Drought-Prone Rangelands in a Warming World
Shafran-Nathan, R., Svoray, T. and Perevolotsky, A. 2013. Continuous droughts' effect on herbaceous vegetation cover and productivity in rangelands: results from close-range photography and spatial analysis. International Journal of Remote Sensing: 10.1080/01431161.2013.793864.
The three Israeli researchers report that the droughts "led to spatial convergence of the productive patch size," and that both "productive and less productive patches persisted while plant cover decreased with rainfall reduction." And "interestingly," as they put it, "production processes continued long after the last rainfall event ... for 45 days in 2007-2008 and for 66 days in 2008-2009, unlike two and a half weeks in regular years." In addition, they say that "even though there was almost no rainfall supplementation during the productive phase in either year, plant cover increased until the peak of the productive phase and then declined until senescence."
Another strategy that they felt was operative in maintaining rangeland productivity in drought-stressed years was the development of "a relatively stable seed bank that is accumulated over the years and may buffer the effect of drought," citing in this regard the work of Osem et al. (2004). Most important of all, they concluded that the various phenomena they documented made the ecosystems they studied "more resilient than expected," leading them to declare that rangelands may well "maintain productivity under more severe drought scenarios than those currently predicted in the climate change literature." And, it might be added, these ecosystems appear to be capable of doing so right now, even without the additional future help that will be provided by the aerial fertilization effect and the transpiration-reducing effect of the additional CO2 that will be released to the air in the years and decades to come via mankind's continued burning of coal, gas and oil, which should make things better still for Earth's rangelands for a long, long time to come.
Grime, J.P., Fridley, J.D., Askew, A.P., Thompson, K., Hodgson, J.G. and Bennett, C.R. 2008. Long-term resistance to simulated climate change in an infertile grassland. Proceedings of the National Academy of Sciences 105: 10,028-10,032.
Osem, Y., Perevolotsky, A. and Kigel, J. 2004. Site productivity and plant size explain the response of annual species to grazing exclusion in a Mediterranean semi-arid rangeland. Journal of Ecology 92: 297-309.
Yosef, Y., Saarfoni, H. and Alpert, P. 2009. Trends in daily rainfall intensity over Israel 1950/1-2003/4. Open Atmospheric Science Journal 3: 196-203.