Water levels andPhragmites: Decline from lack of regeneration or dieback from shoot death

This contribution combines field observation with the literature to argue that stabilised water levels are contributing to reed decline through a lack of vegetative and generative reproduction, and that eutrophic conditions exacerbate this situation. The focus on what causes reed shoots to die has increased our knowledge of what limits the distribution of reed without necessarily increasing our understanding of reed decline. This raises the question as to whether reed beds are in fact dying, or whether reed decline is observable only in the absence of regeneration. The distribution pattern and life-history of reed suggests that generative reproduction is lacking. It is proposed that the temporal at which seedling establishment takes place is similar to the time-frame of observed reed decline (10–50 years). As an “encompassing” factor, water regime influences many of the specific factors under investigation. Its role is therefore consistent with agreement in the literature that reed decline is caused by combinations of factors.