Conventional Wisdom May Worsen Savannah Droughts
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From Texas to South Africa, farmers and ranchers on the drought-plagued savannah know that cutting down water-hungry shrubs and trees helps keep more moisture in the soil. This conventional wisdom has ruled land management for generations but there is one problem—it may not be true.
According to new findings by researchers at Texas A&M; University in College Station, the exact opposite might be the case.Bradford Wilcox and colleague Yun Huang, hydrologists at the university, looked at the water levels of four of the major rivers in Texas—using data going back to 1925. Wilcox explained:
Rivers on the Edwards Plateau not only are not disappearing, but they are increasing in flow...by a lot. I mean, it's doubled. That's really big.
A hundred years ago, the Edwards Plateau had been severely degraded by overgrazing. As the state developed, livestock were removed and the area was given a chance to recover. Woody shrubs eventually moved in and, since this has happened, there has been an increase in water flow that Wilcox says must be related to the returned plants.
I can't really think of any other plausible explanation...the obvious no-brainer is that it has had this massive change in land cover. There's more vegetation, there's more cover, there's more protection. And so it allows more water to enter into the soil.
He was quick to say, however, that his research is so far limited to the karst savannahs of western Texas. The permeable soil of the region, he explained, may behave differently than that of other savannahs.
Land managers around the world call for the removal of woody shrubs from drought-stricken land. Even in Texas, ranchers seek help from the government to rid their property of the vilified water hoards. There are still a lot of gaps in the research, but this new finding suggests that these management plans need to be reevaluated.