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Desert Plants in a Warming World of More Variable Precipitation
Reference
Salguero-Gomez, R., Siewert, W., Casper, B.B. and Tielborger, K. 2012. A demographic approach to study effects of climate change in desert plants. Philosophical Transactions of the royal Society B 367: 3100-3114.

Background
In considering what to expect in a CO2-enriched and warming world of more variable precipitation, the authors write that "a far-too-often overlooked fact is that desert flora have evolved a set of unique structures and mechanisms to withstand extensive periods of drought," among which are "succulence (Smith et al., 1997), deep roots (Canadell et al., 1996), modified metabolic pathways (Dodd et al., 2002), high modularity (Schenk et al., 2008) and bet hedging mechanisms such as seed dormancy (Angert et al., 2010) or extreme longevity (Bowers et al., 1995)," further noting that "these structures and mechanisms are thought to enable plants to buffer the enormous variability found in deserts," so that "owing to such adaptations, projected changes in abiotic conditions may still fall within the range of variation that desert plants are accustomed to without large consequences for long-term population viability."

What was done
To further explore this potentiality, Salguero-Gomez et al., as they describe it, "provide an overview of how variable precipitation affects perennial and annual desert plants," after which they "implement an innovative, mechanistic approach to examine the effects of precipitation on populations of two desert plant species," which approach "couples robust climatic projections, including variable precipitation, with stochastic, stage-structured models constructed from long-term demographic data sets of the short-lived Cryptantha flava in the Colorado Plateau Desert (USA) and the annual Carrichtera annua in the Negev Desert (Israel)."

What was learned
The four researchers say they found "a surprising pattern of increased population growth for both study species when [they] compared population dynamics in the future to current conditions, consistent with increasing precipitation in Utah, USA, and despite decreasing precipitation in Israel." And they thus state that their findings (1) demonstrate C. flava's improved demographic performance in wetter years and (2) highlight the potential of the annual C. annua to buffer the stochasticity of drier years via its seed bank.

What it means
Salguero-Gomez et al. say their study "contributes two notable exceptions to the accepted view that short-lived species, regardless of habitat, are particularly vulnerable to climate change," emphasizing that their findings "challenge the commonly held perception based on correlative approaches (e.g. bioclimatic envelope approaches) suggesting that desert organisms may be particularly vulnerable to climate change."

References
Angert, A.L., Horst, J.L., Huxman, T.E. and Venable, D.L. 2010. Phenotypic plasticity and precipitation response in Sonoran desert winter annuals. American Journal of Botany 97: 405-411.

Bowers, J.E., Webb, R.H. and Rondeau, R.J. 1995. Longevity, recruitment and mortality of desert plants in Grand Canyon, Arizona, USA. Journal of Vegetation Science 6: 551-564.

Canadell, J., Jackson, R.B., Ehleringer, J.R., Mooney, H.A., Sala, O.E. and Schulze, E.D. 1996. Maximum rooting depth of vegetation types at the global scale. Oecologia 108: 583-595.

Dodd, A.N., Borland, A.M., Haslam, R.P., Griffiths, H. and Maxwell, K. 2002. Crassulacean acid metabolism: plastic, fantastic. Journal of Experimental Botany 53: 569-580.

Schenk, H.J., Espino, S., Goedhart, C.M., Nordenstahl, M., Cabrera, H.I.M. and Jones, C.S. 2008. Hydraulic integration and shrub growth form linked across continental aridity gradients. Proceedings of the National Academy of Sciences USA 105: 11,248-11,253.

Smith, W.K., Monson, R.K and Anderson, J.E. 1997. Physiological Ecology of North American Desert Plants. Springer. New York, New York, USA.

Reviewed 27 March 2013