Newfound strains of Janthinobacterium 

 from soil in Alaska's boreal forest form 

 nondescript colonies at warm tempera- 

 tures (above), but start to produce red 

 and purple pigments, along with antibi- 

 otics, at cold temperatures (below right) 



ilar to our eyes, one of them 

 turns out to be a hotbed of a 

 particular kind of antibiotic- 

 producing bacteria (Janthi- 

 nobacterium). They've become 

 a laboratory favorite because of 

 the bloody crimson and inky 

 purple pigments they produce — 

 but only at cool temperatures \scc 

 photographs on this page]. Whatever the 

 function of the pigments turns out to be, 

 it seems likely that the 

 Alaskan bacteria have devel- 

 oped storage compounds, 

 communication signals, and 

 other specialized biochemi- 

 cals adapted to their high- 

 latitude life. 



The emphasis of the microbial observatories is on 

 understanding microbial diversity, but they are also 

 on the lookout for new drugs or other useful chem- 

 icals that the microorganisms might produce. The 

 Tanana soil bacteria, for instance, thrive in cold and 

 phosphorus-limited conditions. Perhaps they make 

 proteins that could be useful in agriculture, medi- 

 cine, or even laundry — a bacterial enzyme that can 

 operate in cold, boreal soil might be able to improve 

 the stain-removing power of cold-water detergents. 



But are conditions still cold? It's hard to escape 

 what many read as signs of unusual warming at 

 these latitudes. We sniff smoke in the air, blown in 

 from a forest fire in the Yukon. By the end of sum- 

 mer 2005, the fire season has become Alaska's third 

 worst. And the all-time worst was just the year be- 

 fore that: in 2004, fires consumed 6.5 million acres 

 of Alaska, an area bigger than Vermont. On aver- 

 age, the state is two degrees Celsius warmer than it 

 was at the beginning of the twentieth century. The 

 average surface temperature of the Earth has 

 warmed by one-fourth that amount (a half degree 

 Celsius) in roughly the same period. 



Making a direct, causal link between the warm- 

 ing trend and changes on the ground is hard to do, 

 but investigators in Alaska have tallied a compelling 

 list of consistent phenomena. In addition to the 

 record fires, the growing season has lengthened, 

 while, paradoxically, the oil-drilling season has 

 shortened by about half (the tundra in the far north 

 must be frozen deep enough to support the heavy 

 rigs and traffic). Sea ice is also dramatically dimin- 

 ished; it reached a record low of 2 million square 

 miles in 2005. The melting of sea ice — about 

 400,000 square miles in the past decade or so — am- 

 plifies climate warming and its myriad effects, as 



open water absorbs heat that the ice would other- 

 wise reflect back into space. 



Insects such as spruce bark beetles, which histor- 

 ically have taken two summers to mature, now come 

 of age in one, creating explosive populations that 

 have chewed up temperature-stressed trees. Could 

 the alder canker be another effect of the stress on 

 plants? It's possible. This is clearly uncharted terri- 

 tory in the life of the boreal forest. 



At the Bonanza Creek Experimental Forest and mi- 

 crobial observatory, soil temperatures have ratcheted 

 up to such an extent in the past twenty years that the 

 mean annual temperature half a foot below the sur- 

 face is now above freezing. The warmer soil affects 

 the forest community and its microbial underpinnings 

 in yet-uncharted ways, and it affects the global car- 

 bon cycle as well. As permafrost thaws, the prediction 

 goes, microbial decomposers gain a huge new source 

 of organic material to consume. But how well the 

 little-known microbial communities will hew to the 

 prediction, and how much carbon could be released 

 from this historical carbon sink, remain to be seen. 



What microbiologists do know is that the changes 

 both above and below the ground will alter the mi- 

 crobial community in subtle ways. Inevitably, one 

 strain or another will outgrow the rest. If the "win- 

 ner" happens to be a microorganism with a knack 

 for virulent infection, more 

 pathogens such as the 

 canker could emerge. ] 

 taking yearly soil sam- 

 ples, microbiologists 

 are accumulating a 

 DNA record of the 

 microbial commu- 

 nities that might 

 come to reflect the 

 changing tempera- 

 ture and vegetation 

 of the sites. 



North of the Tanana 

 River, gentle bluffs border 

 the floodplain. To the south, the wall of the Alas- 

 ka Range lies obscured in haze. In between, the 

 braided river takes the path of least resistance 

 through the valley, creating the many rivulets and 

 side channels in its seaward push. In spite of the 

 seemingly timeless majesty of the place, everything 

 in this panorama is moving: the river, the moun- 

 tains, and the forest in all its stages. The lives of the 

 cells in the soil are shifting, too. Too little is known 

 of this complex and unseen world to begin to pre- 

 dict what will become of it — too little, that is, ex- 

 cept that it will bring surprises. □ 



60 



NAT UK A I HISTORY April 2006 



