THE VEGETATION OF THE JUAN FERNANDEZ ISLANDS 895 



The valleys of Villagra. This wide and well-watered valley sj'stem 

 harbours some of the best upper montane forest left on the island; precipitation 

 is, as far as we were able to judge, higher here than on the north slopes. Some 

 maqui is found in the ravines, but there is no macal of any significance. Toward 

 the sea, from the foot of El Vunque to the spur separating Ouebrada de la 

 Choza from the Chumacera valley, the forest ends abruptly in a sharp line. 

 220 — 225 m abo\e sea-level (PI. 85: i). I regard this line as a climatic seaward 

 timber-line, because I find it difficult to believe that under the present climatic 

 conditions the forest ever went farther down. The vegetation below the forest 

 . is xerophilous grassland (St. 43) with ston\- tracts with open, dwarfed scrub (St. 44)- 

 Most of the rain falls over the ridges surrounding \'illagra Bay, and only along 

 the water-courses is a closed fringe of bright green (hinnera peliata, well set oft' 

 against the \-ellowish grass and the silver gray Acaena (PI. 85: 2). Wind is another 

 important factor, likely to force the forest back, and the edge is wind-trimmed. 



Our camp was situated on a low spur between two streams almost over- 

 grown with Giinnera (PI. "j^: 2), about 175 m above the sea. On the spur, be- 

 tween the camp and the edge of the forest, low shrubs formed a scrub (PI. 91), 

 with Escalloiiia, Cuuiiiiia feDiaJidezia, Margyricarpus, Robhisoiiia gayaiia, Tliyrsop- 

 teris, Dryoptcris viaequalifolia, PolysticJiur,: herteriaiiuui, BlecJniUDi ScJiottii, B tonus 

 feniandezimius and Peperotnia berteroana, a very unusual assemblage at such a 

 low altitude, for several of them an absolute record. The Choza forest is of typical 

 lower montane type, tall-stemmed, dark and with poorly developed undergrowth 

 (St. 5, Pis. 94: 2, 95: i). It ascends to about 400 m, where it meets the precipice 

 of the ridge; water trickles down over the rocks, where a few rosette-trees and 

 patches of Cladiuui, typical of such localities, have gained a foothold. In the 

 main Villagra valley, maqui extends down to c. 160 m. From about 400 m the forest 

 assumes the character of the upper montane t\-pe (St. 13 1. Dicksonia, Thyrsopteris 

 and WeymoictJiia are common, below the pass Lactoris is in its prime, and the 

 vegetation passes into the clift" forest already mentioned. 



On the west flank of Y\ Vunque a small hanging valley is accessible to about 

 500 m above sea-level, where a vertical cliff wall checks further advance. The 

 forest had been thinned, I don't know for what purpose; there were numerous fallen 

 trees and many dead ones still standing, and the ground had been grazed. Above 

 approximateh- 400 m undamaged Dicksonia-Weyinoiithia-iox^sX. was met with, with 

 thick-stemmed bamboo, Lactoris and seven species o'i Hymenophyllaceae \^l. 14). 



From Villagra to Punta Larga. Proceeding west from Villagra, the 

 last forest patches are encountered at the foot of Cerro Chumacera, two small 

 groves of a poor luma forest with some members of the Robivsonia assemblage 

 (St. 23), and below, at the foot of a projecting cliff, where water comes down 

 also during the dry season, a small Boe/i»ieria gro\e (St. 10). These groves are 

 seen in Fig. 36. West from here the country is treeless grass-land, nearer to \'\\- 

 lagra mainly native Stipetion (PI. 100), farther west \z.x^^ 2.x^2l?> o'i Aveiia barbata\ 

 Acaena is common, but becomes scarce toward Punta Larga. Upon the whole, 

 I got the impression that native species play a much greater role in the composition 

 of the grass-land on this side than on the north side of the island, where intro- 



