Shoots ofScirpus maritimusvar.paludosussprout from overwintered tubers in May. Stem growth is rapid and within 2ndash;3 weeks lateral rhizomes extend outwards and produce tillers with new tubers at their bases. By August up to four new shoots are produced in a rhizomendash;shoot series. All aboveground biomass is dead by late October but tubers overwinter to develop the following growing season. The ratio of below- to above-ground biomass of the rhizomendash;shoot series increased from 0.20 to 0.76 from early to late summer. The ratio of below- to above-ground biomass of individual stems was highest at the youngest end of the rhizomendash;shoot series.Stem density and inflorescence and total biomass were monitored at three sites over three growing seasons. The sites had large fluctuations in salinity in response to changes in water depth. Among all sites, maximum stem density reached 380ensp;stems/m2by late July, slightly before the maximum standing crop of 625ensp;g/m2was attained. At one site, changes in water levels and salinity increased the peak aboveground standing crop 22-fold (from 27 to 600ensp;g/m2) from 1978 to 1979. A mathematical equation predicting the seasonal aboveground standing crop ofS. maritimuswas developed using water depth and conductivity as predictor variables.
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