Evaluation of climate warming effects on tundra plant composition

Background/Question/Methods

Arctic regions are warming at unprecedented rates.  Both experimental and observational data indicate such changes have and will continue to alter the growth form composition of tundra plant communities.  However, much less is known about the consequences for individual species, despite widespread concern that climate warming could lead to substantial loss of tundra species. We used decadal scale monitoring data from 87 sites in alpine, subarctic and Arctic tundra sites throughout North America and Europe together with 31 warming experiments in the same region to address the hypothesis that warming decreases the relative abundance of cold-tolerant species and increases the relevant abundance of warm-tolerant species (thermophilization).

Results/Conclusions

Climate warming was evident over the monitoring period.  Community composition under ambient conditions tracked changes summer temperatures, with increased dominance of warm-tolerant species as study sites warmed.  However, the rate of species turnover with in situ warming was far lower than that over latitudinal and elevational gradients in summer temperature, indicating substantial temporal lags in community turnover with climate change.   Experimental warming effects on composition were weaker than those seen in the monitoring data, although trends suggest that long-term experimental warming also induces plant community thermophilization.