The influence of water table fluctuations on nutrient dynamics in the rhizosphere of common reed (Phragmites australis)

Lake Cerknisko jezero is an intermittent lake and thus it is an ecosystem with permanent water level fluctuations. The lake area is covered mainly by wetland vegetation, with a common reed (Phragmites australis) as the prevailing species. The present research evaluated the influence of water table fluctuations on nutrient dynamics in the root zone of the reed. The content of nutrients (nitrate, nitrite, ammonium, soluble phosphorus) was monitored in the pore water, using ground samplers. The vitality of roots was determined measuring terminal electron transport (ETS) activity of root tissue on the vertical profile of the root system. The content of organic matter ranged from 33% up to 48% on a soil depth profile of 1 m. During the year nutrients were present on the whole profile. Water table fluctuations influenced the form, concentration and availability of nutrients in pore water and the vitality of roots. The measurements of potential respiration of root tissue (ETS activity) revealed the highest vitality in the upper layer of the rhizosphere.