, Volume 79, Issue 1-2, pp 89-97

Response to nutrient additions by the plant growth forms of sand-plain lowland fynbos, South Africa

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Abstract

The growth response (foliage projective cover: FPC) of the plant growth forms of lowland fynbos, South Africa to a complete factorial fertilizer addition of nitrogen (N), phosphorus (P) and a mixture of all essential nutrients excluding N and P (M) was monitored for two years. Ordination by correspondence analysis revealed a successional trend as the vegetation aged, with increases in proteoid, and to a lesser extent restioid, and decreases in reseeding ericoid, graminoid, geophyte and annual plant FPC but no discernible effects due to fertilizer application. Analysis of covariance revealed significant increases in restioid, graminoid and annual plant FPC with N-addition, 1 and 2 yr after fertilizer addition and of total FPC with N-addition for only one year. Of the other nutrient treatments, only an increase in annuals with P-addition and a reduction in the rate of decline of reseeding ericoid with M-addition were found, both after two years. Thus nitrogen may often limit vegetative growth of at least the herbaceous species. The herbaceous growth forms are more plastic in their morphological growth responses to nutrient additions than the slow-growing, stress tolerant, evergreen shrub species. The vegetation appears to be resilient, at least in the short-term, to a disturbance of this magnitude. However, chronic nutrient applications and those of larger magnitude will probably result in long-term changes in species composition, with an increase in ephemeral, nutrient demanding species.