing of livestock significantly slows forest regeneration (or even stops it) as livestock destroy and damage young saplings (Zamora et al., 2001)(in his talk, Savory commented on a landscape being invaded by woody plants as a negative and showed a landscape lush with grass but containing trees damaged by elephants as a positive(Savory, 2013)).

Willamette Valley image from Google Earth
The included photo of the Willamette Valley shows a local example of human made grasslands (the whitish areas are dry agriculture fields photographed in summer when google earth's satellites aren't blocked by the winter's cloud cover - also note the extensive "dead" areas that are the urban environments of Portland, Salem, and Eugene/Springfield). The Willamette Valley is a unique natural experiment in that it was originally maintained by Native American fire regimes, was abandoned by natives (through displacement and disease), quickly reforested, and then was re-managed by white settlers into its current state (Tracing the History, 2012). Surely, the green forested regions of the mountains hold more moisture than the dry, agricultural regions or dead urban spaces?  Increasing livestock stocking rates, decreasing forest regeneration, and increasing human management  is what has converted the Willamette Valley into what it is today. Savory's recommendations would be further detrimental to water storage (in the green forest), biodiversity (agricultural lands or fields compared to forest lands), and carbon sequestration (carbon held in annual plants that cycles quickly or held in long lived trees that cycles slowly) even in an environment as water rich as the northwest.

Tracing the History of Fire in the Willamette Valley. (2010, March). Fire Science Brief.

Food and Agriculture Organization of the United Nations. (2012). State of the World's Forests. Rome.

Savory, Allan. “How to fight desertification and reverse climate change.” 2013.

Zamora, R., Gomez, J. M., Hodar, J. A., Castro, J., & Garcia, D. (2001). Effect of browsing by ungulates on sapling growth of Scots pine in a Mediterranean environment: consequences for forest regeneration. Forest Ecology and Management.

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