Effects of thirty-five years of afforestation with Pinus radiata on the composition of mesic mountain fynbos near Stellenbosch
Annotatsiya
The fynbos vegetation of Biesievlei, Jonkershoek, was surveyed and described in 1945. In 1948 the catchment was afforested with Pinus radiata. This paper presents results of a reassessment of the vegetation in 1984 using the same methods that were used in 1945. Afforestation has reduced the cover of the vegetation (excluding P. radiata) from 75% to 20%. The total number of species was reduced by 58% from 298 to 126. At least 190 species found in 1945 were not found in 1984, and at least 18 species were added to the list. The mean plant density was reduced from 260 to 78 plants m− 2. Only stream bank vegetation, comprising mainly large-leaved sprouting shrubs, persisted in a relatively unmodified state. Away from the stream, annuals, geophytes and hemicryptophytes were dominant. Dominant species in the pre-afforestation flora were not resilient to afforestation. Serotinous Proteaceae, woody small-leaved sprouting and myrmecochorous shrubs and large-leaved sprouting shrubs have been virtually eliminated. Certain groups may re-establish after clearfelling, but others, notably various groups of shrubs may have been permanently eliminated. The implications for weed control in conservation areas are discussed. Die fynbos-plantegroei van Biesievlei, Jonkershoek is in 1945 ondersoek en beskryf. Die opvanggebied is in 1948 met Pinus radiata bebos. In hierdie artikel word die resultate aangebied van 'n 1984-heropname van die plantegroei waarin dieselfde metodes gebruik is as dié in 1945. Bebossing het die plantegroei-bedekking (P. radiata uitgesluit) vanaf 75% tot 20% verminder. Die totale aantal spesies is met 58% verminder, van 298 tot 126. Ten minste 190 van die spesies wat in 1945 gevind is, is nie weer in 1984 opgemerk nie en ten minste 18 spesies is bygevoeg tot die lys. Die gemiddelde plantdigtheid is verminder vanaf 260 na 78 plante m− 2. Slegs oewerplantegroei, hoofsaaklik herspruitende struike met groot blare, het bly voortbestaan in 'n relatief onveranderde toestand. Weg van die stroom, was jaarplante, geofiete en hemikriptofiete dominant. Dominante spesies in die voor-bebossingsflora was nie bestand teen bebossing nie. Serotiene Proteaceae, houtagtige, smalblaar, spruitende en mirmekochore struike en grootblaar, spruitende struike is so te sê geëlimineer. Sekere groepe mag hervestig na kaalkap, maar andere, veral verskeie groepe struike is dalk permanent verdring. Die gevolge vir onkruidbeheer in bewaringsgebiede word bespreek.