Litterfall and Decomposition Processes in the Coastal Fynbos Vegetation, South-Western Cape, South Africa

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Abstract
(1) Random litterfall and litter production and decomposition of Leucospermum parile and Thamnochortus punctatus were monitored between 1981 and 1983 in a 5-7-yr-old stand of coastal fynbos, south-western Cape, South Africa. This vegetation has a characteristic physiognomy consisting of proteoid, ericoid and restioid elements. (2) Annual litter production was 84 and 72 g m-2 during 1981-82 and 1982-83 respectively with summer-autumn being the main period of litterfall; the major litter came from the ericoid elements. No differences were found in fats and waxes, soluble carbohydrates, soluble phenolics and total nitrogen between leaf litter of proteoid and ericoid elements and culm litter of the restioid elements. (3) Mean annual litter production under the canopies of L. parile was 357 and 429 g m-2 during 1981-82 and 1982-83, respectively, with 51-58% being leaf litter. Seasonal variations were found in the methanol-soluble carbohydrates (summer maximum) and lignin (winter maximum) in the leaf litter of L. parile and a withdrawal of 41% nitrogen and 25-50% phosphorus was calculated during leaf abscission. (4) Female plants of T. punctatus had an annual litter production of 23 g m-2 compared with 12 g m-2 for males. The main litter category from both sexes was inflorescence parts. Holocellulose was the main organic constituent in fertile culm litter of both sexes of T. punctatus and the restioid group generally. (5) Turnover times of dry mass were calculated to be 14.5 and 11.4 yr for leaf litter of L. parile and sterile culms of T. parile and sterile culms of T. punctatus, respectively, but male flowerheads of T. punctatus showed no significant decay. (6) Methanol-soluble carbohydrates, phenolics and holocellulose declined at approximately similar rates in decomposing leaves of L. parile. Changes in nitrogen and phosphorus contents in decomposing leaves of L. parile were negligible but accumulations of potassium, magnesium, calcium and iron were demonstrated. (7) These results are compared with those of other mediterranean-type ecosystems. The frequent fires in the fynbos vegetation may preclude the development of a steady-state litter.