| Summary: | The seasonal change in the standing crop of Ranunculus penicillatus var. calcareus in a section of a chalk stream was measured. The plant is a herbaceous perennial which regrows each autumn and winter. It grows rapidly in the spring, then flowers, this coincides with a decline in the growth rate, and results in a maximum biomass in mid-summer of 200 - 400 g dry weight m2. After this the plant starts to decompose and the remainder (18%) is washed out in the first autumn rains. Although 10 - 15% of the maximum biomass of the plants is lost, mostly by damage to stems, about half' of' this is collected on plants immediately downstream and only 7% of the maximum biomass is lost as stems from the stretch. The leaf-fall was about 8.5% of the maximum standing crop and decomposed where it dropped. decline in the maximum standing crop of the plant is found as a result of not removing the plant in the early summer, as is typical of normal river management to reduce flood risk.
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