Ecology of the Subantarctic Islands: Botanical factors
Early visits to subantarctic islands were limited to a few days duration and the collecting of specimen material naturally took precedence. Cockayne (1903) and Laing (1909) wrote of the plant formations and associations and gave a remarkably complete picture of the vegetation of the day. Since that time certain aspects of the subantarctic flora have changed considerably although the essential elements are the same. In 1951 Oliver and Sorensen named the associations in accordance with the appearance of the vege- tation 50 years later.
Climatic Factors: Information obtained at Campbell Island from 1941-47 shows the rainfall to be not high, and with a yearly average of 57in., but the number of days of rain in a year to be excessive, 322. A low amount of sunshine is recorded, an average total of only 685 hours a year. The mean annual temperature is 44.2°F.; the mean monthly temperature is remarkably constant although the extreme range (highest maximum minus lowest minimum) is 41.3°F. Extremely strong north-west winds are experienced and relative humidity reaches high figures.