Print PagePolar Regions are expected to experience dramatic effects from global climate change. How ecosystems in the Arctic and Antarctic are affected does not always coincide. The magnitude of climate change effects may be uncertain, but the cascading processes that occur in polar ecosystems are very similar. Increased soil temperature hastens organic matter decomposition and nitrogen (N) turnover, thereby potentially changing plant community composition. We integrated and compared the data and approaches from three comparable published studies in the Arctic and Antarctic to examine effects of climate change on soil N and plant ecosystem responses. The published data from two separate arctic studies were made available for this purpose. Both examined bioavailable soil N, measured with Plant Root Simulator (PRS™)-Probes, and plant community composition. One study focused on the effects of N addition (4g N m-2yr-1) and warming damage of Empetrum hermaphroditum, while the other focused on the effects of N addition to nonsorted circles. The third study, in Antarctica and the Atlantic sector of the Southern Ocean, examined experimental warming (<1˚C) effects on conventionally measured soil N and organic matter decomposition at three locations: Anchorage Island, 67˚S; Signy Island 61˚S; and Falkland Islands, 52˚S.
Results/Conclusions
Nitrogen addition to E. hermaphroditum and nonsorted circles significantly increased bioavailable soil N (P<0.0001), as measured by the PRS™-probes. Soil N supply was not increased by simulated warming damage of E. hermaphroditum. Plant community response to nitrogen addition was an increase in E. hermaphroditum, but no significant change of plant biomass in nonsorted circles. However, graminoid biomass significantly increased in the vegetated rims of fertilized nonsorted circles. In Antarctica, organic matter breakdown, measured by soil respiration rate, was significantly increased by warming at Signy Island and the Falkland Islands. However, soil N extractions showed no difference. Counter-intuitively, soil respiration rate was greatest at the coldest study site (Anchorage Island), where soil extractable N was highest. This result suggests that respiration may be more controlled by soil N than soil warming. Polar studies such as these indicate that substantial warming is required to elicit significant effects, but if climate change becomes more extreme, factors such as soil N supply will likely be altered. Studies such as these discussed are crucial in helping to quantify and adapt to the effects of climate change in Polar Regions. Plant Root Simulator (PRS™)-probes can be an effective tool for assessing changes, as a results of climate change, in bioavailable soil nutrients.
