Tussock grass has colonized an ice-free corridor of terrain that has opened up in the past quar- 

 ter century because of the recession of an ice cliff. The corridor, now about 250 yards wide, lies 

 at about 1 7, 700 feet in the Cordillera Vilcanota. 



formed, having been swept up on persistent air 

 currents — as it continues to be — from subtropical 

 lowlands. The pollen grains, as many as 55,000 in a 

 quart of meltwater, nourish fungi. I was immedi- 

 ately reminded of Lawrence W. Swan, an alpine 

 biologist who studied the Himalayas in the mid- 

 twentieth century: some insects and spiders there, 

 he noted, subsist on a manna of lowland plant frag- 

 ments and live prey. Swan named an entire new life 

 zone for its dependence on that curious food 

 source: the Aeolian biome, after Aeolus, Greek 

 god of the wind. 



Schmidt's research also suggests that various bac- 

 teria live off the underlying rocks, depositing acids 

 that dissolve out nutrients. Those nutrients then 

 pass into the ground to fuel successor communities. 

 Just beyond the ice front we found the water gooey 

 with photosynthetic cyanobacteria. On bare sand, 

 their dark masses were building into crusts, to form 

 the beginnings of soil. Not much farther on, a few 

 plants were taking root. 



In places less recently plowed by ice, plants 

 bloomed everywhere. On the first day at our study 

 area near one of our campsites at the valley's head, 



Halloy's colleague Alfredo Tupayachi, a biologist at 

 the National University of San Antonio Abad in 

 Cuzco, discovered what he declared to be the 

 world's highest known orchid. The plant is a 

 diminutive relative of lowland species, growing 

 along a mossy seep at 16,240 feet. Like most alpine 

 plants (including the potato, a high Andean native), 

 it is small, low-lying, and covered with insulating 

 hairs, and it keeps most of its mass below ground. 



The next morning we ascended a knife-edge 

 moraine to a windy 17,200-foot summit of 

 bedrock riven with cracks. It was still dusted with 

 snow, which falls almost every night, then melts 

 off in the fierce, unfiltered morning sun. After just 

 a few hours of work, Tupayachi and Halloy 

 counted sixty-two species of vascular plants, 

 mosses, and lichens, including a few probably new 

 to science. The regular snowfall may actually help 

 the plants, Halloy said; it insulates them from sub- 

 freezing nights, then feeds them meltwater w hen 

 the sun appears. 



In among the flowers buzzed darkly colored 

 ground-nesting bees. Lowland species cannot move 



September 2006 natukai hisiory 



4 7 



