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Within South Africa there is a growing need for a high resolution proxy rainfall record that goes beyond the historic record. As a contribution to meeting this need the relationship between rainfall and Widdringtonia cedarbergensis Marsh, ring width indices is re-evaluated. As opposed to the various Podocarpus sp. it is possible to develop an annual ring width chronology for Widdringtonia cedarbergensis. In the present study, two more chronologies are added to the single chronology already available for this species. The development of these well dated ring width index chronologies is hampered by a lack of an abrupt termination of late wood growth in many of the trees utilised for this study. Despite this limitation the results show that with a large enough sample size it is possible to develop well-dated ring width indices from Widdringtonia cedarbergensis. Correlations between ring width indices and rainfall are not sufficiently high to reconstruct rainfall through time.

Seeds of 13 Aspalathus species and three other Fabaceae species from the fynbos vegetation of the Western Cape Province, South Africa were exposed to pre-germination treatments comprised of combinations of four different temperatures (60 °C, 80 °C, 100 °C, 120 °C) and three time durations (5, 15 or 30 minutes). The ‘heat-sum’ (product of temperature and time) most effective in stimulating germination in a particular species was shown to be negatively correlated with a specific seed characteristic, namely the proportion of whole seed to embryo plus cotyledon mass. It may thus be possible to predict the temperature-time combination most effective for stimulating germination in Aspalathus species and possibly other members of the Fabaceae by using this ratio. However, predicting the number of seeds likely to germinate in the field after fires of different intensity requires further information concerning the distribution of seeds in the soil which is currently unknown for fynbos legumes.

The Cape Floristic Region of South Africa is an area of diverse substrata, high species diversity and complex vegetation patterns. Fynbos vegetation and soils were sampled at 75 sites in a 30-ha study area in the Soetanysberg hills in the south-western part of the Western Cape Province. TWINSPAN, DCA and CCA were used to investigate vegetation patterns and vegetation-environment relationships (with emphasis on soil factors). Classification of the vegetation data, which included 251 species, identified five communities associated with distinct soil types and DCA suggested two main compositional gradients. CCA showed that these two gradients were associated with environmental gradients of pH, soil depth and soil texture. When sites associated with the three substrata, namely, limestone, sandstone and colluvial sand, were analysed separately by CCA, only sandstone and colluvial sand produced significant vegetation-environment relationships. Despite the edaphic complexity of this landscape and the very large number of species, this study showed that there is predictable structure in the vegetation, related to various environmental factors, particularly at the community level. Die Kaapse Floristiese gebied bestaan uit diverse substrata, ‘n hoe spesiediversiteit en komplekse plantegroeipatrone, Fynbos plant- en grondmonsters is op 75 persele in ‘n 30-hektaar gebied in die Soetanysbergheuwels van die Suid-westelike Kaapprovinsie geneem. TWINSPAN, DCA en CCA is gebruik om plantegroeipatrone en piantegroei-omgewingsinteraksies na te gaan met klem op grondfaktore. Die 251 spesies is in vyf gemeenskappe gegroepeer wat met definitiewe grondfaktore geassosieer is, Twee hoofsamestellingsgradiente is geidentifiseer, Voigens CCA is hierdie twee gradiente geassosieer met grond pH, gronddiepte en grondtekstuur. Toe persele wat op die drie substrata (kalksteen, sandsteen en kolluviafe sand) voorkom, afsonderlik met CCA ontleed is, hetslegs sandsteen en kolluviale sand betekenisvolle plantegroei-omgewingsverwantskappe getoon. Ten spyte van die edafiese kompleksi-teit van hierdie gebied en die groot aantal spesies, dui hierdie Studie aan dat, veral op die gemeenskapvlak, die plantegroeistruktuur op grond van verskillende omgewingsfaktore tog voorspefbaar is.

Results are presented of nitrogen input via bulk precipitation over a two-year period, to coastal fynbos vegetation occurring on soils of low nutrient status. The annual precipitation recorded during the study periods of 1980 – 81 and 1981 – 82 was 381 mm and 466 mm respectively which was below the 40-year mean of 577 mm recorded for the area. Total nitrogen input during 1980 – 81 was 1,99 kg N ha − 1 y − 1 . Of this 1,12 kg N ha − 1 y − 1 was inorganic nitrogen in the form of NO 3 -N and NH 4 -N. Inorganic N input occurred predominantly in the winter rainfall months of June to August. Inorganic N input during 1981 – 82 was 1,79 kg N ha − 1 y − 1 with an NH 4 -N to NO 3 -N quotient of 1. Logarithmic relationships exist between NO 3 -N and NH 4 -N concentrations in bulk precipitation and the volume of precipitation collected at weekly intervals. Bulk precipitation collectors at 1,5 m and 4 m were not suitable to determine the infuence of local recycling of dust aerosols. It is probable that although atmospheric N deposition may contribute a portion of the extra-system N, it alone is not sufficient to replenish N lost by coastal fynbos ecosystems as a result of recurrent short interval fires. Rather the low input of nitrogen to the Pella site reported gives an indication of the levels of N deposition to be expected in the fynbos region where N is derived mainly from oceanic sources and few anthropogenic activities influence precipitation composition.

The inhibition of in vitro nitrate reductase activity in extracts of Protea spp. is shown to be due to polyphenolic constituents of the roots and shoots of the plants (which can be adsorbed by insoluble polyvinylpyrrolidone) rather than to the activity of endogenous proteases. The in vitro nitrate reductase activity in shoots of Protea repens and Protea cynaroides fed 2 mmol dm − 3 NO 3 − for 24 h prior to nitrate reductase extraction show a nitrate reductase activity of 2–4 μ mol NO 2 − h − 1 while the roots of P . repens show an in vitro nitrate reductase activity of 0,2 μ mol NO 2 − h − 1 (g fresh mass) − 1 . The low nitrate reductase activity of these plants possibly reflects their adaptation to growth under the low nutrient condition of the soils of the South Western Cape, South Africa.