Predicting the distribution of fynbos and succulent karoo biome boundaries and plant communities using generalised linear models and geographic information systems

Abstract

Vegetation survey data from Matjiesrivier Nature Reserve, in the eastern Cederberg Mountains of the fynbos biome, were used to model the distribution of fynbos and succulent karoo biomes and plant communities. Predictions were based on generalised linear models (GLMs) with the presence or absence of a biome or community as the response variable. Geology, altitude, radiation and landtype, which were derived from remotely-sensed sources (maps, aerial photographs and digital terrain models), were used as explanatory variables in the GLMs. The boundary between fynbos and succulent karoo could be predicted accurately based on geology and altitude alone. Fynbos occurred on sandstone above 800 m; succulent karoo occurred on sandstone below 800 m, or on shale at any altitude. Community distributions were less accurately predicted, but could be used to generate a geographic information system (GIS) map similar to a vegetation map derived from ground survey. These models can be used to map vegetation over large areas in the fynbos/succulent karoo ecotone with relatively little effort or cost.