Differences in wetland plant community establishment with additions of nitrate-N and invasive species (Phalaris arundinacea and Typha ×glauca)

Abstract

Restored prairie pothole wetlands in North America are often enriched by nitrate-N (NO3-N) that has been lost from surrounding agricultural systems. In addition, these wetlands are increasingly colonized by invasive taxa including Phalaris arundinacea L. and Typha ×glauca Godr. To explore the impacts of NO3-N enrichment, suppression by invasive species, and the interaction of these factors on restored communities, we grew native sedge meadow communities from seed in greenhouse mesocosms and subjected them to NO3-N and invasive species for 4 months. Typha ×glauca did not reduce overall native community biomass and actually enhanced Aster spp. biomass. Phalaris arundinacea suppressed growth of the native community to an equal relative extent across all NO3-N levels. The shoot biomass of the entire native community in untreated plots was similar to the P. arundinacea fraction of the treated plots. Phalaris arundinacea demonstrated greater plasticity in root-shoot allocation than the native community over the range of NO3-N inputs. Proportional allocation to root biomass was greater for P. arundinacea than for the native community at all but the highest NO3-N level. Both factors may be important in explaining dominance of P. arundinacea over the native community in a range of fertility conditions. Regardless of NO3-N inputs, the restoration of diverse native wetlands requires strict control of P. arundinacea during community establishment, as evidenced by the relatively rapid rate of suppression of native community biomass by P. arundinacea compared with T. ×glauca.Key words: restoration, agricultural impacts, prairie pothole, root/shoot ratio.

Long-term monitoring of an invasion process: the case of an isolated small wetland on a Mediterranean Island

“…From a floristic point of view, several studies report a loss of diversity during the invasion of a wetland ecosystem (Green & Galatowitsch 2001;Ehrenfeld 2003;Bowles & Jones 2006;Boers et al 2006). Our data do not show such a loss in diversity but this is due to the loss of species with conservation value (according to Habitat Directive -ECE, 93/43 and the Law on Biodiversity of the Tuscany Administration -LR 56/2000, Regione Toscana) and the arrivals of common species with no conservation value.…”

“…Invasions of Typha spp. generate dense stands with low plant diversity (Green & Galatowitsch 2001;Ehrenfeld 2003;Bowles & Jones 2006;Boers et al 2006) and present a significant threat to wetland biodiversity. Invasion by Typha could lead to the loss of native species and alter ecosystem functioning, particularly affecting nutrient cycling, hydrology, and fire regimes (Vitousek & Walker 1989;Brooks et al 2004;Callaway & Maron 2006;Boers et al 2006).…”

Nutrient Accumulation by Phragmites australis and Phalaris arundinacea Growing in Two Constructed Wetlands for Wastewater Treatment

“…Studies have shown that Phalaris responds positively to nutrient enrichment. The controlled experiments of Green and Galatowitsch (2001) and Maurer and Zedler (2002) showed that high nutrient treatments increased biomass of Phalaris and increased allocation to aboveground growth. Also Kätterer and Andrén (1999) reported that fertilization decreased the amount of biomass allocated belowground as compared to aboveground biomass.…”

Improvement of Perennial Forage Species as Feedstock for Bioenergy

“…It is best adapted to low-lying areas subject to short-term flooding. In North America, it is highly vilified as an opportunist that has taken advantage of sedimentation and nutrient loading in wetlands to colonize and form vast monocultures within these ecosystems (Green and Galatowitsch 2001;Maurer and Zedler 2002).…”