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African Tropical Rainforest: Flexing Its Muscles in Times of Stress
Volume 17, Number 18: 30 April 2014

The African humid tropical biome constitutes the second largest rainforest region of the world; and, unfortunately, deforestation in this Central African region is accelerating, according to Fisher et al. (2013), in ways that are "similar to deforestation patterns in the rest of the tropics." In addition, as the sixteen scientists continue," humid tropical Africa has also borne the brunt of "the 'great drought' that began in the 1960s in the Sahel [and] lasted well into the 1980s, with 20-40% less precipitation in the 30 years following 1960, relative to before," as reported by Hulme (1992), Olsson et al. (2005) and Giannini et al. (2008).

"Compounding this decrease in precipitation," in the words of Fisher et al., "there has been an overall warming trend in Africa at large," as reported by Hulme (1996a,b) and Lewis et al. (2004). And they go on to correctly state that "given less water and hotter temperatures," we may have expected "increasing water stress to decrease CO2 uptake, and move the biome towards a net source of CO2 to the atmosphere," citing in this regard the study of Phillips et al. (2009). However, they say that "paradoxically," both "models and measurements have shown an increase in vegetation productivity and biomass of 0.3-0.4 Pg C/yr in the African humid tropics since the 1960s," citing the studies of Cao et al. (2001), Nemani et al. (2003), Williams et al. (2007), Alo and Wang (2008), Ciais et al. (2009), Lewis et al. (2009), Malhi (2010), and Pan et al. (2011).

So how did it happen? How did what most people thought to be highly improbable - if not impossible - actually occur? Fisher et al. write that "the recent increase in plant productivity has been attributed to the CO2 fertilization effect," citing a wealth of studies that have come to this conclusion, including those of Amthor (1995), Lloyd and Farquhar (1996), Cao et al. (2001), Lewis et al. (2004), Friedlingstein et al. (2006), Stephens et al. (2007), Ciais et al. (2009), Lewis et al. (2009), Malhi (2010), Ballantyne et al. (2012) and Higgins and Scheiter (2012). And in regard to a more recent African study that has yet to appear in print, they write that its authors "found that gross primary production increased over the past 30 years even though soil moisture decreased."

Such is the growth-promoting power of atmospheric CO2 enrichment that many people, who should know better, are doing all in their power to keep from occurring. Clearly, these less-than-objective folks are operating at dangerous cross purposes to what is truly needed to sustain and preserve both nature and mankind's growing numbers.

Sherwood, Keith and Craig Idso

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