THE VEGETATION OF THE JUAN FERNANDEZ ISLANDS 805 



1917 April II. Ascent of Cordon Centinela to the point where it branches off from the main 



ridge, alt. about 780 m. Rediscovery of Bertero's "Tillandsia" , now Hesperogreigia 



Berteroi. — 10 hrs. 

 » » 12. To Porteziielo and upper slopes of Villagra. — 6 '/a hrs. 



» » 14. To Porte/uelo. — 4 hrs. 



» .» 17. Along trail towards Puerto Frances, up Cordon Chifladores and west branch of 



Frances Valley to 500 m alt. — 11 hrs. 

 » » 20. A. M. Portezuelo and north wall of Cerro Pinimide. — 5 '/z hrs. 



» » 21. P. M. Cordon Sulsipuedes. — 5 hrs. 



» » 24. Across Portezuelo and down into east part of Villagra; ascent of one of the 



buttresses of Yunque to foot of a vertical wall, about 500 m alt., returning same 



route. — 8 hrs. 

 » » 30. Sailed for Valparaiso. 



ClIAI'TKK I. 



Environmental factors. 



Te))iperatiire a7ni raijifall. 



The single meteorological station is situated in the settlement in Bahia Cum- 

 berland where observations were begun in 1901, but the gaps are many, and 

 no dates after 1942 have been available. From 1901 to 1922 inclusive the sta- 

 tion was situated 10 m above sea level, and from 1929 at 6 m, the Subdelegado 

 civil being in charge. The difference in elevation being insignificant, the two 

 series have been treated as one. From June, 1923, to end of 1928, the altitude 

 was 345 m; the locality, not indicated in the Anuario, was, I suppose, the Cent- 

 inela Radio Station. Our only aneroid reading, 355 m, is probably a little too high. 



The dates available, incomplete as they are, give a good idea of the climate 

 of the basal region on the north side of central Masatierra; see Table I. 



In 1914 (Skottsb. j) I published figures for 7 years (1901 — 1907) but com- 

 plete for 5 only: mean annual temp. I5°.6C., means of daily max. and min. 18°. 8 

 and 13°. 5, average rainfall 1081mm. Whereas the temperature figures are about 

 the same as in the table below, the difference in rainfall is considerable. This 

 is not surprising, because the variation from year to year was very great during 

 the period 1901 — 1942, from 317.7 in 1901 to i 697.7 in 1922, both figures being 

 very exceptional, as shown by the graph. Fig. i. 



These observations tell us nothing about the climate in the montane region 

 where the rainforest and mountain scrub cover the slopes and ridges, but some 

 conclusions may be drawn from the short series obtained in 345 m altitude. Table 11^ 



The figures from the two stations are not directly comparable, because the 

 observations were not taken simultaneously; nevertheless, the difference in temp- 

 erature is clear enough. No reliable conclusions can be drawn from the observed 

 difference in the amount of precipitation. 



As was mentioned above we put up a small weather station in the Porte- 

 zuelo pass, where readings were taken every second day between March 25 and 

 April 30. The elevation generally given is 550 m, while the average of our 



