n Fitososiologiese studie van die Hester Malan-natuurreservaat

Abstract

The main aim of this study was to classify and describe plan.t communities in Hester Malan Nature Reserve using the Braun-Blanquet method. The vegetation of the Hester Malan Nature Reserve was also brought into context with the vegetation of the North-western Cape, and placed in an AcocKs Veld Type, the Namaqualand Broken Veld. The differences in the ephemeral vegetation between two years were determined, as well as the ratio between the ephemeral and the total vegetation of the Hester Malan Nature Reserve. The North-western Cape can be physiographically subdivided into a) a lowlying annual flat area, rainfall next to the coast and in the south, with an average between 0 and 150 mm, b) a mountainous central area with an average annual rainfall between 100 and 400 mm and c) a plateau in the east with an average annual rainfall of between 50 and 150 mm. The first two areas represent Namaqualand which is locally divided into the Richtersveld, the Sandveld, the Namaqualand Rocky Hills and the Knersvlakte. The plateau area is Known as Bushmanland. Western Mountain Karoo, Arid Karoo and Desert False Grassveld, Succulent Karoo, Orange River Broken Veld, Namaqualand Broken Veld, Strandveld of the West Coast, False Succulent Karoo, Mountain Renosterbosveld and Fynbos (AcocKs, 1975) is found in the North-1A1estern Cape. A phytosociological table, compiled from data obtained by means of a line transect survey, identified three communities in the Namaqualand Broken Veld, three communities in the Strandveld of the West Coast and one community in the Arid Karoo. Although the first two Veld Types receive predominantly winter rain and the latter predominantly summer rain, a floristic relationship between the two areas The Hester Malan Nature Reserve is situated in the Namaqualand Rocky Hills near Springbok and receives an average annual rainfall of 162 mm. The vegetation was classified using the Braun-Blanquet method. Floristic, structural, habitat and soil data was collected for 223 releuds and analysed into a phytosociological table, distinguishing four communities with two facies in the rocky hills and four communities with six facies in the flat areas with less or no rock. These communities were based on perennial species that were always present above ground. Ephemeral vegetation of two years were compared with each other with the aid of the Braun-Blanquet method and similarity indices. During the two years studied, the annual rainfall was 87,5 mm and 267,0 mm. Differences were found in comparable) ephemeral dominance differences vegetation 1 71 the dominance (constancy and cover) of the species (56% rather than in the species composition (75% comparable). The associations also differed in the two years. Differences in are therefore responsible for the well Known yearly physiognomic of the ephemeral vegetation in Namaqualand. The ephemeral consisted of about 10% of the total vegetation cover of the Hester Malan Nature Reserve. A list of 611 plant species occurring on the Hester Malan Nature Reserve was compiled 1,1Jith 14 species, 8 genera and 6 families in the Bryophyta; 5 species, 3 genera and 2 families in the Pteridophyta, and 592 species, 25 genera and 61 families in the Angiospermae.