HISTORY AND DESCRIPTION OF CONTEMPORARY VEGETATION, SIGNAL HILL, CAPE TOWN

CHRISNA JOUBERT

Thesis submitted for the degree of Master of Science (Botany) at the University of Cape Town
April 1991

ABSTRACT

Signal Hill is a 2,5 km long ridge above Cape Town. It forms the northern extremity of the Cape Peninsula Mountain Chain and is included in the Table Mountain Nature Reserve.

The study area is situated on the north-west, north and south-east facing slopes of Signal Hill, ranging between 120 m and 350 m above sea level. Rain falls mainly in winter with an annual mean of some 463,5 mm, while the summer is generally hot and dry. Winds are mostly north-westerly in winter and south-easterly in summer. Soils are usually cobbly with generally 10-25% clay in the topsoil overlying shale rock. The vegetation is considered to be West Coast Renosterveld.

A study was made of the historic land use of the area. In the 18th century farms were established on the lower slopes. From 1895 the higher altitudes were utilised by the Municipality of Cape Town for commercial forestry mainly with pines and eucalypts until the area was proclaimed a nature reserve in 1 964. A map to indicate the possible sites of these plantations was compiled.
A phytosociological study based on the collection of vegetation and environmental data from 53 randomly stratified releves over an area of 1 24 ha was carried out. The survey was extended over 12 months to ensure the inclusion of as many plant species as possible after which a list of the vascular plant species was compiled. A total of 81 families, 255 genera and 460 species was identified. The phytosociological method revealed that only one major plant community occurs in the study area, and two sub-communities with a total of five variants correlated mostly with aspect were identified. The perennial species were analyzed separately from the ephemeral species to determine the contribution of each group towards the vegetation types, and both data sets gave similar classifications. A vegetation map was also compiled.

Regarding the biogeographical study, the plant lists of five Renosterveld localities were compared at the family, genus and species level in an attempt to determine the relationship among the localities. The flora of a Coastal Renosterveld, mixed Mountain Renosterveld and Karoo, Mountain Fynbos, Strandveld and Forest site derived from phytosociological tables was compared at the family and genus level to illustrate the relationship among the five localities.

Finally recommendations for the future management of the study area are given.

tonyrebelo Added by tonyrebelo on December 09, 2017