Different nutrient use strategies of expansive grasses Calamagrostis epigejos and Arrhenatherum elatius

Enhanced nitrogen (N) levels accelerate expansion of Calamagrostis epigejos and Arrhenatherum elatius, highly aggressive expanders displacing original dry acidophilous grassland vegetation in the Podyji National Park (Czech Republic). We compared the capability of Calamagrostis and Arrhenatherum under control and N enhanced treatments to (i) accumulate N and phosphorus (P) in plant tissues, (ii) remove N and P from above-ground biomass during senescence and (iii) release N and P from plant material during decomposition of fresh formed litter. In control treatment, significantly higher amounts of total biomass and fresh aboveground litter were observed in Calamagrostis than in Arrhenatherum. Contrariwise, nutrient concentrations were significantly higher (11.6-14.3 mg N g(-1) and 2.3 mg P g(-1)) in Arrhenatherum peak aboveground biomass than in Calamagrostis (8.4-10.3 mg N g(-1) and 1.6-1.7 mg P g(-1)). Substantial differences between species were found in resorption of nutrients, mainly P, at the ends of growing seasons. While P concentrations in Arrhenatherum fresh litter were twice and three times higher (1.6-2.5 mg P g(-1)) than in Calamagrostis (0.7-0.8 mg P g(-1)), N concentrations were nearly doubled in Arrhenatherum (13.1-15.6 mg N g(-1)) in comparison with Calamagrostis (7.4-8.7 mg N g(-1)). Thus, the nutrients (N and mainly P) were retranslocated from the aboveground biomass of Calamagrostis probably more effectively in comparison with Arrhenatherum at the end of the growing season. On the other hand, Arrhenatherum litter was decomposed faster and consequently nutrient release (mainly N and P) was higher in comparison with Calamagrostis which pointed to different growth and nutrient use strategies of studied grass species.