Michael C. Rutherford

ACKDAT: a digital spatial database of distributions of South African plant species and species assemblages

The fieldwork that underpins John Acocks’ work on the Veld Types of South Africa, was recorded in a set of field notebooks, which were preserved after Acocks’ retirement. These are adequately geo-referenced to allow the construction of a relational database linking more than 7 000 species’ presence, abundance and site location data at more than 3 000 sites throughout much of South Africa. The database is described with reference to data quality, representivity and spatial precision. Some appropriate and inappropriate types of uses of the data are illustrated.

Nama-karoo veld types revisited: a numerical analysis of original Acocks' field data

This paper assesses Acocks’ veld types against a reclassification of his own data for the Nama-karoo using a suite of multivariate techniques. The analysis showed that the vegetation of Nama-karoo can be partitioned into three major clusters with the most clearly defined cluster corresponding to areas in the arid northwest. Within these clusters the species groups or pools substantiated a number of Acocks’ veld types and some of their subdivisions. Notable in this regard are the veld types Orange River Broken Veld and Arid Karoo as well as some of their subdivisions. The findings suggest that some of these subdivisions could well have been raised to full veld type status. Also confirmed was the nebulous nature of Central Upper Karoo and False Arid Karoo with gradual transitions to most neighbouring veld types. Not supported by the analysis are False Succulent Karoo and several veld types, or parts of veld types in the south-eastern Nama- karoo. Non-coincidence with the units of the numerical analysis in the latter area may also be a consequence of a mismatch between Acocks’ large sample areas and his relatively fine mapping scale in this particular region.