Surveying the growth of lichen on the surface of a boulder is part of an initiative to monitor 

 plant biodiversity in the high-alpine environment. Here Halloy (right) and Karina Yager, an 

 anthropologist with the expedition, sample the lichen density and variety at 17,200 feet in the 

 Cordillera Vilcanota with the help of a netted grid. 



Biologists have discovered unique communities of 

 insects living in the bark and debris around their 

 trunks; the insects, in turn, feed various bird species, 

 including Citiclodes aricomac, whose world popula- 

 tion is estimated at no more than a few hundred. 

 New species continue to be discovered among the 

 quehua, but some may not last long. In most places 

 the trees are being fast exterminated by woodcutting 

 and grazing, as roads penetrate more high places. 



Interspersed among the trees are bright green 

 lumps that I at first take for moss-covered boulders 

 [see photograph on page 44]. They are Azorella com- 

 pacta, nonwoody plants whose giant tap roots reach 

 deep underground. Aboveground, they produce 

 canopies of tightly packed rosettes that, like corals, 

 grow slowly outward in layers. Very slowly. Halloy, 

 who has studied them, points to a "baby" about 

 the size of a dessert plate. "Two hundred years," 

 he says. Later, we find another one about ten feet 

 across. "Two, maybe three thousand," he says. 

 They look cushiony, but their surface is as hard as 

 wood because of their dense growth and fortifica- 

 tion with superhard resins. 



Another thing about them: they likely retain 

 inner rings of old leaves — along with dust, debris, 

 and pollen trapped over the ages. "The scientist 

 who learns to read their insides will have the history 

 of the Andes laid out before him," remarks Halloy, 

 patting one behemoth. "Climate, volcanic erup- 



tions, vegetation, everything. Before the Inca. Be- 

 fore Christ." He raps on the surface with his knuck- 

 les. "Hey! Who's in there?" he laughs. 



As a group of us hike toward Sajama's snowcap, 

 we glimpse vicunas galloping in groups of 

 fours or fives over distant rises, then disappearing 

 without a sound, like ghosts. Covered in supremely 

 fine wool and able to bound up sheer slopes, they 

 seem perfectly adapted to their harsh surroundings. 

 But something has been catching up with them 

 even here: we have seen their carcasses in a dozen 

 places. Sajama hosts predators such as Andean foxes 

 and pumas, and there have been rumors of Andean 

 mountain cats — a species so secretive no one pho- 

 tographed a live one until 1980. Halloy and a part- 

 ner made the first photographs when they encoun- 

 tered one in northern Argentina and followed it for 

 a couple of hours. Yet curiously, the dead vicunas 

 we have seen appear untouched by predators. A 

 park ranger suggests they are being killed by light- 

 ning, but some of the scientists doubt lightning 

 could strike that often. 



The next afternoon we are spread across various 

 sites when the sky darkens and thunder booms. Up 

 this high, you are literally in the clouds — and thus 

 literally in the middle of the frequent electrical 

 storms generated by the ice particles circulating in 

 the clouds. Often the storms only growl and back 



September 2006 natural history 



49 



