Browsing by Author "Cowling, R. M."

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    Do insect distributions fit our biomes?
    (Academy of Science for South Africa, 2007) Proches, S.; Cowling, R. M.
    An assessment of biome-specificity in southern African insect assemblages was undertaken using sweep collections in fynbos, grassland, subtropical thicket and Nama-karoo. Insect samples from the same biome generally cluster together in multidimensional scaling analyses, although there is a great variability between sites within each biome. Rich and distinctive insect faunas exist in each biome, including fynbos. In the Baviaanskloof Conservation Area of the southeastern Cape, where the four biomes marginally co-occur, some insect assemblages are enriched relative to sites at the core of the biomes, presumably through the mixing of faunas via transient or persistent establishment of populations recruited from adjacent biomes.
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    Water-use characteristics of Palmiet (Prionium serratum), an endemic South African wetland plant
    (South African Water Research Commission, 2020) Rebelo, A. J.; Jarmaln, C.; Esler, Karen J.; Cowling, R. M.; Le Maitre, D. C.
    ENGLISH ABSTRACT: Palmiet, Prionium serratum, is an endemic wetland plant which dominates oligotrophic wetlands throughout the Cape Floristic Region, South Africa. Palmiet is often perceived as undesirable by landowners, in part because it is thought to have high water-use, although little is known about the water-use of this important wetland species. We estimated the water-use dynamics of Palmiet at the leaf scale, using stomatal conductance measurements, and at the wetland scale, by modelling evapotranspiration using remote sensing and an energy-balance model. Factors that influenced Palmiet water-use were also considered, and seasonal variations were analysed. The aim was to estimate Palmiet wetland water-use, and to develop a set of crop factors (Kc) for use in hydrological modelling of catchments containing Palmiet wetlands. Results show that Palmiet has a comparatively low stomatal conductance (11–152 mmol∙m-2∙s-1), which was lower in summer than winter, and moderate evapotranspiration for a riparian species (1 220 mm∙a-1 compared to a local reference evapotranspiration of 1 302 mm∙a-1 and A-Pan evaporation of 2 809 mm∙a-1), which was higher in summer (more energy to drive evapotranspiration and higher vapour pressure deficits). Morphological and physiological adaptations to nutrient poverty or periodic drought are suggested theories which may explain the controls on transpiration for Palmiet.