Background
The authors note that "the longevity and persistence of clonal plant populations are believed to enhance community stability and ecosystem resilience to climate change," citing Steinger et al. (1996), Grabherr and Nagy (2003), and Guisan and Thuiller (2005), while adding that "stability and resilience are thought to be high in arctic and alpine ecosystems, where more than 50% of the plant species are able to reproduce clonally (Korner, 2003)." Thus, "to better understand their ecology, as well as their persistence through past climatic oscillations and their potential resistance to future climate change," de Witte et al. say they "chose to investigate diversity, structure and age in arctic-alpine clonal plant populations."

What was done
The five researchers investigated clonal diversity, as well as the size structure and longevity of genets (a group of genetically identical individuals), in populations of four arctic-alpine plants (Carex curvula, Dryas octopetala, Salix herbacea and Vaccinium uliginosum), in order to evaluate "their persistence under past climatic oscillations." This they did by determining the size and number of genets via an analysis of amplified fragment length polymorphisms and a standardized sampling design in several European arctic-alpine populations, where these species dominate the vegetation, while "genet age was estimated by dividing the size by the annual horizontal size increment from in situ growth measurements."

What was learned
De Witte et al. report that "the oldest genets of D. octopetala, S. herbacea and V. uliginosum were found to be at least 500, 450 and 1400 years old, respectively," but they say that "the largest C. curvula genet had an estimated minimum age of c. 4100 years and a maximum age of c. 5000 years, although 84.8% of the genets in this species were <200 years old."

What it means
The French and Swiss scientists say their results indicate that "individuals in the studied populations have survived pronounced climatic oscillations, including the Little Ice Age and the postindustrial warming," and they note that "the presence of genets in all size classes and the dominance of presumably young individuals suggest repeated recruitment over time," which they say is "a precondition for adaptation to changing environmental conditions." Therefore, they conclude that, acting together, "persistence and continuous genet turnover may ensure maximum ecosystem resilience," noting that their results indicate that "long-lived clonal plants in arctic-alpine ecosystems can persist, despite considerable climatic change," and that they "may indeed show a previously underestimated resilience to changing climatic conditions." In fact, they say their findings suggest that "moderate climate change with an average temperature increase of 1.8°C over the next hundred years and a moderate frequency of extreme climatic events will not lead to local extinctions of long-lived clonal plant populations [italics added]."

References
Grabherr, G. and Nagy, L. 2003. Alpine vegetation dynamics and climate change: a synthesis of long-term studies and observations. In: Nagy, L., Grabherr, G., Korner, C. and Thompson, D.B.A. (Eds.). Alpine Diversity in Europe, Springer-Verlag, New York, New York, USA, pp. 399-409.

Guisan, A. and Thuiller, W. 2005. Predicting species distribution: offering more than simple habitat models. Ecology Letters 8: 993-1009.

Korner, C. 2003. Alpine Plant Life: Functional Plant Ecology of High Mountain Ecosystems. Springer-Verlag, Berlin, Germany.

Steinger, T., Korner, C. and Schmid, B. 1996. Long-term persistence in a changing climate: DNA analysis suggests very old ages of clones of alpine Carex curvula. Oecologia 105: 94-99.