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Effects of season of burn on species populations and composition of fynbos in the Jonkershoek valley

1987; Elsevier BV; Volume: 53; Issue: 4 Linguagem: Inglês

10.1016/s0254-6299(16)31418-1

1727-9321

David C. Le Maître,

Botany, Ecology, and Taxonomy Studies

Data from a replicated plot experiment laid out to evaluate the responses of plants to season of burn are analysed. The initial results were published by C.L Wicht in 1948, but the results of subsequent surveys were not published. Plant densities were affected by the month in which the vegetation was burnt. Seedling densities were closest to parent plant densities after fires from January to April. The seasonal trend was strongly influenced by the effects of an unusually dry summer during 1945 and a low winter rainfall in 1946. Species richness and turnover differed after fires in different months. The smallest changes in species composition occurred after fires from December to April. The seasonal trends were also strongly influenced by the rainfall patterns during 1945 and 1946. Four uncommon species (one exotic) were not found again in the post-fire surveys and twenty new species (one exotic), including geophytes, first appeared after the fires. Forty-three species were recorded in all the surveys and a further seven species were not consistently recorded. A total of seventy-four were recorded in the surveys analysed. The highest number of species was found in young vegetation and the numbers declined with age, a pattern which fits the inhibition model of plant succession. Data van ’n gerepliseerde proefneming, wat uitgelê is om die invloed van brandseisoen op plante te bestudeer, word ontleed. Die aanvanklike resultate is in 1948 deur C.L. Wicht gepubliseer, maar die resultate van daaropvolgende opnames nooit. Die digtheid van plante na die brand is beïnvloed deur die maand waarin die plantegroei gebrand is. Saailingdigthede na Januarie tot April brande was die naaste aan die oorspronklike ouerplant-digthede. Hierdie seisoenale neiging is sterk beïnvloed deur ’n ongewoon droë somer gedurende 1945 en ’n lae winterreënval gedurende 1946. Spesie-rykheid en spesie-omset het verskil na brande in verskillende maande. Na brande in Desember tot April was daar die kleinste veranderings in spesie-samestelling. Hierdie seisoenale patroon is sterk beïnvloed deur die reënvalpatrone gedurende 1945 en 1946. Vier skaars spesies (een uitheems) het nie na die brande in opnames voorgekom nie en twintig nuwe spesies (een uitheems), geofiete ingesluit, het na die brande verskyn. Drie-en-veertig spesies was aanwesig in al die opnames en ’n verdere sewe spesies was nie deurgaans teenwoordig nie. ’n Totaal van vier-en-sewentig spesies is waargeneem in die ge-analiseerde opnames. Die grootste aantal spesies het in jong plantegroei voorgekom en die getal het afgeneem namate die plantegroei ouer geword het, ’n tendens wat die inhibisie-model van plantsuksessie pas.