Aspects of coastal fynbos phenology

This thesis comprises three papers on different aspects of the phenology of several south western Cape coastal fynbos species, with a general introduction and conclusion I inking the three. The introduction discusses factors relating to the occurrence of summer growth in some Australian heath and Cape fynbos species. The first paper deals with the responses of the stem xylem pressure potential of two species to seasonal moisture changes in three soils. The results show that L. parile experienced little or no water stress throughout the investigation. The decreasing spring-summer potentials measured in T. punctatus suggest considerable water stress in this species. The observed differences can be explained in terms of species rooting depth and soil water-holding capacity. The second paper investigates patterns of seasonal shoot or culm growth in 11 species, in relation to past and present climatic factors and seasonal nutrient availability. The results show that other factors such as root depth and extent, plant age and water-use, and soil water-holding capacity affect the timing of shoot or culm growth in some species. In the final paper the seasonality of reproductive activity is discussed in relation to the seasonality of vegetative growth and to biotic and abiotic environmental factors. Reproductive activity appears to have little effect on the growth of individual shoots or culms. More research is needed to determine the effects of biotic pollinators, dispersers and predators as well as temperature, photoperiod and soil moisture on the seasonality of reproductive activity. In the conclusions summer growth is discussed in relation to water stress, seasonal availability of nutrients and to plant characteristics such as root depth and age