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Community regulation in Phragmites communis Trin.. II. 1971. Mixed stands. Journal of Ecology. 59, 75—88.

SUMMARY

Stands of mixed Phragmites communis Trin. and other species are commonest in drier marshes and other places where interference has prevented carr development. P. communis is a poor competitor, particularly with species of dry eutrophic marshes, and grows best where these are excluded by flooding or nutrient deficiency. P. communis suppresses other plants by shading, where it can grow dense and tall enough to do so, and is itself suppressed by a thick litter mat and a below-ground control which make reeds sparse and, in extreme cases, short.

Where P. communis is decreased by nutrient deficiency or damage to shoots or rhizomes, its competitors can increase. Where shading, litter, water level, nutrient status, aeration, burning or disease harm the competitors or selectively favour P. communis, this increases. Where shading, lodging, litter, below-ground control, growth rate or nutrient status harm P. communis or selectively favour competitors, they increase.

The final balance of dominance depends partly on physical factors and inherent features of the plants, e.g. soil and water regime, growth form, size and presence of propagules of the species; partly on the physiological attributes of these species, e.g. shade-tolerance, below-ground control, the nature of the population (advancing or hinterland), and tolerance of propagules to establishment conditions; and partly on historical accidents or events, e.g. opening of litter mats, diseases, and the nature of the human interference.