A review of subtropical community resistance and resilience to extreme cold spells

Forecasted changes in global climate predict not only shifts in average conditions but also changes in the frequency and intensity of climate extremes. In the subtropics, the passage of extreme cold spells functions as a major structuring force for ecological communities, and can incur substantial losses to biodiversity, agriculture, and infrastructure. If these events persist in the future, it is likely that their effects on subtropical communities and ecosystems will become more pronounced, as tropical species migrate poleward. Recent extreme cold spells in subtropical China (2008) and United States (2010) occurred in ecosystems that are the subject of long-term ecological study, enabling key questions about cold spell affects to be addressed. In this study, we (1) discuss the meteorological drivers that resulted in these two extreme cold spells, and (2) use findings from case studies published in the Ecosphere Special Feature on effects of extreme cold spells on the dynamics of subtropical communities, and on poleward expansion of tropical species and other previously published works to identify consistencies of subtropical community resilience and resistance to extreme cold spells. In this review, we highlight three consistent findings related to this particularly type of extreme climate event: (1) cold spells drive predictable community change in the subtropics by altering ratios of coexisting tropical and temperate species; (2) certain landscape features consistently affect subtropical resistance and resilience to extreme cold spells; and (3) native tropical species are more resistant and resilient to extreme cold spells than tropical nonnative taxa. Our review should improve forecasts of the response of subtropical community dynamics in scenarios where extreme cold spells either increase or decrease in frequency and intensity.