Environmental Determinants of Island Species Numbers in the British Isles

Regression analyses were computed for the prediction of island species numbers in the British Isles, using as independent variables island area, island elevation, the number of soil types, ON latitude, the distance from mainlanid Britain, the distance from the nearest other island, the number of vegetation types, and latitudinal range. In simple regressions, the number of island soil types was the best single predictor of island species number. In multiple regressions, area, ON latitude, and distance from Britain also made significant contributions to the prediction of island species numbers. These analyses are discussed in terms of the theory of island biogeography in general and the description of the British Isles in particular. The slope of the log species, log area curve reveals that the plant species distribution pattern on the British Isles is more like that of continents than of islands.